Backends: DirectX10: Expose selected render state in ImGui_ImplDX10_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks. (#6969, #5834, #7468, #3590)

Amend e94f95d

backends/imgui_impl_dx10.cpp

@@ -15,6 +15,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2025-01-06: DirectX10: Expose selected render state in ImGui_ImplDX10_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
 //  2024-10-07: DirectX10: Changed default texture sampler to Clamp instead of Repeat/Wrap.
 //  2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11.
 //  2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX).
@@ -95,7 +96,28 @@ static void ImGui_ImplDX10_SetupRenderState(ImDrawData* draw_data, ID3D10Device*
     vp.TopLeftX = vp.TopLeftY = 0;
     device->RSSetViewports(1, &vp);
 
-    // Bind shader and vertex buffers
+    // Setup orthographic projection matrix into our constant buffer
+    // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
+    void* mapped_resource;
+    if (bd->pVertexConstantBuffer->Map(D3D10_MAP_WRITE_DISCARD, 0, &mapped_resource) == S_OK)
+    {
+        VERTEX_CONSTANT_BUFFER_DX10* constant_buffer = (VERTEX_CONSTANT_BUFFER_DX10*)mapped_resource;
+        float L = draw_data->DisplayPos.x;
+        float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
+        float T = draw_data->DisplayPos.y;
+        float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
+        float mvp[4][4] =
+        {
+            { 2.0f/(R-L),   0.0f,           0.0f,       0.0f },
+            { 0.0f,         2.0f/(T-B),     0.0f,       0.0f },
+            { 0.0f,         0.0f,           0.5f,       0.0f },
+            { (R+L)/(L-R),  (T+B)/(B-T),    0.5f,       1.0f },
+        };
+        memcpy(&constant_buffer->mvp, mvp, sizeof(mvp));
+        bd->pVertexConstantBuffer->Unmap();
+    }
+
+    // Setup shader and vertex buffers
     unsigned int stride = sizeof(ImDrawVert);
     unsigned int offset = 0;
     device->IASetInputLayout(bd->pInputLayout);
@@ -171,28 +193,6 @@ void ImGui_ImplDX10_RenderDrawData(ImDrawData* draw_data)
     bd->pVB->Unmap();
     bd->pIB->Unmap();
 
-    // Setup orthographic projection matrix into our constant buffer
-    // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
-    {
-        void* mapped_resource;
-        if (bd->pVertexConstantBuffer->Map(D3D10_MAP_WRITE_DISCARD, 0, &mapped_resource) != S_OK)
-            return;
-        VERTEX_CONSTANT_BUFFER_DX10* constant_buffer = (VERTEX_CONSTANT_BUFFER_DX10*)mapped_resource;
-        float L = draw_data->DisplayPos.x;
-        float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
-        float T = draw_data->DisplayPos.y;
-        float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
-        float mvp[4][4] =
-        {
-            { 2.0f/(R-L),   0.0f,           0.0f,       0.0f },
-            { 0.0f,         2.0f/(T-B),     0.0f,       0.0f },
-            { 0.0f,         0.0f,           0.5f,       0.0f },
-            { (R+L)/(L-R),  (T+B)/(B-T),    0.5f,       1.0f },
-        };
-        memcpy(&constant_buffer->mvp, mvp, sizeof(mvp));
-        bd->pVertexConstantBuffer->Unmap();
-    }
-
     // Backup DX state that will be modified to restore it afterwards (unfortunately this is very ugly looking and verbose. Close your eyes!)
     struct BACKUP_DX10_STATE
     {
@@ -236,6 +236,13 @@ void ImGui_ImplDX10_RenderDrawData(ImDrawData* draw_data)
 
     // Setup desired DX state
     ImGui_ImplDX10_SetupRenderState(draw_data, device);
+    // Setup render state structure (for callbacks and custom texture bindings)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    ImGui_ImplDX10_RenderState render_state;
+    render_state.Device = bd->pd3dDevice;
+    render_state.SamplerDefault = bd->pFontSampler;
+    render_state.VertexConstantBuffer = bd->pVertexConstantBuffer;
+    platform_io.Renderer_RenderState = &render_state;
 
