diff options
Diffstat (limited to 'src/video_core/clipper.cpp')
| -rw-r--r-- | src/video_core/clipper.cpp | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/src/video_core/clipper.cpp b/src/video_core/clipper.cpp new file mode 100644 index 000000000..b7180328c --- /dev/null +++ b/src/video_core/clipper.cpp @@ -0,0 +1,179 @@ +// 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 / float24::FromFloat32(2.0) + 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 |