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ImDrawListSplitter: Support merging consecutive draw commands straddling two channels. Support zero-init.

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This commit is contained in:
omar 2019-05-10 18:50:59 +02:00
parent f1f4b42d91
commit cef88f6aae
1 changed files with 16 additions and 2 deletions
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18
imgui_draw.cpp
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@ -1213,7 +1213,7 @@ void ImDrawListSplitter::ClearFreeMemory()
void ImDrawListSplitter::Split(ImDrawList* draw_list, int channels_count)
{
IM_ASSERT(_Current == 0 && _Count == 1);
IM_ASSERT(_Current == 0 && _Count <= 1);
int old_channels_count = _Channels.Size;
if (old_channels_count < channels_count)
_Channels.resize(channels_count);
@ -1244,6 +1244,11 @@ void ImDrawListSplitter::Split(ImDrawList* draw_list, int channels_count)
}
}
static inline bool CanMergeDrawCommands(ImDrawCmd* a, ImDrawCmd* b)
{
return memcmp(&a->ClipRect, &b->ClipRect, sizeof(a->ClipRect)) == 0 && a->TextureId == b->TextureId && !a->UserCallback && !b->UserCallback;
}
void ImDrawListSplitter::Merge(ImDrawList* draw_list)
{
// Note that we never use or rely on channels.Size because it is merely a buffer that we never shrink back to 0 to keep all sub-buffers ready for use.
@ -1257,12 +1262,21 @@ void ImDrawListSplitter::Merge(ImDrawList* draw_list)
// Calculate our final buffer sizes. Also fix the incorrect IdxOffset values in each command.
int new_cmd_buffer_count = 0;
int new_idx_buffer_count = 0;
int idx_offset = (draw_list->CmdBuffer.Size != 0) ? (draw_list->CmdBuffer.back().IdxOffset + draw_list->CmdBuffer.back().ElemCount) : 0;
ImDrawCmd* last_cmd = (_Count > 0 && _Channels[0].CmdBuffer.Size > 0) ? &_Channels[0].CmdBuffer.back() : NULL;
int idx_offset = last_cmd ? last_cmd->IdxOffset + last_cmd->ElemCount : 0;
for (int i = 1; i < _Count; i++)
{
ImDrawChannel& ch = _Channels[i];
if (ch.CmdBuffer.Size && ch.CmdBuffer.back().ElemCount == 0)
ch.CmdBuffer.pop_back();
else if (ch.CmdBuffer.Size > 0 && last_cmd != NULL && CanMergeDrawCommands(last_cmd, &ch.CmdBuffer[0]))
{
// Merge previous channel last draw command with current channel first draw command if matching.
last_cmd->ElemCount += ch.CmdBuffer[0].ElemCount;
ch.CmdBuffer.erase(ch.CmdBuffer.Data);
}
if (ch.CmdBuffer.Size > 0)
last_cmd = &ch.CmdBuffer.back();
new_cmd_buffer_count += ch.CmdBuffer.Size;
new_idx_buffer_count += ch.IdxBuffer.Size;
for (int cmd_n = 0; cmd_n < ch.CmdBuffer.Size; cmd_n++)