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Initial skinning example(W.I.P).

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Syoyo Fujita 2018-09-22 17:51:05 +09:00
parent e66d8c992f
commit 0de4d7c05f
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examples/skinning/README.md Normal file
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# Simple glTF skinning sample with CPU skinning implementation.
Example use CPU implementation of skinning for the explanation of how to process skin property in glTF format.
OpenGL is used to display transformed vertex.
## Build on Linux and macOS
```
$ premake5 gmake
$ make
$ ./bin/native/Debug/skinning simple-skin.gltf
```
## Note on asset
`simple-skin.gltf` is grabbed from gltfTutorial https://github.com/KhronosGroup/glTF-Tutorials/blob/master/gltfTutorial/gltfTutorial_019_SimpleSkin.md

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examples/skinning/main.cc Normal file
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#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <limits>
#include <string>
#include <vector>
#include <GL/glew.h>
#define GLFW_INCLUDE_GLU
#include <GLFW/glfw3.h>
#include "trackball.h"
#define TINYGLTF_IMPLEMENTATION
#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "tiny_gltf.h"
//#define BUFFER_OFFSET(i) ((char *)NULL + (i))
#define BUFFER_OFFSET(i) (reinterpret_cast<void *>(i))
#define CheckGLErrors(desc) \
{ \
GLenum e = glGetError(); \
if (e != GL_NO_ERROR) { \
printf("OpenGL error in \"%s\": %d (%d) %s:%d\n", desc, e, e, __FILE__, \
__LINE__); \
exit(20); \
} \
}
#define CAM_Z (3.0f)
int width = 768;
int height = 768;
double prevMouseX, prevMouseY;
bool mouseLeftPressed;
bool mouseMiddlePressed;
bool mouseRightPressed;
float curr_quat[4];
float prev_quat[4];
float eye[3], lookat[3], up[3];
GLFWwindow *window;
typedef struct { GLuint vb; } GLBufferState;
typedef struct {
std::vector<GLuint> diffuseTex; // for each primitive in mesh
} GLMeshState;
typedef struct {
std::map<std::string, GLint> attribs;
std::map<std::string, GLint> uniforms;
} GLProgramState;
typedef struct {
GLuint vb; // vertex buffer
size_t count; // byte count
} GLCurvesState;
std::map<int, GLBufferState> gBufferState;
std::map<std::string, GLMeshState> gMeshState;
std::map<int, GLCurvesState> gCurvesMesh;
GLProgramState gGLProgramState;
void CheckErrors(std::string desc) {
GLenum e = glGetError();
if (e != GL_NO_ERROR) {
fprintf(stderr, "OpenGL error in \"%s\": %d (%d)\n", desc.c_str(), e, e);
exit(20);
}
}
static std::string GetFilePathExtension(const std::string &FileName) {
if (FileName.find_last_of(".") != std::string::npos)
return FileName.substr(FileName.find_last_of(".") + 1);
return "";
}
bool LoadShader(GLenum shaderType, // GL_VERTEX_SHADER or GL_FRAGMENT_SHADER(or
// maybe GL_COMPUTE_SHADER)
GLuint &shader, const char *shaderSourceFilename) {
GLint val = 0;
// free old shader/program
if (shader != 0) {
glDeleteShader(shader);
}
std::vector<GLchar> srcbuf;
FILE *fp = fopen(shaderSourceFilename, "rb");
if (!fp) {
fprintf(stderr, "failed to load shader: %s\n", shaderSourceFilename);
return false;
}
fseek(fp, 0, SEEK_END);
size_t len = ftell(fp);
rewind(fp);
srcbuf.resize(len + 1);
len = fread(&srcbuf.at(0), 1, len, fp);
srcbuf[len] = 0;
fclose(fp);
const GLchar *srcs[1];
srcs[0] = &srcbuf.at(0);
shader = glCreateShader(shaderType);
glShaderSource(shader, 1, srcs, NULL);
glCompileShader(shader);
glGetShaderiv(shader, GL_COMPILE_STATUS, &val);
if (val != GL_TRUE) {
char log[4096];
GLsizei msglen;
glGetShaderInfoLog(shader, 4096, &msglen, log);
printf("%s\n", log);
// assert(val == GL_TRUE && "failed to compile shader");
printf("ERR: Failed to load or compile shader [ %s ]\n",
shaderSourceFilename);
return false;
}
printf("Load shader [ %s ] OK\n", shaderSourceFilename);
return true;
}
bool LinkShader(GLuint &prog, GLuint &vertShader, GLuint &fragShader) {
GLint val = 0;
if (prog != 0) {
glDeleteProgram(prog);
}
prog = glCreateProgram();
glAttachShader(prog, vertShader);
glAttachShader(prog, fragShader);
glLinkProgram(prog);
glGetProgramiv(prog, GL_LINK_STATUS, &val);
assert(val == GL_TRUE && "failed to link shader");
printf("Link shader OK\n");
return true;
}
void reshapeFunc(GLFWwindow *window, int w, int h) {
(void)window;
int fb_w, fb_h;
glfwGetFramebufferSize(window, &fb_w, &fb_h);
glViewport(0, 0, fb_w, fb_h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0, (float)w / (float)h, 0.1f, 1000.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
width = w;
height = h;
}
void keyboardFunc(GLFWwindow *window, int key, int scancode, int action,
int mods) {
(void)scancode;
(void)mods;
if (action == GLFW_PRESS || action == GLFW_REPEAT) {
// Close window
if (key == GLFW_KEY_Q || key == GLFW_KEY_ESCAPE) {
glfwSetWindowShouldClose(window, GL_TRUE);
}
}
}
void clickFunc(GLFWwindow *window, int button, int action, int mods) {
double x, y;
glfwGetCursorPos(window, &x, &y);
bool shiftPressed = (mods & GLFW_MOD_SHIFT);
