Examples: Reworked setup of clear color to be compatible with transparent values. (#2693, #2764, #2766, #2873, #3447, #3813, #3816)

docs/CHANGELOG.txt

@@ -49,6 +49,7 @@ Other Changes:
   preserve alpha in output buffer (using SrcBlendAlpha = ONE, DstBlendAlpha = ONE_MINUS_SRC_ALPHA consistently
   accross all backends), facilitating compositing of the output buffer with another buffer.
   (#2693, #2764, #2766, #2873, #3447, #3813, #3816) [@ocornut, @thedmd, @ShawnM427, @Ubpa, @aiekick]
+- Examples: Reworked setup of clear color to be compatible with transparent values.
 - CI: Use a dedicated "scheduled" workflow to trigger scheduled builds. Forks may disable this workflow if
   scheduled builds builds are not required. [@rokups]
 

examples/example_allegro5/main.cpp

@@ -121,7 +121,7 @@ int main(int, char**)
 
         // Rendering
         ImGui::Render();
-        al_clear_to_color(al_map_rgba_f(clear_color.x, clear_color.y, clear_color.z, clear_color.w));
+        al_clear_to_color(al_map_rgba_f(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w));
         ImGui_ImplAllegro5_RenderDrawData(ImGui::GetDrawData());
         al_flip_display();
     }

examples/example_apple_metal/main.mm

@@ -245,7 +245,7 @@
     MTLRenderPassDescriptor* renderPassDescriptor = view.currentRenderPassDescriptor;
     if (renderPassDescriptor != nil)
     {
-        renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(clear_color[0], clear_color[1], clear_color[2], clear_color[3]);
+        renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(clear_color[0] * clear_color[3], clear_color[1] * clear_color[3], clear_color[2] * clear_color[3], clear_color[3]);
 
         // Here, you could do additional rendering work, including other passes as necessary.
 

examples/example_apple_opengl2/main.mm

@@ -97,7 +97,7 @@
     GLsizei height = (GLsizei)(draw_data->DisplaySize.y * draw_data->FramebufferScale.y);
     glViewport(0, 0, width, height);
 
-	glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+	glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
 	glClear(GL_COLOR_BUFFER_BIT);
 	ImGui_ImplOpenGL2_RenderDrawData(draw_data);
 

examples/example_emscripten_opengl3/main.cpp

@@ -167,7 +167,7 @@ static void main_loop(void* arg)
     ImGui::Render();
     SDL_GL_MakeCurrent(g_Window, g_GLContext);
     glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
-    glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
     glClear(GL_COLOR_BUFFER_BIT);
     ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
     SDL_GL_SwapWindow(g_Window);

examples/example_emscripten_wgpu/main.cpp

@@ -205,7 +205,7 @@ static void main_loop(void* window)
     WGPURenderPassColorAttachmentDescriptor color_attachments = {};
     color_attachments.loadOp = WGPULoadOp_Clear;
     color_attachments.storeOp = WGPUStoreOp_Store;
-    color_attachments.clearColor = { clear_color.x, clear_color.y, clear_color.z, clear_color.w };
+    color_attachments.clearColor = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
     color_attachments.attachment = wgpuSwapChainGetCurrentTextureView(wgpu_swap_chain);
     WGPURenderPassDescriptor render_pass_desc = {};
     render_pass_desc.colorAttachmentCount = 1;

examples/example_glfw_metal/main.mm

@@ -99,7 +99,7 @@ int main(int, char**)
             id<CAMetalDrawable> drawable = [layer nextDrawable];
 
             id<MTLCommandBuffer> commandBuffer = [commandQueue commandBuffer];
-            renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(clear_color[0], clear_color[1], clear_color[2], clear_color[3]);
+            renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(clear_color[0] * clear_color[3], clear_color[1] * clear_color[3], clear_color[2] * clear_color[3], clear_color[3]);
             renderPassDescriptor.colorAttachments[0].texture = drawable.texture;
             renderPassDescriptor.colorAttachments[0].loadAction = MTLLoadActionClear;
             renderPassDescriptor.colorAttachments[0].storeAction = MTLStoreActionStore;

examples/example_glfw_opengl2/main.cpp

@@ -132,7 +132,7 @@ int main(int, char**)
         int display_w, display_h;
         glfwGetFramebufferSize(window, &display_w, &display_h);
         glViewport(0, 0, display_w, display_h);
-        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+        glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
 
