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Backends: DX9, DX10, DX11, DX12, Allegro5, OpenGL2, OpenGL3, SDLRenderer2, SDLRenderer3, SDLGPU3, Vulkan: added standard draw callbacks when possible. (#9378)

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This commit is contained in:
omar
2026-04-23 21:50:45 +02:00
committed by ocornut
parent 82f46a73f8
commit 0a811e8ea1
19 changed files with 244 additions and 45 deletions
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backends/imgui_impl_opengl2.cpp
+30 -3
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@@ -6,6 +6,7 @@
// [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
// Missing features or Issues:
// [ ] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
// [ ] Renderer: Use of DrawCallback_SetSamplerLinear, DrawCallback_SetSamplerNearest is emulated by poking to glTexParameter(), as legacy OpenGL doesn't have glBindSampler().
// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -25,6 +26,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2026-XX-XX: OpenGL: Added support for standard draw callbacks (in platform_io): DrawCallback_ResetRenderState, DrawCallback_SetSamplerLinear, DrawCallback_SetSamplerNearest.
// 2026-03-12: OpenGL: Fixed invalid assert in ImGui_ImplOpenGL3_UpdateTexture() if ImTextureID_Invalid is defined to be != 0, which became the default since 2026-03-12. (#9295)
// 2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
// 2025-07-15: OpenGL: Set GL_UNPACK_ALIGNMENT to 1 before updating textures. (#8802)
@@ -86,6 +88,9 @@
// OpenGL data
struct ImGui_ImplOpenGL2_Data
{
bool UseTexParameterToSetSampler;
GLuint NextSampler;
ImGui_ImplOpenGL2_Data() { memset((void*)this, 0, sizeof(*this)); }
};
@@ -107,6 +112,7 @@ void ImGui_ImplOpenGL2_NewFrame()
static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_width, int fb_height)
{
// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers, polygon fill.
ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData();
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
@@ -124,6 +130,7 @@ static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_wid
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glShadeModel(GL_SMOOTH);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
bd->NextSampler = GL_LINEAR;
// If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),
// you may need to backup/reset/restore other state, e.g. for current shader using the commented lines below.
@@ -148,12 +155,18 @@ static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_wid
glLoadIdentity();
}
// Draw callbacks
static void ImGui_ImplOpenGL2_DrawCallback_ResetRenderState(const ImDrawList*, const ImDrawCmd*) {} // Intentionally empty. Used as an identifier for rendering loop to call its code. Simpler to implement this way.
static void ImGui_ImplOpenGL2_DrawCallback_SetSamplerLinear(const ImDrawList*, const ImDrawCmd*) { ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); bd->UseTexParameterToSetSampler = true; bd->NextSampler = GL_LINEAR; }
static void ImGui_ImplOpenGL2_DrawCallback_SetSamplerNearest(const ImDrawList*, const ImDrawCmd*) { ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); bd->UseTexParameterToSetSampler = true; bd->NextSampler = GL_NEAREST; }
// OpenGL2 Render function.
// Note that this implementation is little overcomplicated because we are saving/setting up/restoring every OpenGL state explicitly.
// This is in order to be able to run within an OpenGL engine that doesn't do so.
void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
{
// Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData();
int fb_width = (int)(draw_data->DisplaySize.x * draw_data->FramebufferScale.x);
int fb_height = (int)(draw_data->DisplaySize.y * draw_data->FramebufferScale.y);
if (fb_width == 0 || fb_height == 0)
@@ -197,8 +210,7 @@ void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
if (pcmd->UserCallback)
{
// 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.)
if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
if (pcmd->UserCallback == ImGui_ImplOpenGL2_DrawCallback_ResetRenderState)
ImGui_ImplOpenGL2_SetupRenderState(draw_data, fb_width, fb_height);
else
pcmd->UserCallback(draw_list, pcmd);
@@ -215,7 +227,17 @@ void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
glScissor((int)clip_min.x, (int)((float)fb_height - clip_max.y), (int)(clip_max.x - clip_min.x), (int)(clip_max.y - clip_min.y));
// Bind texture, Draw
glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->GetTexID());
GLuint pcmd_texture = (GLuint)(intptr_t)pcmd->GetTexID();
glBindTexture(GL_TEXTURE_2D, pcmd_texture);
// Emulate sampler change (even though it is technically part of texture data)
// As a sort of hack/workaround, we only start writing using glTextParameter() if sampler is ever changed explicitly.
if (bd->UseTexParameterToSetSampler)
{
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, bd->NextSampler);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, bd->NextSampler);
}
glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer + pcmd->IdxOffset);
}
}
@@ -325,6 +347,11 @@ bool ImGui_ImplOpenGL2_Init()
io.BackendRendererName = "imgui_impl_opengl2";
io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures; // We can honor ImGuiPlatformIO::Textures[] requests during render.
ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
platform_io.DrawCallback_ResetRenderState = ImGui_ImplOpenGL2_DrawCallback_ResetRenderState;
platform_io.DrawCallback_SetSamplerLinear = ImGui_ImplOpenGL2_DrawCallback_SetSamplerLinear;
platform_io.DrawCallback_SetSamplerNearest = ImGui_ImplOpenGL2_DrawCallback_SetSamplerNearest;
return true;
}