bool ctrlPressed = (mods & GLFW_MOD_CONTROL);
if ((button == GLFW_MOUSE_BUTTON_LEFT) && (!shiftPressed) && (!ctrlPressed)) {
mouseLeftPressed = true;
mouseMiddlePressed = false;
mouseRightPressed = false;
if (action == GLFW_PRESS) {
int id = -1;
// int id = ui.Proc(x, y);
if (id < 0) { // outside of UI
trackball(prev_quat, 0.0, 0.0, 0.0, 0.0);
}
} else if (action == GLFW_RELEASE) {
mouseLeftPressed = false;
}
}
if ((button == GLFW_MOUSE_BUTTON_RIGHT) ||
((button == GLFW_MOUSE_BUTTON_LEFT) && ctrlPressed)) {
if (action == GLFW_PRESS) {
mouseRightPressed = true;
mouseLeftPressed = false;
mouseMiddlePressed = false;
} else if (action == GLFW_RELEASE) {
mouseRightPressed = false;
}
}
if ((button == GLFW_MOUSE_BUTTON_MIDDLE) ||
((button == GLFW_MOUSE_BUTTON_LEFT) && shiftPressed)) {
if (action == GLFW_PRESS) {
mouseMiddlePressed = true;
mouseLeftPressed = false;
mouseRightPressed = false;
} else if (action == GLFW_RELEASE) {
mouseMiddlePressed = false;
}
}
}
void motionFunc(GLFWwindow *window, double mouse_x, double mouse_y) {
(void)window;
float rotScale = 1.0f;
float transScale = 2.0f;
if (mouseLeftPressed) {
trackball(prev_quat, rotScale * (2.0f * prevMouseX - width) / (float)width,
rotScale * (height - 2.0f * prevMouseY) / (float)height,
rotScale * (2.0f * mouse_x - width) / (float)width,
rotScale * (height - 2.0f * mouse_y) / (float)height);
add_quats(prev_quat, curr_quat, curr_quat);
} else if (mouseMiddlePressed) {
eye[0] += -transScale * (mouse_x - prevMouseX) / (float)width;
lookat[0] += -transScale * (mouse_x - prevMouseX) / (float)width;
eye[1] += transScale * (mouse_y - prevMouseY) / (float)height;
lookat[1] += transScale * (mouse_y - prevMouseY) / (float)height;
} else if (mouseRightPressed) {
eye[2] += transScale * (mouse_y - prevMouseY) / (float)height;
lookat[2] += transScale * (mouse_y - prevMouseY) / (float)height;
}
// Update mouse point
prevMouseX = mouse_x;
prevMouseY = mouse_y;
}
static void SetupMeshState(tinygltf::Model &model, GLuint progId) {
// Buffer
{
for (size_t i = 0; i < model.bufferViews.size(); i++) {
const tinygltf::BufferView &bufferView = model.bufferViews[i];
if (bufferView.target == 0) {
std::cout << "WARN: bufferView.target is zero" << std::endl;
continue; // Unsupported bufferView.
}
const tinygltf::Buffer &buffer = model.buffers[bufferView.buffer];
GLBufferState state;
glGenBuffers(1, &state.vb);
glBindBuffer(bufferView.target, state.vb);
std::cout << "buffer.size= " << buffer.data.size()
<< ", byteOffset = " << bufferView.byteOffset << std::endl;
glBufferData(bufferView.target, bufferView.byteLength,
&buffer.data.at(0) + bufferView.byteOffset, GL_STATIC_DRAW);
glBindBuffer(bufferView.target, 0);
gBufferState[i] = state;
}
}
#if 0 // TODO(syoyo): Implement
// Texture
{
for (size_t i = 0; i < model.meshes.size(); i++) {
const tinygltf::Mesh &mesh = model.meshes[i];
gMeshState[mesh.name].diffuseTex.resize(mesh.primitives.size());
for (size_t primId = 0; primId < mesh.primitives.size(); primId++) {
const tinygltf::Primitive &primitive = mesh.primitives[primId];
gMeshState[mesh.name].diffuseTex[primId] = 0;
if (primitive.material < 0) {
continue;
}
tinygltf::Material &mat = model.materials[primitive.material];
// printf("material.name = %s\n", mat.name.c_str());
if (mat.values.find("diffuse") != mat.values.end()) {
std::string diffuseTexName = mat.values["diffuse"].string_value;
if (model.textures.find(diffuseTexName) != model.textures.end()) {
tinygltf::Texture &tex = model.textures[diffuseTexName];
if (scene.images.find(tex.source) != model.images.end()) {
tinygltf::Image &image = model.images[tex.source];
GLuint texId;
glGenTextures(1, &texId);
glBindTexture(tex.target, texId);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexParameterf(tex.target, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameterf(tex.target, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// Ignore Texture.fomat.
GLenum format = GL_RGBA;
if (image.component == 3) {
format = GL_RGB;
}
glTexImage2D(tex.target, 0, tex.internalFormat, image.width,
image.height, 0, format, tex.type,
&image.image.at(0));
CheckErrors("texImage2D");
glBindTexture(tex.target, 0);
printf("TexId = %d\n", texId);
gMeshState[mesh.name].diffuseTex[primId] = texId;
}
}
}
}
}
}
#endif
glUseProgram(progId);
GLint vtloc = glGetAttribLocation(progId, "in_vertex");
GLint nrmloc = glGetAttribLocation(progId, "in_normal");
GLint uvloc = glGetAttribLocation(progId, "in_texcoord");
// GLint diffuseTexLoc = glGetUniformLocation(progId, "diffuseTex");
GLint isCurvesLoc = glGetUniformLocation(progId, "uIsCurves");
gGLProgramState.attribs["POSITION"] = vtloc;
gGLProgramState.attribs["NORMAL"] = nrmloc;
gGLProgramState.attribs["TEXCOORD_0"] = uvloc;
// gGLProgramState.uniforms["diffuseTex"] = diffuseTexLoc;
gGLProgramState.uniforms["isCurvesLoc"] = isCurvesLoc;
};
#if 0 // TODO(syoyo): Implement
// Setup curves geometry extension
static void SetupCurvesState(tinygltf::Scene &scene, GLuint progId) {
// Find curves primitive.
