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366 lines
17 KiB
C++
366 lines
17 KiB
C++
// Copyright 2014 Citra Emulator Project
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// Licensed under GPLv2
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// Refer to the license.txt file included.
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#include <algorithm>
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#include "common/common_types.h"
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#include "math.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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#include "debug_utils/debug_utils.h"
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namespace Pica {
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namespace Rasterizer {
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static void DrawPixel(int x, int y, const Math::Vec4<u8>& color) {
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u32* color_buffer = (u32*)Memory::GetPointer(registers.framebuffer.GetColorBufferAddress());
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u32 value = (color.a() << 24) | (color.r() << 16) | (color.g() << 8) | color.b();
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// Assuming RGBA8 format until actual framebuffer format handling is implemented
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*(color_buffer + x + y * registers.framebuffer.GetWidth()) = value;
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}
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static u32 GetDepth(int x, int y) {
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u16* depth_buffer = (u16*)Memory::GetPointer(registers.framebuffer.GetDepthBufferAddress());
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// Assuming 16-bit depth buffer format until actual format handling is implemented
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return *(depth_buffer + x + y * registers.framebuffer.GetWidth());
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}
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static void SetDepth(int x, int y, u16 value) {
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u16* depth_buffer = (u16*)Memory::GetPointer(registers.framebuffer.GetDepthBufferAddress());
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// Assuming 16-bit depth buffer format until actual format handling is implemented
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*(depth_buffer + x + y * registers.framebuffer.GetWidth()) = value;
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}
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void ProcessTriangle(const VertexShader::OutputVertex& v0,
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const VertexShader::OutputVertex& v1,
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const VertexShader::OutputVertex& v2)
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{
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// NOTE: Assuming that rasterizer coordinates are 12.4 fixed-point values
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struct Fix12P4 {
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Fix12P4() {}
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Fix12P4(u16 val) : val(val) {}
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static u16 FracMask() { return 0xF; }
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static u16 IntMask() { return (u16)~0xF; }
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operator u16() const {
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return val;
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}
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bool operator < (const Fix12P4& oth) const {
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return (u16)*this < (u16)oth;
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}
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private:
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u16 val;
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};
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// vertex positions in rasterizer coordinates
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auto FloatToFix = [](float24 flt) {
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return Fix12P4(flt.ToFloat32() * 16.0f);
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};
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auto ScreenToRasterizerCoordinates = [FloatToFix](const Math::Vec3<float24> vec) {
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return Math::Vec3<Fix12P4>{FloatToFix(vec.x), FloatToFix(vec.y), FloatToFix(vec.z)};
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};
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Math::Vec3<Fix12P4> vtxpos[3]{ ScreenToRasterizerCoordinates(v0.screenpos),
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ScreenToRasterizerCoordinates(v1.screenpos),
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ScreenToRasterizerCoordinates(v2.screenpos) };
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// TODO: Proper scissor rect test!
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u16 min_x = std::min({vtxpos[0].x, vtxpos[1].x, vtxpos[2].x});
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u16 min_y = std::min({vtxpos[0].y, vtxpos[1].y, vtxpos[2].y});
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u16 max_x = std::max({vtxpos[0].x, vtxpos[1].x, vtxpos[2].x});
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u16 max_y = std::max({vtxpos[0].y, vtxpos[1].y, vtxpos[2].y});
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min_x &= Fix12P4::IntMask();
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min_y &= Fix12P4::IntMask();
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max_x = ((max_x + Fix12P4::FracMask()) & Fix12P4::IntMask());
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max_y = ((max_y + Fix12P4::FracMask()) & Fix12P4::IntMask());
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// Triangle filling rules: Pixels on the right-sided edge or on flat bottom edges are not
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// drawn. Pixels on any other triangle border are drawn. This is implemented with three bias
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// values which are added to the barycentric coordinates w0, w1 and w2, respectively.
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// NOTE: These are the PSP filling rules. Not sure if the 3DS uses the same ones...
