From 5f603c56dc6930c355a5b51389c7fcb05dea3777 Mon Sep 17 00:00:00 2001
From: Syoyo Fujita <syoyo@lighttransport.com>
Date: Mon, 6 Apr 2020 22:11:16 +0900
Subject: [PATCH] Do not segfault when the scene does not contain texture
 images. Fixes #251

---
 examples/basic/README.md |  4 +++
 examples/basic/main.cpp  | 76 +++++++++++++++++++++++-----------------
 2 files changed, 48 insertions(+), 32 deletions(-)

diff --git a/examples/basic/README.md b/examples/basic/README.md
index 67da089..dd68e0a 100644
--- a/examples/basic/README.md
+++ b/examples/basic/README.md
@@ -19,3 +19,7 @@ $ make
 Plese use solution file located at `basic` folder.
 
 
+## Limitation
+
+There are so many limitations in this example(e.g. no PBR shader. the shader only shows texture of textures[0] if available).
+
diff --git a/examples/basic/main.cpp b/examples/basic/main.cpp
index 1d196ae..e4e059e 100644
--- a/examples/basic/main.cpp
+++ b/examples/basic/main.cpp
@@ -100,42 +100,49 @@ std::map<int, GLuint> bindMesh(std::map<int, GLuint> vbos,
         std::cout << "vaa missing: " << attrib.first << std::endl;
     }
 
-    GLuint texid;
-    glGenTextures(1, &texid);
+    if (model.textures.size() > 0) {
+      // fixme: Use material's baseColor
+      tinygltf::Texture &tex = model.textures[0];
 
-    tinygltf::Texture &tex = model.textures[0];
-    tinygltf::Image &image = model.images[tex.source];
+      if (tex.source > -1) {
 
-    glBindTexture(GL_TEXTURE_2D, texid);
-    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
-    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+        GLuint texid;
+        glGenTextures(1, &texid);
 
-    GLenum format = GL_RGBA;
+        tinygltf::Image &image = model.images[tex.source];
 
-    if (image.component == 1) {
-      format = GL_RED;
-    } else if (image.component == 2) {
-      format = GL_RG;
-    } else if (image.component == 3) {
-      format = GL_RGB;
-    } else {
-      // ???
+        glBindTexture(GL_TEXTURE_2D, texid);
+        glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+
+        GLenum format = GL_RGBA;
+
+        if (image.component == 1) {
+          format = GL_RED;
+        } else if (image.component == 2) {
+          format = GL_RG;
+        } else if (image.component == 3) {
+          format = GL_RGB;
+        } else {
+          // ???
+        }
+
+        GLenum type = GL_UNSIGNED_BYTE;
+        if (image.bits == 8) {
+          // ok
+        } else if (image.bits == 16) {
+          type = GL_UNSIGNED_SHORT;
+        } else {
+          // ???
+        }
+
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image.width, image.height, 0,
+                     format, type, &image.image.at(0));
+      }
     }
-
-    GLenum type = GL_UNSIGNED_BYTE;
-    if (image.bits == 8) {
-      // ok
-    } else if (image.bits == 16) {
-      type = GL_UNSIGNED_SHORT;
-    } else {
-      // ???
-    }
-
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image.width, image.height, 0,
-                 format, type, &image.image.at(0));
   }
 
   return vbos;
@@ -144,8 +151,12 @@ std::map<int, GLuint> bindMesh(std::map<int, GLuint> vbos,
 // bind models
 void bindModelNodes(std::map<int, GLuint> vbos, tinygltf::Model &model,
                     tinygltf::Node &node) {
-  bindMesh(vbos, model, model.meshes[node.mesh]);
+  if ((node.mesh >= 0) && (node.mesh < model.meshes.size())) {
+    bindMesh(vbos, model, model.meshes[node.mesh]);
+  }
+
   for (size_t i = 0; i < node.children.size(); i++) {
+    assert((node.children[i] >= 0) && (node.children[i] < model.nodes.size()));
     bindModelNodes(vbos, model, model.nodes[node.children[i]]);
   }
 }
@@ -157,6 +168,7 @@ GLuint bindModel(tinygltf::Model &model) {
 
   const tinygltf::Scene &scene = model.scenes[model.defaultScene];
   for (size_t i = 0; i < scene.nodes.size(); ++i) {
+    assert((scene.nodes[i] >= 0) && (scene.nodes[i] < model.nodes.size()));
     bindModelNodes(vbos, model, model.nodes[scene.nodes[i]]);
   }