Examples: OpenGL2: Uploading font texture as RGBA32 to increase compatibility with users shaders for beginners (#824)

examples/opengl2_example/imgui_impl_glfw.cpp

@@ -161,7 +161,7 @@ bool ImGui_ImplGlfw_CreateDeviceObjects()
     ImGuiIO& io = ImGui::GetIO();
     unsigned char* pixels;
     int width, height;
-    io.Fonts->GetTexDataAsAlpha8(&pixels, &width, &height);
+    io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);   // Load as RGBA 32-bits (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory.
 
     // Upload texture to graphics system
     GLint last_texture;
@@ -170,7 +170,7 @@ bool ImGui_ImplGlfw_CreateDeviceObjects()
     glBindTexture(GL_TEXTURE_2D, g_FontTexture);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, width, height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, pixels);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
 
     // Store our identifier
     io.Fonts->TexID = (void *)(intptr_t)g_FontTexture;

examples/opengl3_example/imgui_impl_glfw_gl3.cpp

@@ -178,7 +178,7 @@ bool ImGui_ImplGlfwGL3_CreateFontsTexture()
     ImGuiIO& io = ImGui::GetIO();
     unsigned char* pixels;
     int width, height;
-    io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);   // Load as RGBA 32-bits for OpenGL3 demo because it is more likely to be compatible with user's existing shader.
+    io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);   // Load as RGBA 32-bits (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory.
 
     // Upload texture to graphics system
     GLint last_texture;