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auto IsRightSideOrFlatBottomEdge = [](const Math::Vec2<Fix12P4>& vtx,
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const Math::Vec2<Fix12P4>& line1,
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const Math::Vec2<Fix12P4>& line2)
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{
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if (line1.y == line2.y) {
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// just check if vertex is above us => bottom line parallel to x-axis
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return vtx.y < line1.y;
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} else {
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// check if vertex is on our left => right side
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// TODO: Not sure how likely this is to overflow
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return (int)vtx.x < (int)line1.x + ((int)line2.x - (int)line1.x) * ((int)vtx.y - (int)line1.y) / ((int)line2.y - (int)line1.y);
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}
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};
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int bias0 = IsRightSideOrFlatBottomEdge(vtxpos[0].xy(), vtxpos[1].xy(), vtxpos[2].xy()) ? -1 : 0;
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int bias1 = IsRightSideOrFlatBottomEdge(vtxpos[1].xy(), vtxpos[2].xy(), vtxpos[0].xy()) ? -1 : 0;
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int bias2 = IsRightSideOrFlatBottomEdge(vtxpos[2].xy(), vtxpos[0].xy(), vtxpos[1].xy()) ? -1 : 0;
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// TODO: Not sure if looping through x first might be faster
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for (u16 y = min_y; y < max_y; y += 0x10) {
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for (u16 x = min_x; x < max_x; x += 0x10) {
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// Calculate the barycentric coordinates w0, w1 and w2
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auto orient2d = [](const Math::Vec2<Fix12P4>& vtx1,
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const Math::Vec2<Fix12P4>& vtx2,
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const Math::Vec2<Fix12P4>& vtx3) {
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const auto vec1 = Math::MakeVec(vtx2 - vtx1, 0);
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const auto vec2 = Math::MakeVec(vtx3 - vtx1, 0);
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// TODO: There is a very small chance this will overflow for sizeof(int) == 4
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return Math::Cross(vec1, vec2).z;
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};
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int w0 = bias0 + orient2d(vtxpos[1].xy(), vtxpos[2].xy(), {x, y});
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int w1 = bias1 + orient2d(vtxpos[2].xy(), vtxpos[0].xy(), {x, y});
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int w2 = bias2 + orient2d(vtxpos[0].xy(), vtxpos[1].xy(), {x, y});
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int wsum = w0 + w1 + w2;
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// If current pixel is not covered by the current primitive
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if (w0 < 0 || w1 < 0 || w2 < 0)
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continue;
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// Perspective correct attribute interpolation:
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// Attribute values cannot be calculated by simple linear interpolation since
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// they are not linear in screen space. For example, when interpolating a
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// texture coordinate across two vertices, something simple like
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// u = (u0*w0 + u1*w1)/(w0+w1)
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// will not work. However, the attribute value divided by the
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// clipspace w-coordinate (u/w) and and the inverse w-coordinate (1/w) are linear
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// in screenspace. Hence, we can linearly interpolate these two independently and
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// calculate the interpolated attribute by dividing the results.
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// I.e.
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// u_over_w = ((u0/v0.pos.w)*w0 + (u1/v1.pos.w)*w1)/(w0+w1)
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// one_over_w = (( 1/v0.pos.w)*w0 + ( 1/v1.pos.w)*w1)/(w0+w1)
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// u = u_over_w / one_over_w
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//
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// The generalization to three vertices is straightforward in baricentric coordinates.
