Backends: Rework blending equation to preserve alpha in output buffer accross all backends. (2693, 2764, 2766, 2873, 3447, 3813, 3816)
Some of the viewport ideas from 2766 are not in there yet (e.g. Vulkan: setting compositeAlpha based on cap.supportedCompositeAlpha)
diff --git a/backends/imgui_impl_allegro5.cpp b/backends/imgui_impl_allegro5.cpp
index db608e0..c4832b6 100644
--- a/backends/imgui_impl_allegro5.cpp
+++ b/backends/imgui_impl_allegro5.cpp
@@ -15,6 +15,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2021-02-18: Change blending equation to preserve alpha in output buffer.
// 2020-08-10: Inputs: Fixed horizontal mouse wheel direction.
// 2019-12-05: Inputs: Added support for ImGuiMouseCursor_NotAllowed mouse cursor.
// 2019-07-21: Inputs: Added mapping for ImGuiKey_KeyPadEnter.
@@ -68,7 +69,7 @@
static void ImGui_ImplAllegro5_SetupRenderState(ImDrawData* draw_data)
{
// Setup blending
- al_set_blender(ALLEGRO_ADD, ALLEGRO_ALPHA, ALLEGRO_INVERSE_ALPHA);
+ al_set_separate_blender(ALLEGRO_ADD, ALLEGRO_ALPHA, ALLEGRO_INVERSE_ALPHA, ALLEGRO_ADD, ALLEGRO_ONE, ALLEGRO_INVERSE_ALPHA);
// Setup orthographic projection matrix
// Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right).
diff --git a/backends/imgui_impl_dx10.cpp b/backends/imgui_impl_dx10.cpp
index 422f652..2884275 100644
--- a/backends/imgui_impl_dx10.cpp
+++ b/backends/imgui_impl_dx10.cpp
@@ -11,6 +11,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2021-02-18: DirectX10: Change blending equation to preserve alpha in output buffer.
// 2019-07-21: DirectX10: Backup, clear and restore Geometry Shader is any is bound when calling ImGui_ImplDX10_RenderDrawData().
// 2019-05-29: DirectX10: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
// 2019-04-30: DirectX10: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
@@ -439,8 +440,8 @@
desc.SrcBlend = D3D10_BLEND_SRC_ALPHA;
desc.DestBlend = D3D10_BLEND_INV_SRC_ALPHA;
desc.BlendOp = D3D10_BLEND_OP_ADD;
- desc.SrcBlendAlpha = D3D10_BLEND_INV_SRC_ALPHA;
- desc.DestBlendAlpha = D3D10_BLEND_ZERO;
+ desc.SrcBlendAlpha = D3D10_BLEND_ONE;
+ desc.DestBlendAlpha = D3D10_BLEND_INV_SRC_ALPHA;
desc.BlendOpAlpha = D3D10_BLEND_OP_ADD;
desc.RenderTargetWriteMask[0] = D3D10_COLOR_WRITE_ENABLE_ALL;
g_pd3dDevice->CreateBlendState(&desc, &g_pBlendState);
diff --git a/backends/imgui_impl_dx11.cpp b/backends/imgui_impl_dx11.cpp
index 3edfeae..f114cdc 100644
--- a/backends/imgui_impl_dx11.cpp
+++ b/backends/imgui_impl_dx11.cpp
@@ -11,6 +11,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2021-02-18: DirectX11: Change blending equation to preserve alpha in output buffer.
// 2019-08-01: DirectX11: Fixed code querying the Geometry Shader state (would generally error with Debug layer enabled).
// 2019-07-21: DirectX11: Backup, clear and restore Geometry Shader is any is bound when calling ImGui_ImplDX10_RenderDrawData. Clearing Hull/Domain/Compute shaders without backup/restore.
// 2019-05-29: DirectX11: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
@@ -451,8 +452,8 @@
desc.RenderTarget[0].SrcBlend = D3D11_BLEND_SRC_ALPHA;
desc.RenderTarget[0].DestBlend = D3D11_BLEND_INV_SRC_ALPHA;
desc.RenderTarget[0].BlendOp = D3D11_BLEND_OP_ADD;
- desc.RenderTarget[0].SrcBlendAlpha = D3D11_BLEND_INV_SRC_ALPHA;
- desc.RenderTarget[0].DestBlendAlpha = D3D11_BLEND_ZERO;
+ desc.RenderTarget[0].SrcBlendAlpha = D3D11_BLEND_ONE;
+ desc.RenderTarget[0].DestBlendAlpha = D3D11_BLEND_INV_SRC_ALPHA;
desc.RenderTarget[0].BlendOpAlpha = D3D11_BLEND_OP_ADD;
desc.RenderTarget[0].RenderTargetWriteMask = D3D11_COLOR_WRITE_ENABLE_ALL;
g_pd3dDevice->CreateBlendState(&desc, &g_pBlendState);
diff --git a/backends/imgui_impl_dx12.cpp b/backends/imgui_impl_dx12.cpp
index 39ca8f8..860fe66 100644
--- a/backends/imgui_impl_dx12.cpp
+++ b/backends/imgui_impl_dx12.cpp
@@ -15,6 +15,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2021-02-18: DirectX12: Change blending equation to preserve alpha in output buffer.
