184 lines
7.2 KiB
C++
184 lines
7.2 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 <algorithm>
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#include <array>
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#include <cstddef>
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#include <boost/container/static_vector.hpp>
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#include <boost/container/vector.hpp>
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#include "common/bit_field.h"
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#include "common/common_types.h"
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#include "common/logging/log.h"
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#include "common/vector_math.h"
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#include "video_core/clipper.h"
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#include "video_core/pica.h"
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#include "video_core/pica_state.h"
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#include "video_core/pica_types.h"
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#include "video_core/rasterizer.h"
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#include "video_core/shader/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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const auto& regs = g_state.regs;
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viewport.halfsize_x = float24::FromRaw(regs.viewport_size_x);
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viewport.halfsize_y = float24::FromRaw(regs.viewport_size_y);
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viewport.offset_x = float24::FromFloat32(static_cast<float>(regs.viewport_corner.x));
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viewport.offset_y = float24::FromFloat32(static_cast<float>(regs.viewport_corner.y));
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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.view *= inv_w;
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vtx.quat *= 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] = vtx.pos.z * inv_w;
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}
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void ProcessTriangle(const OutputVertex &v0, const OutputVertex &v1, const 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(0.00001f);
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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 + 1, output_list->size() - 2,
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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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