// Typically, 1 command = 1 GPU draw call (unless command is a callback)
// Pre 1.71 back-ends will typically ignore the VtxOffset/IdxOffset fields. When 'io.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset'
// is enabled, those fields allow us to render meshes larger than 64K vertices while keeping 16-bit indices.
// - 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 back-ends will typically ignore the VtxOffset/IdxOffset fields.
// - The ClipRect/TextureId/VtxOffset fields must be contiguous as we memcmp() them together (this is asserted for).
structImDrawCmd
{
unsignedintElemCount;// 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[].
ImVec4ClipRect;// 4*4 // Clipping rectangle (x1, y1, x2, y2). Subtract ImDrawData->DisplayPos to get clipping rectangle in "viewport" coordinates
ImTextureIDTextureId;// 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.
unsignedintVtxOffset;// 4 // Start offset in vertex buffer. Pre-1.71 or without ImGuiBackendFlags_RendererHasVtxOffset: always 0. With ImGuiBackendFlags_RendererHasVtxOffset: may be >0 to support meshes larger than 64K vertices with 16-bit indices.
unsignedintVtxOffset;// 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.
unsignedintIdxOffset;// 4 // Start offset in index buffer. Always equal to sum of ElemCount drawn so far.
unsignedintElemCount;// 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[].
ImDrawCallbackUserCallback;// 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.
ImVector<ImVec2>_Path;// [Internal] current path building
ImDrawCmd_CmdHeader;// [Internal] Template of active commands. Fields should match those of CmdBuffer.back().
ImDrawListSplitter_Splitter;// [Internal] for channels api (note: prefer using your own persistent instance of ImDrawListSplitter!)
// If you want to create ImDrawList instances, pass them ImGui::GetDrawListSharedData() or create and use your own ImDrawListSharedData (so you can use ImDrawList without ImGui)
IMGUI_APIvoidPushClipRect(ImVec2clip_rect_min,ImVec2clip_rect_max,boolintersect_with_current_clip_rect=false);// Render-level scissoring. This is passed down to your render function but not used for CPU-side coarse clipping. Prefer using higher-level ImGui::PushClipRect() to affect logic (hit-testing and widget culling)
// Our scheme may appears a bit unusual, basically we want the most-common calls AddLine AddRect etc. to not have to perform any check so we always have a command ready in the stack.
// The cost of figuring out if a new command has to be added or if we can merge is paid in those Update** functions only.
voidImDrawList::UpdateClipRect()
{
// If current command is used with different settings we need to add a new command
// Render-level scissoring. This is passed down to your render function but not used for CPU-side coarse clipping. Prefer using higher-level ImGui::PushClipRect() to affect logic (hit-testing and widget culling)
IM_ASSERT(font->ContainerAtlas->TexID==_TextureIdStack.back());// Use high-level ImGui::PushFont() or low-level ImDrawList::PushTextureId() to change font.
IM_ASSERT(font->ContainerAtlas->TexID==_CmdHeader.TextureId);// Use high-level ImGui::PushFont() or low-level ImDrawList::PushTextureId() to change font.
ocornut
5 years ago