// 2021-01-11: DirectX12: Improve Windows 7 compatibility (for D3D12On7) by loading d3d12.dll dynamically.
// 2020-09-16: DirectX12: Avoid rendering calls with zero-sized scissor rectangle since it generates a validation layer warning.
// 2020-09-08: DirectX12: Clarified support for building on 32-bit systems by redefining ImTextureID.
@@ -585,8 +586,8 @@
desc.RenderTarget[0].SrcBlend = D3D12_BLEND_SRC_ALPHA;
desc.RenderTarget[0].DestBlend = D3D12_BLEND_INV_SRC_ALPHA;
desc.RenderTarget[0].BlendOp = D3D12_BLEND_OP_ADD;
- desc.RenderTarget[0].SrcBlendAlpha = D3D12_BLEND_INV_SRC_ALPHA;
- desc.RenderTarget[0].DestBlendAlpha = D3D12_BLEND_ZERO;
+ desc.RenderTarget[0].SrcBlendAlpha = D3D12_BLEND_ONE;
+ desc.RenderTarget[0].DestBlendAlpha = D3D12_BLEND_INV_SRC_ALPHA;
desc.RenderTarget[0].BlendOpAlpha = D3D12_BLEND_OP_ADD;
desc.RenderTarget[0].RenderTargetWriteMask = D3D12_COLOR_WRITE_ENABLE_ALL;
}
diff --git a/backends/imgui_impl_dx9.cpp b/backends/imgui_impl_dx9.cpp
index 2a575e8..44dea33 100644
--- a/backends/imgui_impl_dx9.cpp
+++ b/backends/imgui_impl_dx9.cpp
@@ -11,6 +11,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2021-02-18: DirectX9: Change blending equation to preserve alpha in output buffer.
// 2019-05-29: DirectX9: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
// 2019-04-30: DirectX9: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
// 2019-03-29: Misc: Fixed erroneous assert in ImGui_ImplDX9_InvalidateDeviceObjects().
@@ -67,6 +68,9 @@
g_pd3dDevice->SetRenderState(D3DRS_BLENDOP, D3DBLENDOP_ADD);
g_pd3dDevice->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA);
g_pd3dDevice->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA);
+ g_pd3dDevice->SetRenderState(D3DRS_SEPARATEALPHABLENDENABLE, TRUE);
+ g_pd3dDevice->SetRenderState(D3DRS_SRCBLENDALPHA, D3DBLEND_ONE);
+ g_pd3dDevice->SetRenderState(D3DRS_DESTBLENDALPHA, D3DBLEND_INVSRCALPHA);
g_pd3dDevice->SetRenderState(D3DRS_SCISSORTESTENABLE, TRUE);
g_pd3dDevice->SetRenderState(D3DRS_SHADEMODE, D3DSHADE_GOURAUD);
g_pd3dDevice->SetRenderState(D3DRS_FOGENABLE, FALSE);
diff --git a/backends/imgui_impl_metal.mm b/backends/imgui_impl_metal.mm
index b67c3ef..cb57c12 100644
--- a/backends/imgui_impl_metal.mm
+++ b/backends/imgui_impl_metal.mm
@@ -11,6 +11,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2021-02-18: Metal: Change blending equation to preserve alpha in output buffer.
// 2021-01-25: Metal: Fixed texture storage mode when building on Mac Catalyst.
// 2019-05-29: Metal: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
// 2019-04-30: Metal: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
@@ -386,10 +387,10 @@
pipelineDescriptor.colorAttachments[0].pixelFormat = self.framebufferDescriptor.colorPixelFormat;
pipelineDescriptor.colorAttachments[0].blendingEnabled = YES;
pipelineDescriptor.colorAttachments[0].rgbBlendOperation = MTLBlendOperationAdd;
- pipelineDescriptor.colorAttachments[0].alphaBlendOperation = MTLBlendOperationAdd;
pipelineDescriptor.colorAttachments[0].sourceRGBBlendFactor = MTLBlendFactorSourceAlpha;
- pipelineDescriptor.colorAttachments[0].sourceAlphaBlendFactor = MTLBlendFactorSourceAlpha;
pipelineDescriptor.colorAttachments[0].destinationRGBBlendFactor = MTLBlendFactorOneMinusSourceAlpha;
+ pipelineDescriptor.colorAttachments[0].alphaBlendOperation = MTLBlendOperationAdd;
+ pipelineDescriptor.colorAttachments[0].sourceAlphaBlendFactor = MTLBlendFactorOne;
pipelineDescriptor.colorAttachments[0].destinationAlphaBlendFactor = MTLBlendFactorOneMinusSourceAlpha;
pipelineDescriptor.depthAttachmentPixelFormat = self.framebufferDescriptor.depthPixelFormat;
pipelineDescriptor.stencilAttachmentPixelFormat = self.framebufferDescriptor.stencilPixelFormat;
diff --git a/backends/imgui_impl_opengl2.cpp b/backends/imgui_impl_opengl2.cpp
index 1419e2d..5771049 100644
--- a/backends/imgui_impl_opengl2.cpp
+++ b/backends/imgui_impl_opengl2.cpp
@@ -81,6 +81,7 @@
// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers, polygon fill.
