// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2
// Refer to the license.txt file included.
#include <vector>
#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(registers.viewport_corner.x);
viewport.offset_y = float24::FromFloat32(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) {
// 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 1000 vertices.
const size_t max_vertices = 1000;
std::vector<OutputVertex> buffer_vertices;
std::vector<OutputVertex*> output_list{ &v0, &v1, &v2 };
// Make sure to reserve space for all vertices.
// Without this, buffer reallocation would invalidate references.
buffer_vertices.reserve(max_vertices);
// 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)) }) {
const std::vector<OutputVertex*> 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)) {
buffer_vertices.push_back(edge.GetIntersection(*vertex, *reference_vertex));
output_list.push_back(&(buffer_vertices.back()));
}
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()));
}
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 (int 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);
DEBUG_LOG(GPU,
"Triangle %d/%d (%d buffer vertices) 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(),
vtx0.pos.x.ToFloat32(), vtx0.pos.y.ToFloat32(), vtx0.pos.z.ToFloat32(), vtx0.pos.w.ToFloat32(),output_list.size(),
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