{
std::map<std::string, tinygltf::Mesh>::const_iterator it(
scene.meshes.begin());
std::map<std::string, tinygltf::Mesh>::const_iterator itEnd(
scene.meshes.end());
for (; it != itEnd; it++) {
const tinygltf::Mesh &mesh = it->second;
// Currently we only support one primitive per mesh.
if (mesh.primitives.size() > 1) {
continue;
}
for (size_t primId = 0; primId < mesh.primitives.size(); primId++) {
const tinygltf::Primitive &primitive = mesh.primitives[primId];
gMeshState[mesh.name].diffuseTex[primId] = 0;
if (primitive.material.empty()) {
continue;
}
bool has_curves = false;
if (primitive.extras.IsObject()) {
if (primitive.extras.Has("ext_mode")) {
const tinygltf::Value::Object &o =
primitive.extras.Get<tinygltf::Value::Object>();
const tinygltf::Value &ext_mode = o.find("ext_mode")->second;
if (ext_mode.IsString()) {
const std::string &str = ext_mode.Get<std::string>();
if (str.compare("curves") == 0) {
has_curves = true;
}
}
}
}
if (!has_curves) {
continue;
}
// Construct curves buffer
const tinygltf::Accessor &vtx_accessor =
scene.accessors[primitive.attributes.find("POSITION")->second];
const tinygltf::Accessor &nverts_accessor =
scene.accessors[primitive.attributes.find("NVERTS")->second];
const tinygltf::BufferView &vtx_bufferView =
scene.bufferViews[vtx_accessor.bufferView];
const tinygltf::BufferView &nverts_bufferView =
scene.bufferViews[nverts_accessor.bufferView];
const tinygltf::Buffer &vtx_buffer =
scene.buffers[vtx_bufferView.buffer];
const tinygltf::Buffer &nverts_buffer =
scene.buffers[nverts_bufferView.buffer];
// std::cout << "vtx_bufferView = " << vtx_accessor.bufferView <<
// std::endl;
// std::cout << "nverts_bufferView = " << nverts_accessor.bufferView <<
// std::endl;
// std::cout << "vtx_buffer.size = " << vtx_buffer.data.size() <<
// std::endl;
// std::cout << "nverts_buffer.size = " << nverts_buffer.data.size() <<
// std::endl;
const int *nverts =
reinterpret_cast<const int *>(nverts_buffer.data.data());
const float *vtx =
reinterpret_cast<const float *>(vtx_buffer.data.data());
// Convert to GL_LINES data.
std::vector<float> line_pts;
size_t vtx_offset = 0;
for (int k = 0; k < static_cast<int>(nverts_accessor.count); k++) {
for (int n = 0; n < nverts[k] - 1; n++) {
line_pts.push_back(vtx[3 * (vtx_offset + n) + 0]);
line_pts.push_back(vtx[3 * (vtx_offset + n) + 1]);
line_pts.push_back(vtx[3 * (vtx_offset + n) + 2]);
line_pts.push_back(vtx[3 * (vtx_offset + n + 1) + 0]);
line_pts.push_back(vtx[3 * (vtx_offset + n + 1) + 1]);
line_pts.push_back(vtx[3 * (vtx_offset + n + 1) + 2]);
// std::cout << "p0 " << vtx[3 * (vtx_offset + n) + 0] << ", "
// << vtx[3 * (vtx_offset + n) + 1] << ", "
// << vtx[3 * (vtx_offset + n) + 2] << std::endl;
// std::cout << "p1 " << vtx[3 * (vtx_offset + n+1) + 0] << ", "
// << vtx[3 * (vtx_offset + n+1) + 1] << ", "
// << vtx[3 * (vtx_offset + n+1) + 2] << std::endl;
}
vtx_offset += nverts[k];
}
GLCurvesState state;
glGenBuffers(1, &state.vb);
glBindBuffer(GL_ARRAY_BUFFER, state.vb);
glBufferData(GL_ARRAY_BUFFER, line_pts.size() * sizeof(float),
line_pts.data(), GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
state.count = line_pts.size() / 3;
gCurvesMesh[mesh.name] = state;
// Material
tinygltf::Material &mat = scene.materials[primitive.material];
// printf("material.name = %s\n", mat.name.c_str());
if (mat.values.find("diffuse") != mat.values.end()) {
std::string diffuseTexName = mat.values["diffuse"].string_value;
if (scene.textures.find(diffuseTexName) != scene.textures.end()) {
tinygltf::Texture &tex = scene.textures[diffuseTexName];
if (scene.images.find(tex.source) != scene.images.end()) {
tinygltf::Image &image = scene.images[tex.source];
GLuint texId;
glGenTextures(1, &texId);
glBindTexture(tex.target, texId);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexParameterf(tex.target, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameterf(tex.target, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// Ignore Texture.fomat.
GLenum format = GL_RGBA;
if (image.component == 3) {
format = GL_RGB;
}
glTexImage2D(tex.target, 0, tex.internalFormat, image.width,
image.height, 0, format, tex.type,
&image.image.at(0));
CheckErrors("texImage2D");
glBindTexture(tex.target, 0);
printf("TexId = %d\n", texId);
gMeshState[mesh.name].diffuseTex[primId] = texId;
}
}
}
}
}
}
glUseProgram(progId);
GLint vtloc = glGetAttribLocation(progId, "in_vertex");
GLint nrmloc = glGetAttribLocation(progId, "in_normal");
GLint uvloc = glGetAttribLocation(progId, "in_texcoord");
GLint diffuseTexLoc = glGetUniformLocation(progId, "diffuseTex");
GLint isCurvesLoc = glGetUniformLocation(progId, "uIsCurves");
gGLProgramState.attribs["POSITION"] = vtloc;
gGLProgramState.attribs["NORMAL"] = nrmloc;
gGLProgramState.attribs["TEXCOORD_0"] = uvloc;
gGLProgramState.uniforms["diffuseTex"] = diffuseTexLoc;
gGLProgramState.uniforms["uIsCurves"] = isCurvesLoc;
};
#endif
static void DrawMesh(tinygltf::Model &model, const tinygltf::Mesh &mesh) {
//// Skip curves primitive.
// if (gCurvesMesh.find(mesh.name) != gCurvesMesh.end()) {
// return;
//}
// if (gGLProgramState.uniforms["diffuseTex"] >= 0) {
// glUniform1i(gGLProgramState.uniforms["diffuseTex"], 0); // TEXTURE0
//}
if (gGLProgramState.uniforms["isCurvesLoc"] >= 0) {
glUniform1i(gGLProgramState.uniforms["isCurvesLoc"], 0);
}
for (size_t i = 0; i < mesh.primitives.size(); i++) {
const tinygltf::Primitive &primitive = mesh.primitives[i];
if (primitive.indices < 0) return;
// Assume TEXTURE_2D target for the texture object.
