ImDrawListSplitter: extracted out of ImDrawList. Down the line we may obsolete the ImDrawList functions and encourage users to store the splitter aside, in the meanwhile ImDrawList holds a splitter.
// Draw channels are used by the Columns API to "split" the render list into different channels while building, so items of each column can be batched together.
// You can also use them to simulate drawing layers and submit primitives in a different order than how they will be rendered.
// For use by ImDrawListSplitter.
structImDrawChannel
{
ImVector<ImDrawCmd>CmdBuffer;
ImVector<ImDrawIdx>IdxBuffer;
ImVector<ImDrawCmd>CmdBuffer;
ImVector<ImDrawIdx>IdxBuffer;
};
// Split/Merge functions are used to split the draw list into different layers which can be drawn into out of order.
// This is used by the Columns api, so items of each column can be batched together in a same draw call.
structImDrawListSplitter
{
int_Current;// Current channel number (0)
int_Count;// Number of active channels (1+)
ImVector<ImDrawChannel>_Channels;// Draw channels (not resized down so Count might be < Channels.Size)
inlineImDrawListSplitter(){Clear();}
inlinevoidClear(){_Current=0;_Count=1;}// Do not clear Channels[] so our allocations are reused next frame
// This is the low-level list of polygons that ImGui functions are filling. At the end of the frame, all command lists are passed to your ImGuiIO::RenderDrawListFn function for rendering.
// Each ImGui window contains its own ImDrawList. You can use ImGui::GetWindowDrawList() to access the current window draw list and draw custom primitives.
// This is the low-level list of polygons that ImGui:: functions are filling. At the end of the frame,
// all command lists are passed to your ImGuiIO::RenderDrawListFn function for rendering.
// Each dear imgui window contains its own ImDrawList. You can use ImGui::GetWindowDrawList() to
// access the current window draw list and draw custom primitives.
// You can interleave normal ImGui:: calls and adding primitives to the current draw list.
// All positions are generally in pixel coordinates (top-left at (0,0), bottom-right at io.DisplaySize), but you are totally free to apply whatever transformation matrix to want to the data (if you apply such transformation you'll want to apply it to ClipRect as well)
// Important: Primitives are always added to the list and not culled (culling is done at higher-level by ImGui:: functions), if you use this API a lot consider coarse culling your drawn objects.
ImVector<ImVec2>_Path;// [Internal] current path building
int_ChannelsCurrent;// [Internal] current channel number (0)
int_ChannelsCount;// [Internal] number of active channels (1+)
ImVector<ImDrawChannel>_Channels;// [Internal] draw channels for columns API (not resized down so _ChannelsCount may be smaller than _Channels.Size)
ImDrawListSplitter_Splitter;// [Internal] for channels api
// 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)
// - Use to simulate layers. By switching channels to can render out-of-order (e.g. submit foreground primitives before background primitives)
// - Use to minimize draw calls (e.g. if going back-and-forth between multiple non-overlapping clipping rectangles, prefer to append into separate channels then merge at the end)
IMGUI_APIvoidAddCallback(ImDrawCallbackcallback,void*callback_data);// Your rendering function must check for 'UserCallback' in ImDrawCmd and call the function instead of rendering triangles.
IMGUI_APIvoidAddDrawCmd();// This is useful if you need to forcefully create a new draw call (to allow for dependent rendering / blending). Otherwise primitives are merged into the same draw-call as much as possible
IMGUI_APIImDrawList*CloneOutput()const;// Create a clone of the CmdBuffer/IdxBuffer/VtxBuffer.
// Advanced: Channels
// - Use to split render into layers. By switching channels to can render out-of-order (e.g. submit foreground primitives before background primitives)
// - Use to minimize draw calls (e.g. if going back-and-forth between multiple non-overlapping clipping rectangles, prefer to append into separate channels then merge at the end)
// Channels[] (24/32 bytes each) hold storage that we'll swap with draw_list->_CmdBuffer/_IdxBuffer
// The content of Channels[0] at this point doesn't matter. We clear it to make state tidy in a debugger but we don't strictly need to.
// When we switch to the next channel, we'll copy draw_list->_CmdBuffer/_IdxBuffer into Channels[0] and then Channels[1] into draw_list->CmdBuffer/_IdxBuffer
omar
6 years ago