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auto GetInterpolatedAttribute = [&](float24 attr0, float24 attr1, float24 attr2) {
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auto attr_over_w = Math::MakeVec(attr0 / v0.pos.w,
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attr1 / v1.pos.w,
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attr2 / v2.pos.w);
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auto w_inverse = Math::MakeVec(float24::FromFloat32(1.f) / v0.pos.w,
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float24::FromFloat32(1.f) / v1.pos.w,
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float24::FromFloat32(1.f) / v2.pos.w);
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auto baricentric_coordinates = Math::MakeVec(float24::FromFloat32(w0),
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float24::FromFloat32(w1),
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float24::FromFloat32(w2));
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float24 interpolated_attr_over_w = Math::Dot(attr_over_w, baricentric_coordinates);
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float24 interpolated_w_inverse = Math::Dot(w_inverse, baricentric_coordinates);
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return interpolated_attr_over_w / interpolated_w_inverse;
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};
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Math::Vec4<u8> primary_color{
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(u8)(GetInterpolatedAttribute(v0.color.r(), v1.color.r(), v2.color.r()).ToFloat32() * 255),
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(u8)(GetInterpolatedAttribute(v0.color.g(), v1.color.g(), v2.color.g()).ToFloat32() * 255),
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(u8)(GetInterpolatedAttribute(v0.color.b(), v1.color.b(), v2.color.b()).ToFloat32() * 255),
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(u8)(GetInterpolatedAttribute(v0.color.a(), v1.color.a(), v2.color.a()).ToFloat32() * 255)
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};
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Math::Vec4<u8> texture_color{};
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float24 u = GetInterpolatedAttribute(v0.tc0.u(), v1.tc0.u(), v2.tc0.u());
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float24 v = GetInterpolatedAttribute(v0.tc0.v(), v1.tc0.v(), v2.tc0.v());
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if (registers.texturing_enable) {
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// Images are split into 8x8 tiles. Each tile is composed of four 4x4 subtiles each
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// of which is composed of four 2x2 subtiles each of which is composed of four texels.
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// Each structure is embedded into the next-bigger one in a diagonal pattern, e.g.
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// texels are laid out in a 2x2 subtile like this:
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// 2 3
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// 0 1
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//
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// The full 8x8 tile has the texels arranged like this:
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//
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// 42 43 46 47 58 59 62 63
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// 40 41 44 45 56 57 60 61
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// 34 35 38 39 50 51 54 55
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// 32 33 36 37 48 49 52 53
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// 10 11 14 15 26 27 30 31
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// 08 09 12 13 24 25 28 29
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// 02 03 06 07 18 19 22 23
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// 00 01 04 05 16 17 20 21
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// TODO: This is currently hardcoded for RGB8
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u32* texture_data = (u32*)Memory::GetPointer(registers.texture0.GetPhysicalAddress());
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// TODO(neobrain): Not sure if this swizzling pattern is used for all textures.
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// To be flexible in case different but similar patterns are used, we keep this
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// somewhat inefficient code around for now.
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int s = (int)(u * float24::FromFloat32(registers.texture0.width)).ToFloat32();
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int t = (int)(v * float24::FromFloat32(registers.texture0.height)).ToFloat32();
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int texel_index_within_tile = 0;
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for (int block_size_index = 0; block_size_index < 3; ++block_size_index) {
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int sub_tile_width = 1 << block_size_index;
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int sub_tile_height = 1 << block_size_index;
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int sub_tile_index = (s & sub_tile_width) << block_size_index;
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sub_tile_index += 2 * ((t & sub_tile_height) << block_size_index);
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texel_index_within_tile += sub_tile_index;
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}
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const int block_width = 8;
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const int block_height = 8;
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int coarse_s = (s / block_width) * block_width;
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int coarse_t = (t / block_height) * block_height;
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const int row_stride = registers.texture0.width * 3;
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u8* source_ptr = (u8*)texture_data + coarse_s * block_height * 3 + coarse_t * row_stride + texel_index_within_tile * 3;
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texture_color.r() = source_ptr[2];
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texture_color.g() = source_ptr[1];
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texture_color.b() = source_ptr[0];
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texture_color.a() = 0xFF;
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DebugUtils::DumpTexture(registers.texture0, (u8*)texture_data);
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}
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// Texture environment - consists of 6 stages of color and alpha combining.
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//
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// Color combiners take three input color values from some source (e.g. interpolated
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// vertex color, texture color, previous stage, etc), perform some very simple
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// operations on each of them (e.g. inversion) and then calculate the output color
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// with some basic arithmetic. Alpha combiners can be configured separately but work
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// analogously.
