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Fix basic example

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Context: When parsing a mesh with primitives that have indices pointing to different buffer views, the VAO will use the last GL_ELEMENT_ARRAY_BUFFER that was bound to it. In this scenario, the mesh will not be rendered properly.

When binding a mesh, return VAO and EBOs so that primitives can bind to the proper element array buffer.
This commit is contained in:
Emmanuel Arias Soto 2022-05-14 19:51:34 +02:00
parent 912856823d
commit a894904f11
1 changed files with 32 additions and 19 deletions
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51
examples/basic/main.cpp
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@ -39,8 +39,8 @@ bool loadModel(tinygltf::Model &model, const char *filename) {
return res;
}
std::map<int, GLuint> bindMesh(std::map<int, GLuint> vbos,
tinygltf::Model &model, tinygltf::Mesh &mesh) {
void bindMesh(std::map<int, GLuint>& vbos,
tinygltf::Model &model, tinygltf::Mesh &mesh) {
for (size_t i = 0; i < model.bufferViews.size(); ++i) {
const tinygltf::BufferView &bufferView = model.bufferViews[i];
if (bufferView.target == 0) { // TODO impl drawarrays
@ -144,12 +144,10 @@ std::map<int, GLuint> bindMesh(std::map<int, GLuint> vbos,
}
}
}
return vbos;
}
// bind models
void bindModelNodes(std::map<int, GLuint> vbos, tinygltf::Model &model,
void bindModelNodes(std::map<int, GLuint>& vbos, tinygltf::Model &model,
tinygltf::Node &node) {
if ((node.mesh >= 0) && (node.mesh < model.meshes.size())) {
bindMesh(vbos, model, model.meshes[node.mesh]);
@ -160,7 +158,8 @@ void bindModelNodes(std::map<int, GLuint> vbos, tinygltf::Model &model,
bindModelNodes(vbos, model, model.nodes[node.children[i]]);
}
}
GLuint bindModel(tinygltf::Model &model) {
std::pair<GLuint, std::map<int, GLuint>> bindModel(tinygltf::Model &model) {
std::map<int, GLuint> vbos;
GLuint vao;
glGenVertexArrays(1, &vao);
@ -173,19 +172,29 @@ GLuint bindModel(tinygltf::Model &model) {
}
glBindVertexArray(0);
// cleanup vbos
for (size_t i = 0; i < vbos.size(); ++i) {
glDeleteBuffers(1, &vbos[i]);
// cleanup vbos but do not delete index buffers yet
for (auto it = vbos.cbegin(); it != vbos.cend();) {
tinygltf::BufferView bufferView = model.bufferViews[it->first];
if (bufferView.target != GL_ELEMENT_ARRAY_BUFFER) {
glDeleteBuffers(1, &vbos[it->first]);
vbos.erase(it++);
}
else {
++it;
}
}
return vao;
return {vao, vbos};
}
void drawMesh(tinygltf::Model &model, tinygltf::Mesh &mesh) {
void drawMesh(const std::map<int, GLuint>& vbos,
tinygltf::Model &model, tinygltf::Mesh &mesh) {
for (size_t i = 0; i < mesh.primitives.size(); ++i) {
tinygltf::Primitive primitive = mesh.primitives[i];
tinygltf::Accessor indexAccessor = model.accessors[primitive.indices];
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vbos.at(indexAccessor.bufferView));
glDrawElements(primitive.mode, indexAccessor.count,
indexAccessor.componentType,
BUFFER_OFFSET(indexAccessor.byteOffset));
@ -193,20 +202,22 @@ void drawMesh(tinygltf::Model &model, tinygltf::Mesh &mesh) {
}
// recursively draw node and children nodes of model
void drawModelNodes(tinygltf::Model &model, tinygltf::Node &node) {
void drawModelNodes(const std::pair<GLuint, std::map<int, GLuint>>& vaoAndEbos,
tinygltf::Model &model, tinygltf::Node &node) {
if ((node.mesh >= 0) && (node.mesh < model.meshes.size())) {
drawMesh(model, model.meshes[node.mesh]);
drawMesh(vaoAndEbos.second, model, model.meshes[node.mesh]);
}
for (size_t i = 0; i < node.children.size(); i++) {
drawModelNodes(model, model.nodes[node.children[i]]);
drawModelNodes(vaoAndEbos, model, model.nodes[node.children[i]]);
}
}
void drawModel(GLuint vao, tinygltf::Model &model) {
glBindVertexArray(vao);
void drawModel(const std::pair<GLuint, std::map<int, GLuint>>& vaoAndEbos,
tinygltf::Model &model) {
glBindVertexArray(vaoAndEbos.first);
const tinygltf::Scene &scene = model.scenes[model.defaultScene];
for (size_t i = 0; i < scene.nodes.size(); ++i) {
drawModelNodes(model, model.nodes[scene.nodes[i]]);
drawModelNodes(vaoAndEbos, model, model.nodes[scene.nodes[i]]);
}
glBindVertexArray(0);
@ -282,7 +293,7 @@ void displayLoop(Window &window, const std::string &filename) {
tinygltf::Model model;
if (!loadModel(model, filename.c_str())) return;
GLuint vao = bindModel(model);
std::pair<GLuint, std::map<int, GLuint>> vaoAndEbos = bindModel(model);
// dbgModel(model); return;
// Model matrix : an identity matrix (model will be at the origin)
@ -317,10 +328,12 @@ void displayLoop(Window &window, const std::string &filename) {
glUniform3fv(sun_position_u, 1, &sun_position[0]);
glUniform3fv(sun_color_u, 1, &sun_color[0]);
drawModel(vao, model);
drawModel(vaoAndEbos, model);
glfwSwapBuffers(window.window);
glfwPollEvents();
}
glDeleteVertexArrays(1, &vaoAndEbos.first);
}
static void error_callback(int error, const char *description) {