// glBindTexture(GL_TEXTURE_2D, gMeshState[mesh.name].diffuseTex[i]);
std::map<std::string, int>::const_iterator it(primitive.attributes.begin());
std::map<std::string, int>::const_iterator itEnd(
primitive.attributes.end());
for (; it != itEnd; it++) {
assert(it->second >= 0);
const tinygltf::Accessor &accessor = model.accessors[it->second];
glBindBuffer(GL_ARRAY_BUFFER, gBufferState[accessor.bufferView].vb);
CheckErrors("bind buffer");
int size = 1;
if (accessor.type == TINYGLTF_TYPE_SCALAR) {
size = 1;
} else if (accessor.type == TINYGLTF_TYPE_VEC2) {
size = 2;
} else if (accessor.type == TINYGLTF_TYPE_VEC3) {
size = 3;
} else if (accessor.type == TINYGLTF_TYPE_VEC4) {
size = 4;
} else {
assert(0);
}
// it->first would be "POSITION", "NORMAL", "TEXCOORD_0", ...
if ((it->first.compare("POSITION") == 0) ||
(it->first.compare("NORMAL") == 0) ||
(it->first.compare("TEXCOORD_0") == 0)) {
if (gGLProgramState.attribs[it->first] >= 0) {
// Compute byteStride from Accessor + BufferView combination.
int byteStride = accessor.ByteStride(model.bufferViews[accessor.bufferView]);
assert(byteStride != -1);
glVertexAttribPointer(gGLProgramState.attribs[it->first], size,
accessor.componentType, accessor.normalized ? GL_TRUE : GL_FALSE,
byteStride,
BUFFER_OFFSET(accessor.byteOffset));
CheckErrors("vertex attrib pointer");
glEnableVertexAttribArray(gGLProgramState.attribs[it->first]);
CheckErrors("enable vertex attrib array");
}
}
}
const tinygltf::Accessor &indexAccessor =
model.accessors[primitive.indices];
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,
gBufferState[indexAccessor.bufferView].vb);
CheckErrors("bind buffer");
int mode = -1;
if (primitive.mode == TINYGLTF_MODE_TRIANGLES) {
mode = GL_TRIANGLES;
} else if (primitive.mode == TINYGLTF_MODE_TRIANGLE_STRIP) {
mode = GL_TRIANGLE_STRIP;
} else if (primitive.mode == TINYGLTF_MODE_TRIANGLE_FAN) {
mode = GL_TRIANGLE_FAN;
} else if (primitive.mode == TINYGLTF_MODE_POINTS) {
mode = GL_POINTS;
} else if (primitive.mode == TINYGLTF_MODE_LINE) {
mode = GL_LINES;
} else if (primitive.mode == TINYGLTF_MODE_LINE_LOOP) {
mode = GL_LINE_LOOP;
} else {
assert(0);
}
glDrawElements(mode, indexAccessor.count, indexAccessor.componentType,
BUFFER_OFFSET(indexAccessor.byteOffset));
CheckErrors("draw elements");
{
std::map<std::string, int>::const_iterator it(
primitive.attributes.begin());
std::map<std::string, int>::const_iterator itEnd(
primitive.attributes.end());
for (; it != itEnd; it++) {
if ((it->first.compare("POSITION") == 0) ||
(it->first.compare("NORMAL") == 0) ||
(it->first.compare("TEXCOORD_0") == 0)) {
if (gGLProgramState.attribs[it->first] >= 0) {
glDisableVertexAttribArray(gGLProgramState.attribs[it->first]);
}
}
}
}
}
}
#if 0 // TODO(syoyo): Implement
static void DrawCurves(tinygltf::Scene &scene, const tinygltf::Mesh &mesh) {
(void)scene;
if (gCurvesMesh.find(mesh.name) == gCurvesMesh.end()) {
return;
}
if (gGLProgramState.uniforms["isCurvesLoc"] >= 0) {
glUniform1i(gGLProgramState.uniforms["isCurvesLoc"], 1);
}
GLCurvesState &state = gCurvesMesh[mesh.name];
if (gGLProgramState.attribs["POSITION"] >= 0) {
glBindBuffer(GL_ARRAY_BUFFER, state.vb);
glVertexAttribPointer(gGLProgramState.attribs["POSITION"], 3, GL_FLOAT,
GL_FALSE, /* stride */ 0, BUFFER_OFFSET(0));
CheckErrors("curve: vertex attrib pointer");
glEnableVertexAttribArray(gGLProgramState.attribs["POSITION"]);
CheckErrors("curve: enable vertex attrib array");
}
glDrawArrays(GL_LINES, 0, state.count);
if (gGLProgramState.attribs["POSITION"] >= 0) {
glDisableVertexAttribArray(gGLProgramState.attribs["POSITION"]);
}
}
#endif
// Hierarchically draw nodes
static void DrawNode(tinygltf::Model &model, const tinygltf::Node &node) {
// Apply xform
glPushMatrix();
if (node.matrix.size() == 16) {
// Use `matrix' attribute
glMultMatrixd(node.matrix.data());
} else {
// Assume Trans x Rotate x Scale order
if (node.scale.size() == 3) {
glScaled(node.scale[0], node.scale[1], node.scale[2]);
}
if (node.rotation.size() == 4) {
glRotated(node.rotation[0], node.rotation[1], node.rotation[2],
node.rotation[3]);
}
if (node.translation.size() == 3) {
glTranslated(node.translation[0], node.translation[1],
node.translation[2]);
}
}
// std::cout << "node " << node.name << ", Meshes " << node.meshes.size() <<
// std::endl;
// std::cout << it->first << std::endl;
// FIXME(syoyo): Refactor.
