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// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <boost/container/static_vector.hpp>
#include "clipper.h"
#include "pica.h"
#include "rasterizer.h"
#include "vertex_shader.h"
namespace Pica {
namespace Clipper {
struct ClippingEdge {
public:
enum Type {
POS_X = 0,
NEG_X = 1,
POS_Y = 2,
NEG_Y = 3,
POS_Z = 4,
NEG_Z = 5,
};
ClippingEdge(Type type, float24 position) : type(type), pos(position) {}
bool IsInside(const OutputVertex& vertex) const {
switch (type) {
case POS_X: return vertex.pos.x <= pos * vertex.pos.w;
case NEG_X: return vertex.pos.x >= pos * vertex.pos.w;
case POS_Y: return vertex.pos.y <= pos * vertex.pos.w;
case NEG_Y: return vertex.pos.y >= pos * vertex.pos.w;
// TODO: Check z compares ... should be 0..1 instead?
case POS_Z: return vertex.pos.z <= pos * vertex.pos.w;
default:
case NEG_Z: return vertex.pos.z >= pos * vertex.pos.w;
}
}
bool IsOutSide(const OutputVertex& vertex) const {
return !IsInside(vertex);
}
OutputVertex GetIntersection(const OutputVertex& v0, const OutputVertex& v1) const {
auto dotpr = [this](const OutputVertex& vtx) {
switch (type) {
case POS_X: return vtx.pos.x - vtx.pos.w;
case NEG_X: return -vtx.pos.x - vtx.pos.w;
case POS_Y: return vtx.pos.y - vtx.pos.w;
case NEG_Y: return -vtx.pos.y - vtx.pos.w;
// TODO: Verify z clipping
case POS_Z: return vtx.pos.z - vtx.pos.w;
default:
case NEG_Z: return -vtx.pos.w;
}
};
float24 dp = dotpr(v0);
float24 dp_prev = dotpr(v1);
float24 factor = dp_prev / (dp_prev - dp);
return OutputVertex::Lerp(factor, v0, v1);
}
private:
Type type;
float24 pos;
};
static void InitScreenCoordinates(OutputVertex& vtx)
{
struct {
float24 halfsize_x;
float24 offset_x;
float24 halfsize_y;
float24 offset_y;
float24 zscale;
float24 offset_z;
} viewport;
viewport.halfsize_x = float24::FromRawFloat24(registers.viewport_size_x);
viewport.halfsize_y = float24::FromRawFloat24(registers.viewport_size_y);
viewport.offset_x = float24::FromFloat32(static_cast<float>(registers.viewport_corner.x));
viewport.offset_y = float24::FromFloat32(static_cast<float>(registers.viewport_corner.y));
viewport.zscale = float24::FromRawFloat24(registers.viewport_depth_range);
viewport.offset_z = float24::FromRawFloat24(registers.viewport_depth_far_plane);
// TODO: Not sure why the viewport width needs to be divided by 2 but the viewport height does not
vtx.screenpos[0] = (vtx.pos.x / vtx.pos.w + float24::FromFloat32(1.0)) * viewport.halfsize_x + viewport.offset_x;
vtx.screenpos[1] = (vtx.pos.y / vtx.pos.w + float24::FromFloat32(1.0)) * viewport.halfsize_y + viewport.offset_y;
vtx.screenpos[2] = viewport.offset_z - vtx.pos.z / vtx.pos.w * viewport.zscale;
}
void ProcessTriangle(OutputVertex &v0, OutputVertex &v1, OutputVertex &v2) {
using boost::container::static_vector;
// 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<OutputVertex, MAX_VERTICES> buffer_a = { v0, v1, v2 };
static_vector<OutputVertex, MAX_VERTICES> 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)
for (auto edge : { ClippingEdge(ClippingEdge::POS_X, float24::FromFloat32(+1.0)),
ClippingEdge(ClippingEdge::NEG_X, float24::FromFloat32(-1.0)),
ClippingEdge(ClippingEdge::POS_Y, float24::FromFloat32(+1.0)),
ClippingEdge(ClippingEdge::NEG_Y, float24::FromFloat32(-1.0)),
ClippingEdge(ClippingEdge::POS_Z, float24::FromFloat32(+1.0)),
ClippingEdge(ClippingEdge::NEG_Z, float24::FromFloat32(-1.0)) }) {
std::swap(input_list, output_list);
output_list->clear();
const OutputVertex* reference_vertex = &input_list->back();
for (const auto& vertex : *input_list) {
// NOTE: This algorithm changes vertex order in some cases!
if (edge.IsInside(vertex)) {
if (edge.IsOutSide(*reference_vertex)) {
output_list->push_back(edge.GetIntersection(vertex, *reference_vertex));
}
output_list->push_back(vertex);
} else if (edge.IsInside(*reference_vertex)) {
output_list->push_back(edge.GetIntersection(vertex, *reference_vertex));
}
reference_vertex = &vertex;
}
// Need to have at least a full triangle to continue...
if (output_list->size() < 3)
return;
}
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];
InitScreenCoordinates(vtx2);
LOG_TRACE(Render_Software,
"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(),
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(),
vtx0.screenpos.x.ToFloat32(), vtx0.screenpos.y.ToFloat32(), vtx0.screenpos.z.ToFloat32(),
vtx1.screenpos.x.ToFloat32(), vtx1.screenpos.y.ToFloat32(), vtx1.screenpos.z.ToFloat32(),
vtx2.screenpos.x.ToFloat32(), vtx2.screenpos.y.ToFloat32(), vtx2.screenpos.z.ToFloat32());
Rasterizer::ProcessTriangle(vtx0, vtx1, vtx2);
}
}
} // namespace
} // namespace
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