Simplified texture flip and added comments

examples/shaders_custom_uniform.c

@@ -94,7 +94,7 @@ int main()
             
             SetCustomShader(shader);
             // NOTE: Render texture must be y-flipped due to default OpenGL coordinates (left-bottom)
-            DrawTextureRec(target.texture, (Rectangle){ 0, target.texture.height, target.texture.width, -target.texture.height }, (Vector2){ 0, 0 }, WHITE);
+            DrawTextureRec(target.texture, (Rectangle){ 0, 0, target.texture.width, -target.texture.height }, (Vector2){ 0, 0 }, WHITE);
             SetDefaultShader();
             
             DrawText("(c) Dwarf 3D model by David Moreno", screenWidth - 200, screenHeight - 20, 10, GRAY);

examples/shaders_postprocessing.c

@@ -82,7 +82,7 @@ int main()
             
             SetCustomShader(shader);
             // NOTE: Render texture must be y-flipped due to default OpenGL coordinates (left-bottom)
-            DrawTextureRec(target.texture, (Rectangle){ 0, target.texture.height, target.texture.width, -target.texture.height }, (Vector2){ 0, 0 }, WHITE);
+            DrawTextureRec(target.texture, (Rectangle){ 0, 0, target.texture.width, -target.texture.height }, (Vector2){ 0, 0 }, WHITE);
             SetDefaultShader();
             
             DrawText("(c) Dwarf 3D model by David Moreno", screenWidth - 200, screenHeight - 20, 10, DARKGRAY);

src/rlgl.c

@@ -1897,6 +1897,9 @@ Model rlglLoadModel(Mesh mesh)
 
     // Create buffers for our vertex data (positions, texcoords, normals)
     glGenBuffers(3, vertexBuffer);
+    
+    // NOTE: Default shader is assigned to model, so vbo buffers are properly linked to vertex attribs
+    // If model shader is changed, vbo buffers must be re-assigned to new location points (previously loaded)
 
     // Enable vertex attributes: position
     glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer[0]);
@@ -2489,13 +2492,14 @@ static Shader LoadDefaultShader(void)
 }
 
 // Get location handlers to for shader attributes and uniforms
+// NOTE: If any location is not found, loc point becomes -1
 static void LoadDefaultShaderLocations(Shader *shader)
 {
     // Get handles to GLSL input attibute locations
     shader->vertexLoc = glGetAttribLocation(shader->id, "vertexPosition");
     shader->texcoordLoc = glGetAttribLocation(shader->id, "vertexTexCoord");
     shader->normalLoc = glGetAttribLocation(shader->id, "vertexNormal");
-    shader->colorLoc = glGetAttribLocation(shader->id, "vertexColor");        // -1 if not found
+    shader->colorLoc = glGetAttribLocation(shader->id, "vertexColor");
 
     // Get handles to GLSL uniform locations (vertex shader)
     shader->mvpLoc  = glGetUniformLocation(shader->id, "mvpMatrix");
@@ -2503,8 +2507,8 @@ static void LoadDefaultShaderLocations(Shader *shader)
     // Get handles to GLSL uniform locations (fragment shader)
     shader->tintColorLoc = glGetUniformLocation(shader->id, "fragTintColor");
     shader->mapDiffuseLoc = glGetUniformLocation(shader->id, "texture0");
-    shader->mapNormalLoc = glGetUniformLocation(shader->id, "texture1");      // -1 if not found
-    shader->mapSpecularLoc = glGetUniformLocation(shader->id, "texture2");    // -1 if not found
+    shader->mapNormalLoc = glGetUniformLocation(shader->id, "texture1");
+    shader->mapSpecularLoc = glGetUniformLocation(shader->id, "texture2");
 }
 
 // Read text file

src/textures.c

@@ -1385,6 +1385,10 @@ void DrawTextureEx(Texture2D texture, Vector2 position, float rotation, float sc
 void DrawTextureRec(Texture2D texture, Rectangle sourceRec, Vector2 position, Color tint)
 {
     Rectangle destRec = { (int)position.x, (int)position.y, abs(sourceRec.width), abs(sourceRec.height) };
+    
+    if (sourceRec.width < 0) sourceRec.x -= sourceRec.width;
+    if (sourceRec.height < 0) sourceRec.y -= sourceRec.height;
+    
     Vector2 origin = { 0, 0 };
 
     DrawTexturePro(texture, sourceRec, destRec, origin, 0.0f, tint);