void RenderViewMLGPU::AddItemFrontToBack(LayerMLGPU* aLayer, ItemInfo& aItem) {
// We receive items in front-to-back order. Ideally we want to push items
// as far back into batches impossible, to ensure the GPU can do a good
// job at culling. However we also want to make sure we actually batch
// items versus drawing one primitive per pass.
//
// As a compromise we look at the most 3 recent batches and then give up.
// This can be tweaked in the future.
static const size_t kMaxSearch = 3;
size_t iterations = 0;
for (auto iter = mFrontToBack.rbegin(); iter != mFrontToBack.rend(); iter++) {
RenderPassMLGPU* pass = (*iter);
if (pass->IsCompatible(aItem) && pass->AcceptItem(aItem)) {
AL_LOG("RenderView %p added layer %p to pass %p (%d)\n", this,
aLayer->GetLayer(), pass, int(pass->GetType()));
return;
}
if (++iterations > kMaxSearch) {
break;
}
}
RefPtr<RenderPassMLGPU> pass = RenderPassMLGPU::CreatePass(mBuilder, aItem);
if (!pass || !pass->AcceptItem(aItem)) {
MOZ_ASSERT_UNREACHABLE("Could not build a pass for item!");
return;
}
AL_LOG("RenderView %p added layer %p to new pass %p (%d)\n", this,
aLayer->GetLayer(), pass.get(), int(pass->GetType()));
mFrontToBack.push_back(pass);
}
void RenderViewMLGPU::AddItemBackToFront(LayerMLGPU* aLayer, ItemInfo& aItem) {
// We receive layers in front-to-back order, but there are two cases when we
// actually draw back-to-front: when the depth buffer is disabled, or when
// using the depth buffer and the item has transparent pixels (and therefore
// requires blending). In these cases we will build vertex and constant
// buffers in reverse, as well as execute batches in reverse, to ensure the
// correct ordering.
//
// Note: We limit the number of batches we search through, since it's better
// to add new draw calls than spend too much time finding compatible
// batches further down.
static const size_t kMaxSearch = 10;
size_t iterations = 0;
for (auto iter = mBackToFront.begin(); iter != mBackToFront.end(); iter++) {
RenderPassMLGPU* pass = (*iter);
if (pass->IsCompatible(aItem) && pass->AcceptItem(aItem)) {
AL_LOG("RenderView %p added layer %p to pass %p (%d)\n", this,
aLayer->GetLayer(), pass, int(pass->GetType()));
return;
}
if (pass->Intersects(aItem)) {
break;
}
if (++iterations > kMaxSearch) {
break;
}
}
RefPtr<RenderPassMLGPU> pass = RenderPassMLGPU::CreatePass(mBuilder, aItem);
if (!pass || !pass->AcceptItem(aItem)) {
MOZ_ASSERT_UNREACHABLE("Could not build a pass for item!");
return;
}
AL_LOG("RenderView %p added layer %p to new pass %p (%d)\n", this,
aLayer->GetLayer(), pass.get(), int(pass->GetType()));
mBackToFront.push_front(pass);
}