     // Render command lists
     // (Because we merged all buffers into a single one, we maintain our own offset into them)
@@ -248,7 +255,7 @@ void ImGui_ImplDX10_RenderDrawData(ImDrawData* draw_data)
         for (int cmd_i = 0; cmd_i < draw_list->CmdBuffer.Size; cmd_i++)
         {
             const ImDrawCmd* pcmd = &draw_list->CmdBuffer[cmd_i];
-            if (pcmd->UserCallback)
+            if (pcmd->UserCallback != nullptr)
             {
                 // User callback, registered via ImDrawList::AddCallback()
                 // (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to reset render state.)
@@ -278,6 +285,7 @@ void ImGui_ImplDX10_RenderDrawData(ImDrawData* draw_data)
         global_idx_offset += draw_list->IdxBuffer.Size;
         global_vtx_offset += draw_list->VtxBuffer.Size;
     }
+    platform_io.Renderer_RenderState = nullptr;
 
     // Restore modified DX state
     device->RSSetScissorRects(old.ScissorRectsCount, old.ScissorRects);

backends/imgui_impl_dx10.h

@@ -18,6 +18,8 @@
 #ifndef IMGUI_DISABLE
 
 struct ID3D10Device;
+struct ID3D10SamplerState;
+struct ID3D10Buffer;
 
 // Follow "Getting Started" link and check examples/ folder to learn about using backends!
 IMGUI_IMPL_API bool     ImGui_ImplDX10_Init(ID3D10Device* device);
@@ -29,4 +31,14 @@ IMGUI_IMPL_API void     ImGui_ImplDX10_RenderDrawData(ImDrawData* draw_data);
 IMGUI_IMPL_API bool     ImGui_ImplDX10_CreateDeviceObjects();
 IMGUI_IMPL_API void     ImGui_ImplDX10_InvalidateDeviceObjects();
 
+// [BETA] Selected render state data shared with callbacks.
+// This is temporarily stored in GetPlatformIO().Renderer_RenderState during the ImGui_ImplDX10_RenderDrawData() call.
+// (Please open an issue if you feel you need access to more data)
+struct ImGui_ImplDX10_RenderState
+{
+    ID3D10Device*           Device;
+    ID3D10SamplerState*     SamplerDefault;
+    ID3D10Buffer*           VertexConstantBuffer;
+};
+
 #endif // #ifndef IMGUI_DISABLE

backends/imgui_impl_dx11.cpp

@@ -136,7 +136,7 @@ static void ImGui_ImplDX11_SetupRenderState(ImDrawData* draw_data, ID3D11DeviceC
     device_ctx->DSSetShader(nullptr, nullptr, 0); // In theory we should backup and restore this as well.. very infrequently used..
     device_ctx->CSSetShader(nullptr, nullptr, 0); // In theory we should backup and restore this as well.. very infrequently used..
 
-    // Setup blend state
+    // Setup render state
     const float blend_factor[4] = { 0.f, 0.f, 0.f, 0.f };
     device_ctx->OMSetBlendState(bd->pBlendState, blend_factor, 0xffffffff);
     device_ctx->OMSetDepthStencilState(bd->pDepthStencilState, 0);

docs/CHANGELOG.txt

@@ -74,6 +74,7 @@ Other changes:
   primarily for the purpose of making our examples simpler.
 - Backends: DX11: Expose vertex constant buffer in ImGui_ImplDX11_RenderState.
   Reset projection matrix in ImDrawCallback_ResetRenderState handlers. (#6969, #5834, #7468, #3590)
+- Backends: DX10: Expose ImGui_ImplDX10_RenderState for completeness. (#6969, #5834, #7468, #3590)
 - Examples: Added Win32+Vulkan example for completeness. (#8180) [@jristic]