// DrawCurves(scene, it->second);
DrawMesh(model, model.meshes[node.mesh]);
// Draw child nodes.
for (size_t i = 0; i < node.children.size(); i++) {
DrawNode(model, model.nodes[node.children[i]]);
}
glPopMatrix();
}
static void DrawModel(tinygltf::Model &model, int scene_idx) {
#if 0
std::map<std::string, tinygltf::Mesh>::const_iterator it(scene.meshes.begin());
std::map<std::string, tinygltf::Mesh>::const_iterator itEnd(scene.meshes.end());
for (; it != itEnd; it++) {
DrawMesh(scene, it->second);
DrawCurves(scene, it->second);
}
#else
const tinygltf::Scene &scene = model.scenes[scene_idx];
for (size_t i = 0; i < scene.nodes.size(); i++) {
DrawNode(model, model.nodes[scene.nodes[i]]);
}
#endif
}
static void Init() {
trackball(curr_quat, 0, 0, 0, 0);
eye[0] = 0.0f;
eye[1] = 0.0f;
eye[2] = CAM_Z;
lookat[0] = 0.0f;
lookat[1] = 0.0f;
lookat[2] = 0.0f;
up[0] = 0.0f;
up[1] = 1.0f;
up[2] = 0.0f;
}
static void PrintNodes(const tinygltf::Scene &scene) {
for (size_t i = 0; i < scene.nodes.size(); i++) {
std::cout << "node.name : " << scene.nodes[i] << std::endl;
}
}
int main(int argc, char **argv) {
if (argc < 2) {
std::cout << "glview input.gltf <scale>\n" << std::endl;
return 0;
}
float scale = 1.0f;
if (argc > 2) {
scale = atof(argv[2]);
}
tinygltf::Model model;
tinygltf::TinyGLTF loader;
std::string err;
std::string warn;
std::string input_filename(argv[1]);
std::string ext = GetFilePathExtension(input_filename);
bool ret = false;
if (ext.compare("glb") == 0) {
// assume binary glTF.
ret = loader.LoadBinaryFromFile(&model, &err, &warn, input_filename.c_str());
} else {
// assume ascii glTF.
ret = loader.LoadASCIIFromFile(&model, &err, &warn, input_filename.c_str());
}
if (!warn.empty()) {
printf("Warn: %s\n", warn.c_str());
}
if (!err.empty()) {
printf("ERR: %s\n", err.c_str());
}
if (!ret) {
printf("Failed to load .glTF : %s\n", argv[1]);
exit(-1);
}
Init();
if (model.scenes.empty()) {
std::cerr << "Scene is empty" << std::endl;
return EXIT_FAILURE;
}
std::cout << "defaultScene = " << model.defaultScene << std::endl;
if (model.defaultScene >= int(model.scenes.size())) {
std::cerr << "Invalid defualtScene value : " << model.defaultScene << std::endl;
return EXIT_FAILURE;
}
int scene_idx = model.defaultScene;
if (scene_idx == -1) {
// Use the first scene.
scene_idx = 0;
}
// DBG
PrintNodes(model.scenes[scene_idx]);
if (!glfwInit()) {
std::cerr << "Failed to initialize GLFW." << std::endl;
return -1;
}
char title[1024];
sprintf(title, "Simple glTF viewer: %s", input_filename.c_str());
window = glfwCreateWindow(width, height, title, NULL, NULL);
if (window == NULL) {
std::cerr << "Failed to open GLFW window. " << std::endl;
glfwTerminate();
return 1;
}
glfwGetWindowSize(window, &width, &height);
glfwMakeContextCurrent(window);
// Callback
glfwSetWindowSizeCallback(window, reshapeFunc);
glfwSetKeyCallback(window, keyboardFunc);
glfwSetMouseButtonCallback(window, clickFunc);
glfwSetCursorPosCallback(window, motionFunc);
glewExperimental = true; // This may be only true for linux environment.
if (glewInit() != GLEW_OK) {
std::cerr << "Failed to initialize GLEW." << std::endl;
return -1;
}
reshapeFunc(window, width, height);
GLuint vertId = 0, fragId = 0, progId = 0;
if (false == LoadShader(GL_VERTEX_SHADER, vertId, "shader.vert")) {
return -1;
}
CheckErrors("load vert shader");
if (false == LoadShader(GL_FRAGMENT_SHADER, fragId, "shader.frag")) {
return -1;
}
CheckErrors("load frag shader");
if (false == LinkShader(progId, vertId, fragId)) {
return -1;
}
CheckErrors("link");
{
// At least `in_vertex` should be used in the shader.
GLint vtxLoc = glGetAttribLocation(progId, "in_vertex");
if (vtxLoc < 0) {
printf("vertex loc not found.\n");
exit(-1);
}
}
glUseProgram(progId);
CheckErrors("useProgram");
SetupMeshState(model, progId);
// SetupCurvesState(model, progId);
CheckErrors("SetupGLState");
std::cout << "# of meshes = " << model.meshes.size() << std::endl;
while (glfwWindowShouldClose(window) == GL_FALSE) {
glfwPollEvents();
glClearColor(0.1f, 0.2f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
GLfloat mat[4][4];
build_rotmatrix(mat, curr_quat);
// camera(define it in projection matrix)
glMatrixMode(GL_PROJECTION);
glPushMatrix();
gluLookAt(eye[0], eye[1], eye[2], lookat[0], lookat[1], lookat[2], up[0],
up[1], up[2]);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glMultMatrixf(&mat[0][0]);
glScalef(scale, scale, scale);
DrawModel(model, scene_idx);
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glFlush();
glfwSwapBuffers(window);
}
glfwTerminate();
}

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examples/skinning/premake5.lua Normal file
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newoption {
trigger = "asan",
description = "Enable Address Sanitizer(gcc5+ ang clang only)"
}
solution "skinning"
-- location ( "build" )
configurations { "Debug", "Release" }
platforms {"native", "x64", "x32"}
project "skinning"
-- Use clang for better asan expericen
if _OPTIONS["asan"] then
toolset "clang"
end
kind "ConsoleApp"
language "C++"
cppdialect "C++11"
files { "main.cc", "skinning.cc", "trackball.cc" }
includedirs { "./" }
includedirs { "../../" }
configuration { "linux" }
if _OPTIONS["asan"] then
buildoptions { "-fsanitize=address" }
linkoptions { "-fsanitize=address" }
end
linkoptions { "`pkg-config --libs glfw3`" }
links { "GL", "GLU", "m", "GLEW", "X11", "Xrandr", "Xinerama", "Xi", "Xxf86vm", "Xcursor", "dl" }
configuration { "windows" }
-- Edit path to glew and GLFW3 fit to your environment.
