Examples: OpenGL: Fix early return on zero-sized framebuffer breaking GL state (ocornut#486, ocornut#547)

Author: ocornut

examples/opengl3_example/imgui_impl_glfw_gl3.cpp

@@ -33,6 +33,14 @@ static unsigned int g_VboHandle = 0, g_VaoHandle = 0, g_ElementsHandle = 0;
 // - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
 void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawData* draw_data)
 {
+    // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
+    ImGuiIO& io = ImGui::GetIO();
+    int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x);
+    int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y);
+    if (fb_width == 0 || fb_height == 0)
+        return;
+    draw_data->ScaleClipRects(io.DisplayFramebufferScale);
+
     // Backup GL state
     GLint last_program; glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
     GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
@@ -58,14 +66,6 @@ void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawData* draw_data)
     glEnable(GL_SCISSOR_TEST);
     glActiveTexture(GL_TEXTURE0);
 
-    // Handle cases of screen coordinates != from framebuffer coordinates (e.g. retina displays)
-    ImGuiIO& io = ImGui::GetIO();
-    int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x);
-    int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y);
-    if (fb_width == 0 || fb_height == 0)
-        return;
-    draw_data->ScaleClipRects(io.DisplayFramebufferScale);
-
     // Setup viewport, orthographic projection matrix
     glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
     const float ortho_projection[4][4] =

examples/opengl_example/imgui_impl_glfw.cpp

@@ -28,6 +28,14 @@ static GLuint       g_FontTexture = 0;
 // - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
 void ImGui_ImplGlfw_RenderDrawLists(ImDrawData* draw_data)
 {
+    // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
+    ImGuiIO& io = ImGui::GetIO();
+    int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x);
+    int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y);
+    if (fb_width == 0 || fb_height == 0)
+        return;
+    draw_data->ScaleClipRects(io.DisplayFramebufferScale);
+
     // We are using the OpenGL fixed pipeline to make the example code simpler to read!
     // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers.
     GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
@@ -44,14 +52,6 @@ void ImGui_ImplGlfw_RenderDrawLists(ImDrawData* draw_data)
     glEnable(GL_TEXTURE_2D);
     //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context
 
-    // Handle cases of screen coordinates != from framebuffer coordinates (e.g. retina displays)
-    ImGuiIO& io = ImGui::GetIO();
-    int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x);
-    int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y);
-    if (fb_width == 0 || fb_height == 0)
-        return;
-    draw_data->ScaleClipRects(io.DisplayFramebufferScale);
-
     // Setup viewport, orthographic projection matrix
     glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
     glMatrixMode(GL_PROJECTION);

examples/sdl_opengl3_example/imgui_impl_sdl_gl3.cpp

@@ -28,6 +28,14 @@ static unsigned int g_VboHandle = 0, g_VaoHandle = 0, g_ElementsHandle = 0;
 // - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
 void ImGui_ImplSdlGL3_RenderDrawLists(ImDrawData* draw_data)
 {
+    // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
+    ImGuiIO& io = ImGui::GetIO();
+    int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x);
+    int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y);
+    if (fb_width == 0 || fb_height == 0)
+        return;
+    draw_data->ScaleClipRects(io.DisplayFramebufferScale);
+
     // Backup GL state
     GLint last_program; glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
     GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
@@ -53,14 +61,6 @@ void ImGui_ImplSdlGL3_RenderDrawLists(ImDrawData* draw_data)
     glEnable(GL_SCISSOR_TEST);
     glActiveTexture(GL_TEXTURE0);
 
-    // Handle cases of screen coordinates != from framebuffer coordinates (e.g. retina displays)
-    ImGuiIO& io = ImGui::GetIO();
-    int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x);
-    int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y);
-    if (fb_width == 0 || fb_height == 0)
-        return;
-    draw_data->ScaleClipRects(io.DisplayFramebufferScale);
-
     // Setup orthographic projection matrix
     glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
     const float ortho_projection[4][4] =

examples/sdl_opengl_example/imgui_impl_sdl.cpp

@@ -21,6 +21,14 @@ static GLuint       g_FontTexture = 0;
 // - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
 void ImGui_ImplSdl_RenderDrawLists(ImDrawData* draw_data)
 {
+    // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
+    ImGuiIO& io = ImGui::GetIO();
+    int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x);
+    int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y);
+    if (fb_width == 0 || fb_height == 0)
+        return;
+    draw_data->ScaleClipRects(io.DisplayFramebufferScale);
+
     // We are using the OpenGL fixed pipeline to make the example code simpler to read!
     // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers.
     GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
@@ -37,14 +45,6 @@ void ImGui_ImplSdl_RenderDrawLists(ImDrawData* draw_data)
     glEnable(GL_TEXTURE_2D);
     //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context
 
-    // Handle cases of screen coordinates != from framebuffer coordinates (e.g. retina displays)
-    ImGuiIO& io = ImGui::GetIO();
-    int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x);
-    int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y);
-    if (fb_width == 0 || fb_height == 0)
-        return;
-    draw_data->ScaleClipRects(io.DisplayFramebufferScale);
-
     // Setup viewport, orthographic projection matrix
     glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
     glMatrixMode(GL_PROJECTION);