From 04bc0b0bb832233b568746cf03f419de81502846 Mon Sep 17 00:00:00 2001 From: ocornut Date: Wed, 5 Jan 2022 12:15:58 +0100 Subject: [PATCH] Fix IdxBuffer related comments. (#4845, #4863) --- imgui.cpp | 19 ++++++++++++------- imgui.h | 8 ++++---- 2 files changed, 16 insertions(+), 11 deletions(-) diff --git a/imgui.cpp b/imgui.cpp index 32fd8c7682a2..453e6a72e9c1 100644 --- a/imgui.cpp +++ b/imgui.cpp @@ -295,6 +295,7 @@ CODE // TODO: Setup viewport covering draw_data->DisplayPos to draw_data->DisplayPos + draw_data->DisplaySize // TODO: Setup orthographic projection matrix cover draw_data->DisplayPos to draw_data->DisplayPos + draw_data->DisplaySize // TODO: Setup shader: vertex { float2 pos, float2 uv, u32 color }, fragment shader sample color from 1 texture, multiply by vertex color. + ImVec2 clip_off = draw_data->DisplayPos; for (int n = 0; n < draw_data->CmdListsCount; n++) { const ImDrawList* cmd_list = draw_data->CmdLists[n]; @@ -309,9 +310,11 @@ CODE } else { - // The texture for the draw call is specified by pcmd->GetTexID(). - // The vast majority of draw calls will use the Dear ImGui texture atlas, which value you have set yourself during initialization. - MyEngineBindTexture((MyTexture*)pcmd->GetTexID()); + // Project scissor/clipping rectangles into framebuffer space + ImVec2 clip_min(pcmd->ClipRect.x - clip_off.x, pcmd->ClipRect.y - clip_off.y); + ImVec2 clip_max(pcmd->ClipRect.z - clip_off.x, pcmd->ClipRect.w - clip_off.y); + if (clip_max.x <= clip_min.x || clip_max.y <= clip_min.y) + continue; // We are using scissoring to clip some objects. All low-level graphics API should support it. // - If your engine doesn't support scissoring yet, you may ignore this at first. You will get some small glitches @@ -322,14 +325,16 @@ CODE // - In the interest of supporting multi-viewport applications (see 'docking' branch on github), // always subtract draw_data->DisplayPos from clipping bounds to convert them to your viewport space. // - Note that pcmd->ClipRect contains Min+Max bounds. Some graphics API may use Min+Max, other may use Min+Size (size being Max-Min) - ImVec2 pos = draw_data->DisplayPos; - MyEngineScissor((int)(pcmd->ClipRect.x - pos.x), (int)(pcmd->ClipRect.y - pos.y), (int)(pcmd->ClipRect.z - pos.x), (int)(pcmd->ClipRect.w - pos.y)); + MyEngineSetScissor(clip_min.x, clip_min.y, clip_max.x, clip_max.y); + + // The texture for the draw call is specified by pcmd->GetTexID(). + // The vast majority of draw calls will use the Dear ImGui texture atlas, which value you have set yourself during initialization. + MyEngineBindTexture((MyTexture*)pcmd->GetTexID()); // Render 'pcmd->ElemCount/3' indexed triangles. // By default the indices ImDrawIdx are 16-bit, you can change them to 32-bit in imconfig.h if your engine doesn't support 16-bit indices. - MyEngineDrawIndexedTriangles(pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer, vtx_buffer); + MyEngineDrawIndexedTriangles(pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer + pcmd->IdxOffset, vtx_buffer, pcmd->VtxOffset); } - idx_buffer += pcmd->ElemCount; } } } diff --git a/imgui.h b/imgui.h index d2edfa3634a1..552137c32c20 100644 --- a/imgui.h +++ b/imgui.h @@ -2278,16 +2278,16 @@ typedef void (*ImDrawCallback)(const ImDrawList* parent_list, const ImDrawCmd* c #define ImDrawCallback_ResetRenderState (ImDrawCallback)(-1) // Typically, 1 command = 1 GPU draw call (unless command is a callback) -// - VtxOffset/IdxOffset: When 'io.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset' is enabled, -// those fields allow us to render meshes larger than 64K vertices while keeping 16-bit indices. -// Pre-1.71 backends will typically ignore the VtxOffset/IdxOffset fields. +// - VtxOffset: When 'io.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset' is enabled, +// this fields allow us to render meshes larger than 64K vertices while keeping 16-bit indices. +// Backends made for <1.71. will typically ignore the VtxOffset fields. // - The ClipRect/TextureId/VtxOffset fields must be contiguous as we memcmp() them together (this is asserted for). struct ImDrawCmd { ImVec4 ClipRect; // 4*4 // Clipping rectangle (x1, y1, x2, y2). Subtract ImDrawData->DisplayPos to get clipping rectangle in "viewport" coordinates ImTextureID TextureId; // 4-8 // User-provided texture ID. Set by user in ImfontAtlas::SetTexID() for fonts or passed to Image*() functions. Ignore if never using images or multiple fonts atlas. unsigned int VtxOffset; // 4 // Start offset in vertex buffer. ImGuiBackendFlags_RendererHasVtxOffset: always 0, otherwise may be >0 to support meshes larger than 64K vertices with 16-bit indices. - unsigned int IdxOffset; // 4 // Start offset in index buffer. Always equal to sum of ElemCount drawn so far. + unsigned int IdxOffset; // 4 // Start offset in index buffer. unsigned int ElemCount; // 4 // Number of indices (multiple of 3) to be rendered as triangles. Vertices are stored in the callee ImDrawList's vtx_buffer[] array, indices in idx_buffer[]. ImDrawCallback UserCallback; // 4-8 // If != NULL, call the function instead of rendering the vertices. clip_rect and texture_id will be set normally. void* UserCallbackData; // 4-8 // The draw callback code can access this.