includedirs { "../../../../local/glew-1.13.0/include/" }
includedirs { "../../../../local/glfw-3.2.bin.WIN32/include/" }
libdirs { "../../../../local/glew-1.13.0/lib/Release/Win32/" }
libdirs { "../../../../local/glfw-3.2.bin.WIN32/lib-vc2013/" }
links { "glfw3", "gdi32", "winmm", "user32", "glew32", "glu32","opengl32", "kernel32" }
defines { "_CRT_SECURE_NO_WARNINGS" }
configuration { "macosx" }
includedirs { "/usr/local/include" }
buildoptions { "-Wno-deprecated-declarations" }
libdirs { "/usr/local/lib" }
links { "glfw3", "GLEW" }
linkoptions { "-framework OpenGL", "-framework Cocoa", "-framework IOKit", "-framework CoreVideo" }
configuration "Debug"
defines { "DEBUG" }
symbols "On"
warnings "Extra"
configuration "Release"
defines { "NDEBUG" }
optimize "On"
warnings "Extra"

16
examples/skinning/shader.frag Normal file
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uniform sampler2D diffuseTex;
uniform int uIsCurve;
varying vec3 normal;
varying vec2 texcoord;
void main(void)
{
//gl_FragColor = vec4(0.5 * normalize(normal) + 0.5, 1.0);
//gl_FragColor = vec4(texcoord, 0.0, 1.0);
if (uIsCurve > 0) {
gl_FragColor = texture2D(diffuseTex, texcoord);
} else {
gl_FragColor = vec4(0.5 * normalize(normal) + 0.5, 1.0);
}
}

16
examples/skinning/shader.vert Normal file
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attribute vec3 in_vertex;
attribute vec3 in_normal;
attribute vec2 in_texcoord;
varying vec3 normal;
varying vec2 texcoord;
void main(void)
{
vec4 p = gl_ModelViewProjectionMatrix * vec4(in_vertex, 1);
gl_Position = p;
vec4 nn = gl_ModelViewMatrixInverseTranspose * vec4(normalize(in_normal), 0);
normal = nn.xyz;
texcoord = in_texcoord;
}

148
examples/skinning/simple-skin.gltf Normal file
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{
"scenes" : [ {
"nodes" : [ 0 ]
} ],
"nodes" : [ {
"skin" : 0,
"mesh" : 0,
"children" : [ 1 ]
}, {
"children" : [ 2 ],
"translation" : [ 0.0, 1.0, 0.0 ]
}, {
"rotation" : [ 0.0, 0.0, 0.0, 1.0 ]
} ],
"meshes" : [ {
"primitives" : [ {
"attributes" : {
"POSITION" : 1,
"JOINTS_0" : 2,
"WEIGHTS_0" : 3
},
"indices" : 0
} ]
} ],
"skins" : [ {
"inverseBindMatrices" : 4,
"joints" : [ 1, 2 ]
} ],
"animations" : [ {
"channels" : [ {
"sampler" : 0,
"target" : {
"node" : 2,
"path" : "rotation"
}
} ],
"samplers" : [ {
"input" : 5,
"interpolation" : "LINEAR",
"output" : 6
} ]
} ],
"buffers" : [ {
"uri" : "data:application/gltf-buffer;base64,AAABAAMAAAADAAIAAgADAAUAAgAFAAQABAAFAAcABAAHAAYABgAHAAkABgAJAAgAAAAAAAAAAAAAAAAAAACAPwAAAAAAAAAAAAAAAAAAAD8AAAAAAACAPwAAAD8AAAAAAAAAAAAAgD8AAAAAAACAPwAAgD8AAAAAAAAAAAAAwD8AAAAAAACAPwAAwD8AAAAAAAAAAAAAAEAAAAAAAACAPwAAAEAAAAAA",
"byteLength" : 168
}, {
"uri" : "data:application/gltf-buffer;base64,AAABAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAgD8AAAAAAAAAAAAAAAAAAIA/AAAAAAAAAAAAAAAAAABAPwAAgD4AAAAAAAAAAAAAQD8AAIA+AAAAAAAAAAAAAAA/AAAAPwAAAAAAAAAAAAAAPwAAAD8AAAAAAAAAAAAAgD4AAEA/AAAAAAAAAAAAAIA+AABAPwAAAAAAAAAAAAAAAAAAgD8AAAAAAAAAAAAAAAAAAIA/AAAAAAAAAAA=",
"byteLength" : 320
}, {
"uri" : "data:application/gltf-buffer;base64,AACAPwAAAAAAAAAAAAAAAAAAAAAAAIA/AAAAAAAAAAAAAAAAAAAAAAAAgD8AAAAAAAAAvwAAgL8AAAAAAACAPwAAgD8AAAAAAAAAAAAAAAAAAAAAAACAPwAAAAAAAAAAAAAAAAAAAAAAAIA/AAAAAAAAAL8AAIC/AAAAAAAAgD8=",
"byteLength" : 128
}, {
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"byteLength" : 240
} ],
"bufferViews" : [ {
"buffer" : 0,
"byteOffset" : 0,
"byteLength" : 48,
"target" : 34963
}, {
"buffer" : 0,
"byteOffset" : 48,
"byteLength" : 120,
"target" : 34962
}, {
"buffer" : 1,
"byteOffset" : 0,
"byteLength" : 320,
"byteStride" : 16
}, {
"buffer" : 2,
"byteOffset" : 0,
"byteLength" : 128
}, {
"buffer" : 3,
"byteOffset" : 0,
"byteLength" : 240
} ],
"accessors" : [ {
"bufferView" : 0,
"byteOffset" : 0,
"componentType" : 5123,
"count" : 24,
"type" : "SCALAR",
"max" : [ 9 ],
"min" : [ 0 ]
}, {
"bufferView" : 1,
"byteOffset" : 0,
"componentType" : 5126,
"count" : 10,
"type" : "VEC3",
"max" : [ 1.0, 2.0, 0.0 ],
"min" : [ 0.0, 0.0, 0.0 ]
}, {
"bufferView" : 2,
"byteOffset" : 0,
"componentType" : 5123,
"count" : 10,
"type" : "VEC4",
"max" : [ 0, 1, 0, 0 ],
"min" : [ 0, 1, 0, 0 ]
}, {
"bufferView" : 2,
"byteOffset" : 160,
"componentType" : 5126,
"count" : 10,
"type" : "VEC4",
"max" : [ 1.0, 1.0, 0.0, 0.0 ],
"min" : [ 0.0, 0.0, 0.0, 0.0 ]
}, {
"bufferView" : 3,
"byteOffset" : 0,
"componentType" : 5126,
"count" : 2,
"type" : "MAT4",
"max" : [ 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, -0.5, -1.0, 0.0, 1.0 ],
"min" : [ 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, -0.5, -1.0, 0.0, 1.0 ]
}, {
"bufferView" : 4,
"byteOffset" : 0,
"componentType" : 5126,
"count" : 12,
"type" : "SCALAR",
"max" : [ 5.5 ],
"min" : [ 0.0 ]
}, {
"bufferView" : 4,
"byteOffset" : 48,
"componentType" : 5126,
"count" : 12,
"type" : "VEC4",
"max" : [ 0.0, 0.0, 0.707, 1.0 ],
"min" : [ 0.0, 0.0, -0.707, 0.707 ]
} ],
"asset" : {
"version" : "2.0"
}
}

9
examples/skinning/skinning.cc Normal file
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#if 0
jointMatrix(j) =
globalTransform^-1 * // The "^-1" here means the inverse of this transform
globalJointTransform *
inverseBindMatrix(j);
#endif

292
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/*
* (c) Copyright 1993, 1994, Silicon Graphics, Inc.