         // If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),

examples/example_glfw_opengl3/main.cpp

@@ -196,7 +196,7 @@ int main(int, char**)
         int display_w, display_h;
         glfwGetFramebufferSize(window, &display_w, &display_h);
         glViewport(0, 0, display_w, display_h);
-        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+        glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
 

examples/example_glfw_vulkan/main.cpp

@@ -520,7 +520,10 @@ int main(int, char**)
         const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
         if (!is_minimized)
         {
-            memcpy(&wd->ClearValue.color.float32[0], &clear_color, 4 * sizeof(float));
+            wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
+            wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
+            wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
+            wd->ClearValue.color.float32[3] = clear_color.w;
             FrameRender(wd, draw_data);
             FramePresent(wd);
         }

examples/example_glut_opengl2/main.cpp

@@ -76,7 +76,7 @@ void glut_display_func()
     ImGui::Render();
     ImGuiIO& io = ImGui::GetIO();
     glViewport(0, 0, (GLsizei)io.DisplaySize.x, (GLsizei)io.DisplaySize.y);
-    glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
     glClear(GL_COLOR_BUFFER_BIT);
     //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound, but prefer using the GL3+ code.
     ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());

examples/example_sdl_directx11/main.cpp

@@ -155,8 +155,9 @@ int main(int, char**)
 
         // Rendering
         ImGui::Render();
+        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
         g_pd3dDeviceContext->OMSetRenderTargets(1, &g_mainRenderTargetView, NULL);
-        g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, (float*)&clear_color);
+        g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
         ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
 
         g_pSwapChain->Present(1, 0); // Present with vsync

examples/example_sdl_metal/main.mm

@@ -107,7 +107,7 @@ int main(int, char**)
             id<CAMetalDrawable> drawable = [layer nextDrawable];
 
             id<MTLCommandBuffer> commandBuffer = [commandQueue commandBuffer];
-            renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(clear_color[0], clear_color[1], clear_color[2], clear_color[3]);
+            renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(clear_color[0] * clear_color[3], clear_color[1] * clear_color[3], clear_color[2] * clear_color[3], clear_color[3]);
             renderPassDescriptor.colorAttachments[0].texture = drawable.texture;
             renderPassDescriptor.colorAttachments[0].loadAction = MTLLoadActionClear;
             renderPassDescriptor.colorAttachments[0].storeAction = MTLStoreActionStore;

examples/example_sdl_opengl2/main.cpp

@@ -137,7 +137,7 @@ int main(int, char**)
         // Rendering
         ImGui::Render();
         glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
-        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+        glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
         //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound
         ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());

examples/example_sdl_opengl3/main.cpp

@@ -198,7 +198,7 @@ int main(int, char**)
         // Rendering
         ImGui::Render();
         glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
-        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+        glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
         SDL_GL_SwapWindow(window);

examples/example_sdl_vulkan/main.cpp

@@ -521,7 +521,10 @@ int main(int, char**)
         const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
         if (!is_minimized)
         {
-            memcpy(&wd->ClearValue.color.float32[0], &clear_color, 4 * sizeof(float));
+            wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
+            wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
+            wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
+            wd->ClearValue.color.float32[3] = clear_color.w;
             FrameRender(wd, draw_data);
             FramePresent(wd);
         }

examples/example_win32_directx10/main.cpp

@@ -140,8 +140,9 @@ int main(int, char**)
 
         // Rendering
         ImGui::Render();
+        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
         g_pd3dDevice->OMSetRenderTargets(1, &g_mainRenderTargetView, NULL);
-        g_pd3dDevice->ClearRenderTargetView(g_mainRenderTargetView, (float*)&clear_color);
+        g_pd3dDevice->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
         ImGui_ImplDX10_RenderDrawData(ImGui::GetDrawData());
 
         g_pSwapChain->Present(1, 0); // Present with vsync

examples/example_win32_directx11/main.cpp

@@ -140,8 +140,9 @@ int main(int, char**)
 
