365236fa4c
The change in depth range seems to reflect better to what applications are expecting, and makes for cleaner code overall (hence is more likely to reflect hardware behavior).
171 lines
7 KiB
C++
171 lines
7 KiB
C++
// Copyright 2014 Citra Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <boost/container/static_vector.hpp>
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#include "clipper.h"
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#include "pica.h"
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#include "rasterizer.h"
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#include "vertex_shader.h"
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namespace Pica {
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namespace Clipper {
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struct ClippingEdge {
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public:
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ClippingEdge(Math::Vec4<float24> coeffs,
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Math::Vec4<float24> bias = Math::Vec4<float24>(float24::FromFloat32(0),
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float24::FromFloat32(0),
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float24::FromFloat32(0),
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float24::FromFloat32(0)))
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: coeffs(coeffs),
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bias(bias)
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{
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}
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bool IsInside(const OutputVertex& vertex) const {
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return Math::Dot(vertex.pos + bias, coeffs) <= float24::FromFloat32(0);
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}
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bool IsOutSide(const OutputVertex& vertex) const {
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return !IsInside(vertex);
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}
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OutputVertex GetIntersection(const OutputVertex& v0, const OutputVertex& v1) const {
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float24 dp = Math::Dot(v0.pos + bias, coeffs);
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float24 dp_prev = Math::Dot(v1.pos + bias, coeffs);
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float24 factor = dp_prev / (dp_prev - dp);
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return OutputVertex::Lerp(factor, v0, v1);
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}
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private:
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float24 pos;
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Math::Vec4<float24> coeffs;
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Math::Vec4<float24> bias;
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};
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static void InitScreenCoordinates(OutputVertex& vtx)
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{
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struct {
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float24 halfsize_x;
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float24 offset_x;
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float24 halfsize_y;
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float24 offset_y;
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float24 zscale;
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float24 offset_z;
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} viewport;
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viewport.halfsize_x = float24::FromRawFloat24(registers.viewport_size_x);
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viewport.halfsize_y = float24::FromRawFloat24(registers.viewport_size_y);
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viewport.offset_x = float24::FromFloat32(static_cast<float>(registers.viewport_corner.x));
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viewport.offset_y = float24::FromFloat32(static_cast<float>(registers.viewport_corner.y));
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viewport.zscale = float24::FromRawFloat24(registers.viewport_depth_range);
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viewport.offset_z = float24::FromRawFloat24(registers.viewport_depth_far_plane);
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float24 inv_w = float24::FromFloat32(1.f) / vtx.pos.w;
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vtx.color *= inv_w;
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vtx.tc0 *= inv_w;
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vtx.tc1 *= inv_w;
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vtx.tc2 *= inv_w;
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vtx.pos.w = inv_w;
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vtx.screenpos[0] = (vtx.pos.x * inv_w + float24::FromFloat32(1.0)) * viewport.halfsize_x + viewport.offset_x;
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vtx.screenpos[1] = (vtx.pos.y * inv_w + float24::FromFloat32(1.0)) * viewport.halfsize_y + viewport.offset_y;
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vtx.screenpos[2] = viewport.offset_z + vtx.pos.z * inv_w * viewport.zscale;
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}
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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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// Clipping a planar n-gon against a plane will remove at least 1 vertex and introduces 2 at
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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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// introduces at most 1 new vertex to the polygon. Since we start with a triangle and have a
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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 = 9;
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static_vector<OutputVertex, MAX_VERTICES> buffer_a = { 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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// NOTE: We clip against a w=epsilon plane to guarantee that the output has a positive w value.
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// TODO: Not sure if this is a valid approach. Also should probably instead use the smallest
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// epsilon possible within float24 accuracy.
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static const float24 EPSILON = float24::FromFloat32(0.00001);
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static const float24 f0 = float24::FromFloat32(0.0);
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static const float24 f1 = float24::FromFloat32(1.0);
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static const std::array<ClippingEdge, 7> clipping_edges = {{
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{ Math::MakeVec( f1, f0, f0, -f1) }, // x = +w
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{ Math::MakeVec(-f1, f0, f0, -f1) }, // x = -w
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{ Math::MakeVec( f0, f1, f0, -f1) }, // y = +w
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{ Math::MakeVec( f0, -f1, f0, -f1) }, // y = -w
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{ Math::MakeVec( f0, f0, f1, f0) }, // z = 0
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{ Math::MakeVec( f0, f0, -f1, -f1) }, // z = -w
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{ Math::MakeVec( f0, f0, f0, -f1), Math::Vec4<float24>(f0, f0, f0, EPSILON) }, // w = EPSILON
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}};
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// TODO: If one vertex lies outside one of the depth clipping planes, some platforms (e.g. Wii)
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// drop the whole primitive instead of clipping the primitive properly. We should test if
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// this happens on the 3DS, too.
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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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for (auto edge : clipping_edges) {
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std::swap(input_list, output_list);
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output_list->clear();
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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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// NOTE: This algorithm changes vertex order in some cases!
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if (edge.IsInside(vertex)) {
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if (edge.IsOutSide(*reference_vertex)) {
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output_list->push_back(edge.GetIntersection(vertex, *reference_vertex));
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}
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output_list->push_back(vertex);
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} else if (edge.IsInside(*reference_vertex)) {
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output_list->push_back(edge.GetIntersection(vertex, *reference_vertex));
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}
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reference_vertex = &vertex;
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}
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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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return;
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}
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InitScreenCoordinates((*output_list)[0]);
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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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OutputVertex& vtx0 = (*output_list)[0];
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OutputVertex& vtx1 = (*output_list)[i+1];
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OutputVertex& vtx2 = (*output_list)[i+2];
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InitScreenCoordinates(vtx2);
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LOG_TRACE(Render_Software,
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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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"screen position (%.2f, %.2f, %.2f), (%.2f, %.2f, %.2f), (%.2f, %.2f, %.2f)",
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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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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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vtx0.screenpos.x.ToFloat32(), vtx0.screenpos.y.ToFloat32(), vtx0.screenpos.z.ToFloat32(),
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vtx1.screenpos.x.ToFloat32(), vtx1.screenpos.y.ToFloat32(), vtx1.screenpos.z.ToFloat32(),
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vtx2.screenpos.x.ToFloat32(), vtx2.screenpos.y.ToFloat32(), vtx2.screenpos.z.ToFloat32());
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Rasterizer::ProcessTriangle(vtx0, vtx1, vtx2);
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}
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}
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} // namespace
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} // namespace
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