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+ //glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA); // In order to composite our output buffer we need to preserve alpha
glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
glDisable(GL_STENCIL_TEST);
diff --git a/backends/imgui_impl_opengl3.cpp b/backends/imgui_impl_opengl3.cpp
index f3b2a93..b582851 100644
--- a/backends/imgui_impl_opengl3.cpp
+++ b/backends/imgui_impl_opengl3.cpp
@@ -13,6 +13,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2021-02-18: OpenGL: Change blending equation to preserve alpha in output buffer.
// 2021-01-03: OpenGL: Backup, setup and restore GL_STENCIL_TEST state.
// 2020-10-23: OpenGL: Backup, setup and restore GL_PRIMITIVE_RESTART state.
// 2020-10-15: OpenGL: Use glGetString(GL_VERSION) instead of glGetIntegerv(GL_MAJOR_VERSION, ...) when the later returns zero (e.g. Desktop GL 2.x)
@@ -247,7 +248,7 @@
// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, polygon fill
glEnable(GL_BLEND);
glBlendEquation(GL_FUNC_ADD);
- glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+ glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
glDisable(GL_STENCIL_TEST);
diff --git a/backends/imgui_impl_vulkan.cpp b/backends/imgui_impl_vulkan.cpp
index 44a555a..d8c00e9 100644
--- a/backends/imgui_impl_vulkan.cpp
+++ b/backends/imgui_impl_vulkan.cpp
@@ -22,6 +22,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2021-02-18: Vulkan: Change blending equation to preserve alpha in output buffer.
// 2021-01-27: Vulkan: Added support for custom function load and IMGUI_IMPL_VULKAN_NO_PROTOTYPES by using ImGui_ImplVulkan_LoadFunctions().
// 2020-11-11: Vulkan: Added support for specifying which subpass to reference during VkPipeline creation.
// 2020-09-07: Vulkan: Added VkPipeline parameter to ImGui_ImplVulkan_RenderDrawData (default to one passed to ImGui_ImplVulkan_Init).
@@ -815,8 +816,8 @@
color_attachment[0].srcColorBlendFactor = VK_BLEND_FACTOR_SRC_ALPHA;
color_attachment[0].dstColorBlendFactor = VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
color_attachment[0].colorBlendOp = VK_BLEND_OP_ADD;
- color_attachment[0].srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
- color_attachment[0].dstAlphaBlendFactor = VK_BLEND_FACTOR_ZERO;
+ color_attachment[0].srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE;
+ color_attachment[0].dstAlphaBlendFactor = VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
color_attachment[0].alphaBlendOp = VK_BLEND_OP_ADD;
color_attachment[0].colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
diff --git a/backends/imgui_impl_wgpu.cpp b/backends/imgui_impl_wgpu.cpp
index 089dbfd..1eb290a 100644
--- a/backends/imgui_impl_wgpu.cpp
+++ b/backends/imgui_impl_wgpu.cpp
@@ -12,6 +12,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2021-02-18: Change blending equation to preserve alpha in output buffer.
// 2021-01-28: Initial version.
#include "imgui.h"
@@ -638,7 +639,7 @@
{
color_state.format = g_renderTargetFormat;
color_state.alphaBlend.operation = WGPUBlendOperation_Add;
- color_state.alphaBlend.srcFactor = WGPUBlendFactor_SrcAlpha;
+ color_state.alphaBlend.srcFactor = WGPUBlendFactor_One;
color_state.alphaBlend.dstFactor = WGPUBlendFactor_OneMinusSrcAlpha;
color_state.colorBlend.operation = WGPUBlendOperation_Add;
color_state.colorBlend.srcFactor = WGPUBlendFactor_SrcAlpha;
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index c41e315..4a87a64 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -45,7 +45,11 @@
- ImDrawList: AddCircle, AddCircleFilled(): Tweaked default segment count calculation to honor MaxError
with more accuracy. Made default segment count always even for better looking result. (#3808) [@thedmd]
- ImDrawList: AddCircle, AddCircleFilled(): New default for style.
-- CI: Use a dedicated "scheduled" workflow to trigger scheduled builds. Forks may disable this workflow if
+- Backends: OpenGL, Vulkan, DX9, DX10, DX11, DX12, Metal, WebGPU, Allegro: Rework blending equation to
+ 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]
+- CI: Use a dedicated "scheduled" workflow to trigger scheduled builds. Forks may disable this workflow if
scheduled builds builds are not required. [@rokups]