         // Rendering
         ImGui::Render();
+        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
         g_pd3dDeviceContext->OMSetRenderTargets(1, &g_mainRenderTargetView, NULL);
-        g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, (float*)&clear_color);
+        g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
         ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
 
         g_pSwapChain->Present(1, 0); // Present with vsync

examples/example_win32_directx12/main.cpp

@@ -193,7 +193,8 @@ int main(int, char**)
         g_pd3dCommandList->ResourceBarrier(1, &barrier);
 
         // Render Dear ImGui graphics
-        g_pd3dCommandList->ClearRenderTargetView(g_mainRenderTargetDescriptor[backBufferIdx], (float*)&clear_color, 0, NULL);
+        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
+        g_pd3dCommandList->ClearRenderTargetView(g_mainRenderTargetDescriptor[backBufferIdx], clear_color_with_alpha, 0, NULL);
         g_pd3dCommandList->OMSetRenderTargets(1, &g_mainRenderTargetDescriptor[backBufferIdx], FALSE, NULL);
         g_pd3dCommandList->SetDescriptorHeaps(1, &g_pd3dSrvDescHeap);
         ImGui_ImplDX12_RenderDrawData(ImGui::GetDrawData(), g_pd3dCommandList);
@@ -329,9 +330,11 @@ bool CreateDeviceD3D(HWND hWnd)
     {
         IDXGIFactory4* dxgiFactory = NULL;
         IDXGISwapChain1* swapChain1 = NULL;
-        if (CreateDXGIFactory1(IID_PPV_ARGS(&dxgiFactory)) != S_OK ||
-            dxgiFactory->CreateSwapChainForHwnd(g_pd3dCommandQueue, hWnd, &sd, NULL, NULL, &swapChain1) != S_OK ||
-            swapChain1->QueryInterface(IID_PPV_ARGS(&g_pSwapChain)) != S_OK)
+        if (CreateDXGIFactory1(IID_PPV_ARGS(&dxgiFactory)) != S_OK)
+            return false;
+        if (dxgiFactory->CreateSwapChainForHwnd(g_pd3dCommandQueue, hWnd, &sd, NULL, NULL, &swapChain1) != S_OK)
+            return false;
+        if (swapChain1->QueryInterface(IID_PPV_ARGS(&g_pSwapChain)) != S_OK)
             return false;
         swapChain1->Release();
         dxgiFactory->Release();

examples/example_win32_directx9/main.cpp

@@ -141,7 +141,7 @@ int main(int, char**)
         g_pd3dDevice->SetRenderState(D3DRS_ZENABLE, FALSE);
         g_pd3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE, FALSE);
         g_pd3dDevice->SetRenderState(D3DRS_SCISSORTESTENABLE, FALSE);
-        D3DCOLOR clear_col_dx = D3DCOLOR_RGBA((int)(clear_color.x*255.0f), (int)(clear_color.y*255.0f), (int)(clear_color.z*255.0f), (int)(clear_color.w*255.0f));
+        D3DCOLOR clear_col_dx = D3DCOLOR_RGBA((int)(clear_color.x*clear_color.w*255.0f), (int)(clear_color.y*clear_color.w*255.0f), (int)(clear_color.z*clear_color.w*255.0f), (int)(clear_color.w*255.0f));
         g_pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, clear_col_dx, 1.0f, 0);
         if (g_pd3dDevice->BeginScene() >= 0)
         {
@@ -178,7 +178,7 @@ bool CreateDeviceD3D(HWND hWnd)
     ZeroMemory(&g_d3dpp, sizeof(g_d3dpp));
     g_d3dpp.Windowed = TRUE;
     g_d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
-    g_d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;
+    g_d3dpp.BackBufferFormat = D3DFMT_UNKNOWN; // Need to use an explicit format with alpha if needing per-pixel alpha composition.
     g_d3dpp.EnableAutoDepthStencil = TRUE;
     g_d3dpp.AutoDepthStencilFormat = D3DFMT_D16;
     g_d3dpp.PresentationInterval = D3DPRESENT_INTERVAL_ONE;           // Present with vsync