From 7e9bc85cc826c55a5aa612a3c2f14b8fb631a68c Mon Sep 17 00:00:00 2001 From: Yuri Kunde Schlesner Date: Sun, 28 Dec 2014 23:05:15 -0200 Subject: [PATCH] Clipper: Compact buffers on each clipping pass Use a new buffer management scheme in the clipper that allows using a bounded minimal amount of buffer space. Even though it copies more data it is still slightly faster likely due to using less cache. --- src/video_core/clipper.cpp | 55 +++++++++++++++++++------------------- 1 file changed, 27 insertions(+), 28 deletions(-) diff --git a/src/video_core/clipper.cpp b/src/video_core/clipper.cpp index e89b7a0c0e..0521ef8661 100644 --- a/src/video_core/clipper.cpp +++ b/src/video_core/clipper.cpp @@ -100,13 +100,15 @@ static void InitScreenCoordinates(OutputVertex& vtx) void ProcessTriangle(OutputVertex &v0, OutputVertex &v1, OutputVertex &v2) { using boost::container::static_vector; - // TODO (neobrain): - // The list of output vertices has some fixed maximum size, - // however I haven't taken the time to figure out what it is exactly. - // For now, we hence just assume a maximal size of 256 vertices. - static const size_t MAX_VERTICES = 256; - static_vector buffer_vertices; - static_vector output_list = { &v0, &v1, &v2 }; + // Clipping a planar n-gon against a plane will remove at least 1 vertex and introduces 2 at + // the new edge (or less in degenerate cases). As such, we can say that each clipping plane + // introduces at most 1 new vertex to the polygon. Since we start with a triangle and have a + // fixed 6 clipping planes, the maximum number of vertices of the clipped polygon is 3 + 6 = 9. + static const size_t MAX_VERTICES = 9; + static_vector buffer_a = { v0, v1, v2 }; + static_vector buffer_b; + auto* output_list = &buffer_a; + auto* input_list = &buffer_b; // Simple implementation of the Sutherland-Hodgman clipping algorithm. // TODO: Make this less inefficient (currently lots of useless buffering overhead happens here) @@ -117,48 +119,45 @@ void ProcessTriangle(OutputVertex &v0, OutputVertex &v1, OutputVertex &v2) { ClippingEdge(ClippingEdge::POS_Z, float24::FromFloat32(+1.0)), ClippingEdge(ClippingEdge::NEG_Z, float24::FromFloat32(-1.0)) }) { - const static_vector input_list = output_list; - output_list.clear(); + std::swap(input_list, output_list); + output_list->clear(); - const OutputVertex* reference_vertex = input_list.back(); + const OutputVertex* reference_vertex = &input_list->back(); - for (const auto& vertex : input_list) { + for (const auto& vertex : *input_list) { // NOTE: This algorithm changes vertex order in some cases! - if (edge.IsInside(*vertex)) { + if (edge.IsInside(vertex)) { if (edge.IsOutSide(*reference_vertex)) { - buffer_vertices.push_back(edge.GetIntersection(*vertex, *reference_vertex)); - output_list.push_back(&(buffer_vertices.back())); + output_list->push_back(edge.GetIntersection(vertex, *reference_vertex)); } - output_list.push_back(vertex); + output_list->push_back(vertex); } else if (edge.IsInside(*reference_vertex)) { - buffer_vertices.push_back(edge.GetIntersection(*vertex, *reference_vertex)); - output_list.push_back(&(buffer_vertices.back())); + output_list->push_back(edge.GetIntersection(vertex, *reference_vertex)); } - - reference_vertex = vertex; + reference_vertex = &vertex; } // Need to have at least a full triangle to continue... - if (output_list.size() < 3) + if (output_list->size() < 3) return; } - InitScreenCoordinates(*(output_list[0])); - InitScreenCoordinates(*(output_list[1])); + InitScreenCoordinates((*output_list)[0]); + InitScreenCoordinates((*output_list)[1]); - for (size_t i = 0; i < output_list.size() - 2; i ++) { - OutputVertex& vtx0 = *(output_list[0]); - OutputVertex& vtx1 = *(output_list[i+1]); - OutputVertex& vtx2 = *(output_list[i+2]); + for (size_t i = 0; i < output_list->size() - 2; i ++) { + OutputVertex& vtx0 = (*output_list)[0]; + OutputVertex& vtx1 = (*output_list)[i+1]; + OutputVertex& vtx2 = (*output_list)[i+2]; InitScreenCoordinates(vtx2); LOG_TRACE(Render_Software, - "Triangle %lu/%lu (%lu buffer vertices) at position (%.3f, %.3f, %.3f, %.3f), " + "Triangle %lu/%lu at position (%.3f, %.3f, %.3f, %.3f), " "(%.3f, %.3f, %.3f, %.3f), (%.3f, %.3f, %.3f, %.3f) and " "screen position (%.2f, %.2f, %.2f), (%.2f, %.2f, %.2f), (%.2f, %.2f, %.2f)", - i,output_list.size(), buffer_vertices.size(), + i, output_list->size(), vtx0.pos.x.ToFloat32(), vtx0.pos.y.ToFloat32(), vtx0.pos.z.ToFloat32(), vtx0.pos.w.ToFloat32(), vtx1.pos.x.ToFloat32(), vtx1.pos.y.ToFloat32(), vtx1.pos.z.ToFloat32(), vtx1.pos.w.ToFloat32(), vtx2.pos.x.ToFloat32(), vtx2.pos.y.ToFloat32(), vtx2.pos.z.ToFloat32(), vtx2.pos.w.ToFloat32(),