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Backends: DX11: Expose vertex constant buffer in ImGui_ImplDX11_RenderState.

DX9 and DX12 users can already alter the projection matrix (in undocumented ways, but possible)
This commit is contained in:
ocornut 2025-01-06 18:20:56 +01:00
parent 93a93071a2
commit af271e7330
3 changed files with 27 additions and 22 deletions

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@ -16,6 +16,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2025-01-06: DirectX11: Expose VertexConstantBuffer in ImGui_ImplDX11_RenderState. Reset projection matrix in ImDrawCallback_ResetRenderState handler.
// 2024-10-07: DirectX11: Changed default texture sampler to Clamp instead of Repeat/Wrap.
// 2024-10-07: DirectX11: Expose selected render state in ImGui_ImplDX11_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
// 2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11.
@ -98,6 +99,27 @@ static void ImGui_ImplDX11_SetupRenderState(ImDrawData* draw_data, ID3D11DeviceC
vp.TopLeftX = vp.TopLeftY = 0;
device_ctx->RSSetViewports(1, &vp);
// 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.
D3D11_MAPPED_SUBRESOURCE mapped_resource;
if (device_ctx->Map(bd->pVertexConstantBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mapped_resource) == S_OK)
{
VERTEX_CONSTANT_BUFFER_DX11* constant_buffer = (VERTEX_CONSTANT_BUFFER_DX11*)mapped_resource.pData;
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));
device_ctx->Unmap(bd->pVertexConstantBuffer, 0);
}
// Setup shader and vertex buffers
unsigned int stride = sizeof(ImDrawVert);
unsigned int offset = 0;
@ -179,28 +201,6 @@ void ImGui_ImplDX11_RenderDrawData(ImDrawData* draw_data)
device->Unmap(bd->pVB, 0);
device->Unmap(bd->pIB, 0);
// 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.
{
D3D11_MAPPED_SUBRESOURCE mapped_resource;
if (device->Map(bd->pVertexConstantBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mapped_resource) != S_OK)
return;
VERTEX_CONSTANT_BUFFER_DX11* constant_buffer = (VERTEX_CONSTANT_BUFFER_DX11*)mapped_resource.pData;
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));
device->Unmap(bd->pVertexConstantBuffer, 0);
}
// Backup DX state that will be modified to restore it afterwards (unfortunately this is very ugly looking and verbose. Close your eyes!)
struct BACKUP_DX11_STATE
{
@ -255,6 +255,7 @@ void ImGui_ImplDX11_RenderDrawData(ImDrawData* draw_data)
render_state.Device = bd->pd3dDevice;
render_state.DeviceContext = bd->pd3dDeviceContext;
render_state.SamplerDefault = bd->pFontSampler;
render_state.VertexConstantBuffer = bd->pVertexConstantBuffer;
platform_io.Renderer_RenderState = &render_state;
// Render command lists

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@ -21,6 +21,7 @@
struct ID3D11Device;
struct ID3D11DeviceContext;
struct ID3D11SamplerState;
struct ID3D11Buffer;
// Follow "Getting Started" link and check examples/ folder to learn about using backends!
IMGUI_IMPL_API bool ImGui_ImplDX11_Init(ID3D11Device* device, ID3D11DeviceContext* device_context);
@ -40,6 +41,7 @@ struct ImGui_ImplDX11_RenderState
ID3D11Device* Device;
ID3D11DeviceContext* DeviceContext;
ID3D11SamplerState* SamplerDefault;
ID3D11Buffer* VertexConstantBuffer;
};
#endif // #ifndef IMGUI_DISABLE

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@ -72,6 +72,8 @@ Other changes:
platforms not supporting VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR. (#8222) [@Zer0xFF]
- Backends: Vulkan: Added a few more ImGui_ImplVulkanH_XXX helper functions
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)
- Examples: Added Win32+Vulkan example for completeness. (#8180) [@jristic]