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.
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da04976437
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@ -100,13 +100,15 @@ static void InitScreenCoordinates(OutputVertex& vtx)
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void ProcessTriangle(OutputVertex &v0, OutputVertex &v1, OutputVertex &v2) {
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void ProcessTriangle(OutputVertex &v0, OutputVertex &v1, OutputVertex &v2) {
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using boost::container::static_vector;
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using boost::container::static_vector;
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// TODO (neobrain):
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// Clipping a planar n-gon against a plane will remove at least 1 vertex and introduces 2 at
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// The list of output vertices has some fixed maximum size,
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// the new edge (or less in degenerate cases). As such, we can say that each clipping plane
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// however I haven't taken the time to figure out what it is exactly.
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// introduces at most 1 new vertex to the polygon. Since we start with a triangle and have a
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// For now, we hence just assume a maximal size of 256 vertices.
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// fixed 6 clipping planes, the maximum number of vertices of the clipped polygon is 3 + 6 = 9.
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static const size_t MAX_VERTICES = 256;
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static const size_t MAX_VERTICES = 9;
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static_vector<OutputVertex, MAX_VERTICES> buffer_vertices;
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static_vector<OutputVertex, MAX_VERTICES> buffer_a = { v0, v1, v2 };
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static_vector<OutputVertex*, MAX_VERTICES> output_list = { &v0, &v1, &v2 };
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static_vector<OutputVertex, MAX_VERTICES> buffer_b;
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auto* output_list = &buffer_a;
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auto* input_list = &buffer_b;
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// Simple implementation of the Sutherland-Hodgman clipping algorithm.
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// Simple implementation of the Sutherland-Hodgman clipping algorithm.
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// TODO: Make this less inefficient (currently lots of useless buffering overhead happens here)
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// TODO: Make this less inefficient (currently lots of useless buffering overhead happens here)
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@ -117,48 +119,45 @@ void ProcessTriangle(OutputVertex &v0, OutputVertex &v1, OutputVertex &v2) {
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ClippingEdge(ClippingEdge::POS_Z, float24::FromFloat32(+1.0)),
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ClippingEdge(ClippingEdge::POS_Z, float24::FromFloat32(+1.0)),
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ClippingEdge(ClippingEdge::NEG_Z, float24::FromFloat32(-1.0)) }) {
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ClippingEdge(ClippingEdge::NEG_Z, float24::FromFloat32(-1.0)) }) {
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const static_vector<OutputVertex*, MAX_VERTICES> input_list = output_list;
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std::swap(input_list, output_list);
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output_list.clear();
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output_list->clear();
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const OutputVertex* reference_vertex = input_list.back();
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const OutputVertex* reference_vertex = &input_list->back();
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for (const auto& vertex : input_list) {
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for (const auto& vertex : *input_list) {
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// NOTE: This algorithm changes vertex order in some cases!
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// NOTE: This algorithm changes vertex order in some cases!
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if (edge.IsInside(*vertex)) {
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if (edge.IsInside(vertex)) {
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if (edge.IsOutSide(*reference_vertex)) {
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if (edge.IsOutSide(*reference_vertex)) {
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buffer_vertices.push_back(edge.GetIntersection(*vertex, *reference_vertex));
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output_list->push_back(edge.GetIntersection(vertex, *reference_vertex));
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output_list.push_back(&(buffer_vertices.back()));
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}
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}
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output_list.push_back(vertex);
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output_list->push_back(vertex);
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} else if (edge.IsInside(*reference_vertex)) {
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} else if (edge.IsInside(*reference_vertex)) {
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buffer_vertices.push_back(edge.GetIntersection(*vertex, *reference_vertex));
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output_list->push_back(edge.GetIntersection(vertex, *reference_vertex));
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output_list.push_back(&(buffer_vertices.back()));
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}
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}
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reference_vertex = &vertex;
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reference_vertex = vertex;
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}
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}
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// Need to have at least a full triangle to continue...
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// Need to have at least a full triangle to continue...
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if (output_list.size() < 3)
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if (output_list->size() < 3)
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return;
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return;
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}
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}
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InitScreenCoordinates(*(output_list[0]));
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InitScreenCoordinates((*output_list)[0]);
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InitScreenCoordinates(*(output_list[1]));
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InitScreenCoordinates((*output_list)[1]);
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for (size_t i = 0; i < output_list.size() - 2; i ++) {
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for (size_t i = 0; i < output_list->size() - 2; i ++) {
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OutputVertex& vtx0 = *(output_list[0]);
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OutputVertex& vtx0 = (*output_list)[0];
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OutputVertex& vtx1 = *(output_list[i+1]);
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OutputVertex& vtx1 = (*output_list)[i+1];
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OutputVertex& vtx2 = *(output_list[i+2]);
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OutputVertex& vtx2 = (*output_list)[i+2];
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InitScreenCoordinates(vtx2);
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InitScreenCoordinates(vtx2);
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LOG_TRACE(Render_Software,
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LOG_TRACE(Render_Software,
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"Triangle %lu/%lu (%lu buffer vertices) at position (%.3f, %.3f, %.3f, %.3f), "
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"Triangle %lu/%lu at position (%.3f, %.3f, %.3f, %.3f), "
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"(%.3f, %.3f, %.3f, %.3f), (%.3f, %.3f, %.3f, %.3f) and "
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"(%.3f, %.3f, %.3f, %.3f), (%.3f, %.3f, %.3f, %.3f) and "
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"screen position (%.2f, %.2f, %.2f), (%.2f, %.2f, %.2f), (%.2f, %.2f, %.2f)",
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"screen position (%.2f, %.2f, %.2f), (%.2f, %.2f, %.2f), (%.2f, %.2f, %.2f)",
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i,output_list.size(), buffer_vertices.size(),
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i, output_list->size(),
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vtx0.pos.x.ToFloat32(), vtx0.pos.y.ToFloat32(), vtx0.pos.z.ToFloat32(), vtx0.pos.w.ToFloat32(),
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vtx0.pos.x.ToFloat32(), vtx0.pos.y.ToFloat32(), vtx0.pos.z.ToFloat32(), vtx0.pos.w.ToFloat32(),
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vtx1.pos.x.ToFloat32(), vtx1.pos.y.ToFloat32(), vtx1.pos.z.ToFloat32(), vtx1.pos.w.ToFloat32(),
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vtx1.pos.x.ToFloat32(), vtx1.pos.y.ToFloat32(), vtx1.pos.z.ToFloat32(), vtx1.pos.w.ToFloat32(),
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vtx2.pos.x.ToFloat32(), vtx2.pos.y.ToFloat32(), vtx2.pos.z.ToFloat32(), vtx2.pos.w.ToFloat32(),
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vtx2.pos.x.ToFloat32(), vtx2.pos.y.ToFloat32(), vtx2.pos.z.ToFloat32(), vtx2.pos.w.ToFloat32(),
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