* ALL RIGHTS RESERVED
* Permission to use, copy, modify, and distribute this software for
* any purpose and without fee is hereby granted, provided that the above
* copyright notice appear in all copies and that both the copyright notice
* and this permission notice appear in supporting documentation, and that
* the name of Silicon Graphics, Inc. not be used in advertising
* or publicity pertaining to distribution of the software without specific,
* written prior permission.
*
* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
* AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
* KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
* LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
* THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
* ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
* POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
*
* US Government Users Restricted Rights
* Use, duplication, or disclosure by the Government is subject to
* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
* (c)(1)(ii) of the Rights in Technical Data and Computer Software
* clause at DFARS 252.227-7013 and/or in similar or successor
* clauses in the FAR or the DOD or NASA FAR Supplement.
* Unpublished-- rights reserved under the copyright laws of the
* United States. Contractor/manufacturer is Silicon Graphics,
* Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
*
* OpenGL(TM) is a trademark of Silicon Graphics, Inc.
*/
/*
* Trackball code:
*
* Implementation of a virtual trackball.
* Implemented by Gavin Bell, lots of ideas from Thant Tessman and
* the August '88 issue of Siggraph's "Computer Graphics," pp. 121-129.
*
* Vector manip code:
*
* Original code from:
* David M. Ciemiewicz, Mark Grossman, Henry Moreton, and Paul Haeberli
*
* Much mucking with by:
* Gavin Bell
*/
#include <math.h>
#include "trackball.h"
/*
* This size should really be based on the distance from the center of
* rotation to the point on the object underneath the mouse. That
* point would then track the mouse as closely as possible. This is a
* simple example, though, so that is left as an Exercise for the
* Programmer.
*/
#define TRACKBALLSIZE (0.8)
/*
* Local function prototypes (not defined in trackball.h)
*/
static float tb_project_to_sphere(float, float, float);
static void normalize_quat(float[4]);
static void vzero(float *v) {
v[0] = 0.0;
v[1] = 0.0;
v[2] = 0.0;
}
static void vset(float *v, float x, float y, float z) {
v[0] = x;
v[1] = y;
v[2] = z;
}
static void vsub(const float *src1, const float *src2, float *dst) {
dst[0] = src1[0] - src2[0];
dst[1] = src1[1] - src2[1];
dst[2] = src1[2] - src2[2];
}
static void vcopy(const float *v1, float *v2) {
register int i;
for (i = 0; i < 3; i++)
v2[i] = v1[i];
}
static void vcross(const float *v1, const float *v2, float *cross) {
float temp[3];
temp[0] = (v1[1] * v2[2]) - (v1[2] * v2[1]);
temp[1] = (v1[2] * v2[0]) - (v1[0] * v2[2]);
temp[2] = (v1[0] * v2[1]) - (v1[1] * v2[0]);
vcopy(temp, cross);
}
static float vlength(const float *v) {
return sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
}
static void vscale(float *v, float div) {
v[0] *= div;
v[1] *= div;
v[2] *= div;
}
static void vnormal(float *v) { vscale(v, 1.0 / vlength(v)); }
static float vdot(const float *v1, const float *v2) {
return v1[0] * v2[0] + v1[1] * v2[1] + v1[2] * v2[2];
}
static void vadd(const float *src1, const float *src2, float *dst) {
dst[0] = src1[0] + src2[0];
dst[1] = src1[1] + src2[1];
dst[2] = src1[2] + src2[2];
}
/*
* Ok, simulate a track-ball. Project the points onto the virtual
* trackball, then figure out the axis of rotation, which is the cross
* product of P1 P2 and O P1 (O is the center of the ball, 0,0,0)
* Note: This is a deformed trackball-- is a trackball in the center,
* but is deformed into a hyperbolic sheet of rotation away from the
* center. This particular function was chosen after trying out
* several variations.
*
* It is assumed that the arguments to this routine are in the range
* (-1.0 ... 1.0)
*/
void trackball(float q[4], float p1x, float p1y, float p2x, float p2y) {
float a[3]; /* Axis of rotation */
float phi; /* how much to rotate about axis */
float p1[3], p2[3], d[3];
float t;
if (p1x == p2x && p1y == p2y) {
/* Zero rotation */
vzero(q);
q[3] = 1.0;
return;
}
/*
* First, figure out z-coordinates for projection of P1 and P2 to
* deformed sphere
*/
vset(p1, p1x, p1y, tb_project_to_sphere(TRACKBALLSIZE, p1x, p1y));
vset(p2, p2x, p2y, tb_project_to_sphere(TRACKBALLSIZE, p2x, p2y));
/*
* Now, we want the cross product of P1 and P2
*/
vcross(p2, p1, a);
/*
* Figure out how much to rotate around that axis.
*/
vsub(p1, p2, d);
t = vlength(d) / (2.0 * TRACKBALLSIZE);
/*
* Avoid problems with out-of-control values...
*/
if (t > 1.0)
t = 1.0;
if (t < -1.0)
t = -1.0;
phi = 2.0 * asin(t);
axis_to_quat(a, phi, q);
}
/*
* Given an axis and angle, compute quaternion.
*/
void axis_to_quat(float a[3], float phi, float q[4]) {
vnormal(a);
vcopy(a, q);
vscale(q, sin(phi / 2.0));
q[3] = cos(phi / 2.0);
}
/*
* Project an x,y pair onto a sphere of radius r OR a hyperbolic sheet
* if we are away from the center of the sphere.
*/
static float tb_project_to_sphere(float r, float x, float y) {
float d, t, z;
d = sqrt(x * x + y * y);
if (d < r * 0.70710678118654752440) { /* Inside sphere */
z = sqrt(r * r - d * d);
} else { /* On hyperbola */
t = r / 1.41421356237309504880;
z = t * t / d;
}
return z;
}
/*
* Given two rotations, e1 and e2, expressed as quaternion rotations,
* figure out the equivalent single rotation and stuff it into dest.
*
* This routine also normalizes the result every RENORMCOUNT times it is
* called, to keep error from creeping in.
*
* NOTE: This routine is written so that q1 or q2 may be the same
* as dest (or each other).
*/
#define RENORMCOUNT 97
void add_quats(float q1[4], float q2[4], float dest[4]) {
static int count = 0;
float t1[4], t2[4], t3[4];
float tf[4];
vcopy(q1, t1);
vscale(t1, q2[3]);
vcopy(q2, t2);
vscale(t2, q1[3]);
vcross(q2, q1, t3);
vadd(t1, t2, tf);
vadd(t3, tf, tf);
tf[3] = q1[3] * q2[3] - vdot(q1, q2);
dest[0] = tf[0];
dest[1] = tf[1];
dest[2] = tf[2];
dest[3] = tf[3];
if (++count > RENORMCOUNT) {
count = 0;
normalize_quat(dest);
}
}
/*
* Quaternions always obey: a^2 + b^2 + c^2 + d^2 = 1.0
* If they don't add up to 1.0, dividing by their magnitued will
* renormalize them.
*
* Note: See the following for more information on quaternions:
*
* - Shoemake, K., Animating rotation with quaternion curves, Computer
* Graphics 19, No 3 (Proc. SIGGRAPH'85), 245-254, 1985.
* - Pletinckx, D., Quaternion calculus as a basic tool in computer
* graphics, The Visual Computer 5, 2-13, 1989.
*/
static void normalize_quat(float q[4]) {
int i;
float mag;
mag = (q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3]);
for (i = 0; i < 4; i++)
q[i] /= mag;
}
/*
* Build a rotation matrix, given a quaternion rotation.
*
*/
void build_rotmatrix(float m[4][4], const float q[4]) {
m[0][0] = 1.0 - 2.0 * (q[1] * q[1] + q[2] * q[2]);
m[0][1] = 2.0 * (q[0] * q[1] - q[2] * q[3]);
m[0][2] = 2.0 * (q[2] * q[0] + q[1] * q[3]);
m[0][3] = 0.0;
m[1][0] = 2.0 * (q[0] * q[1] + q[2] * q[3]);
m[1][1] = 1.0 - 2.0 * (q[2] * q[2] + q[0] * q[0]);
m[1][2] = 2.0 * (q[1] * q[2] - q[0] * q[3]);
m[1][3] = 0.0;
m[2][0] = 2.0 * (q[2] * q[0] - q[1] * q[3]);
m[2][1] = 2.0 * (q[1] * q[2] + q[0] * q[3]);
m[2][2] = 1.0 - 2.0 * (q[1] * q[1] + q[0] * q[0]);
m[2][3] = 0.0;
m[3][0] = 0.0;
m[3][1] = 0.0;
m[3][2] = 0.0;
m[3][3] = 1.0;
}

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/*
* (c) Copyright 1993, 1994, Silicon Graphics, Inc.
* ALL RIGHTS RESERVED
* Permission to use, copy, modify, and distribute this software for
* any purpose and without fee is hereby granted, provided that the above
* copyright notice appear in all copies and that both the copyright notice
* and this permission notice appear in supporting documentation, and that
* the name of Silicon Graphics, Inc. not be used in advertising
* or publicity pertaining to distribution of the software without specific,
* written prior permission.
*
* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
* AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
* KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
* LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
* THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
* ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
* POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
*
* US Government Users Restricted Rights
* Use, duplication, or disclosure by the Government is subject to
* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
* (c)(1)(ii) of the Rights in Technical Data and Computer Software
* clause at DFARS 252.227-7013 and/or in similar or successor
* clauses in the FAR or the DOD or NASA FAR Supplement.
* Unpublished-- rights reserved under the copyright laws of the
* United States. Contractor/manufacturer is Silicon Graphics,
* Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
*
* OpenGL(TM) is a trademark of Silicon Graphics, Inc.
*/
/*
* trackball.h
* A virtual trackball implementation
* Written by Gavin Bell for Silicon Graphics, November 1988.
*/
/*
* Pass the x and y coordinates of the last and current positions of
* the mouse, scaled so they are from (-1.0 ... 1.0).
*
* The resulting rotation is returned as a quaternion rotation in the
* first paramater.
*/
void trackball(float q[4], float p1x, float p1y, float p2x, float p2y);
void negate_quat(float *q, float *qn);
/*
* Given two quaternions, add them together to get a third quaternion.
* Adding quaternions to get a compound rotation is analagous to adding
* translations to get a compound translation. When incrementally
* adding rotations, the first argument here should be the new
* rotation, the second and third the total rotation (which will be
* over-written with the resulting new total rotation).
*/
void add_quats(float *q1, float *q2, float *dest);
/*
* A useful function, builds a rotation matrix in Matrix based on
* given quaternion.
*/
void build_rotmatrix(float m[4][4], const float q[4]);
/*
* This function computes a quaternion based on an axis (defined by
* the given vector) and an angle about which to rotate. The angle is
* expressed in radians. The result is put into the third argument.
*/
void axis_to_quat(float a[3], float phi, float q[4]);