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Math::Vec4<u8> combiner_output;
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for (auto tev_stage : registers.GetTevStages()) {
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using Source = Regs::TevStageConfig::Source;
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using ColorModifier = Regs::TevStageConfig::ColorModifier;
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using AlphaModifier = Regs::TevStageConfig::AlphaModifier;
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using Operation = Regs::TevStageConfig::Operation;
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auto GetColorSource = [&](Source source) -> Math::Vec3<u8> {
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switch (source) {
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case Source::PrimaryColor:
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return primary_color.rgb();
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case Source::Texture0:
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return texture_color.rgb();
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case Source::Constant:
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return {tev_stage.const_r, tev_stage.const_g, tev_stage.const_b};
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case Source::Previous:
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return combiner_output.rgb();
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default:
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ERROR_LOG(GPU, "Unknown color combiner source %d\n", (int)source);
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return {};
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}
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};
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auto GetAlphaSource = [&](Source source) -> u8 {
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switch (source) {
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case Source::PrimaryColor:
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return primary_color.a();
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case Source::Texture0:
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return texture_color.a();
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case Source::Constant:
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return tev_stage.const_a;
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case Source::Previous:
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return combiner_output.a();
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default:
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ERROR_LOG(GPU, "Unknown alpha combiner source %d\n", (int)source);
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return 0;
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}
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};
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auto GetColorModifier = [](ColorModifier factor, const Math::Vec3<u8>& values) -> Math::Vec3<u8> {
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switch (factor)
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{
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case ColorModifier::SourceColor:
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return values;
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default:
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ERROR_LOG(GPU, "Unknown color factor %d\n", (int)factor);
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return {};
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}
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};
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auto GetAlphaModifier = [](AlphaModifier factor, u8 value) -> u8 {
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switch (factor) {
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case AlphaModifier::SourceAlpha:
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return value;
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default:
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ERROR_LOG(GPU, "Unknown color factor %d\n", (int)factor);
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return 0;
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}
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};
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auto ColorCombine = [](Operation op, const Math::Vec3<u8> input[3]) -> Math::Vec3<u8> {
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switch (op) {
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case Operation::Replace:
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return input[0];
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case Operation::Modulate:
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return ((input[0] * input[1]) / 255).Cast<u8>();
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default:
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ERROR_LOG(GPU, "Unknown color combiner operation %d\n", (int)op);
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return {};
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}
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};
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auto AlphaCombine = [](Operation op, const std::array<u8,3>& input) -> u8 {
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switch (op) {
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case Operation::Replace:
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return input[0];
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case Operation::Modulate:
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return input[0] * input[1] / 255;
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default:
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ERROR_LOG(GPU, "Unknown alpha combiner operation %d\n", (int)op);
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return 0;
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}
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};
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// color combiner
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// NOTE: Not sure if the alpha combiner might use the color output of the previous
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// stage as input. Hence, we currently don't directly write the result to
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// combiner_output.rgb(), but instead store it in a temporary variable until
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// alpha combining has been done.
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Math::Vec3<u8> color_result[3] = {
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GetColorModifier(tev_stage.color_modifier1, GetColorSource(tev_stage.color_source1)),
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GetColorModifier(tev_stage.color_modifier2, GetColorSource(tev_stage.color_source2)),
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GetColorModifier(tev_stage.color_modifier3, GetColorSource(tev_stage.color_source3))
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};
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auto color_output = ColorCombine(tev_stage.color_op, color_result);
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// alpha combiner
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std::array<u8,3> alpha_result = {
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GetAlphaModifier(tev_stage.alpha_modifier1, GetAlphaSource(tev_stage.alpha_source1)),
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GetAlphaModifier(tev_stage.alpha_modifier2, GetAlphaSource(tev_stage.alpha_source2)),
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GetAlphaModifier(tev_stage.alpha_modifier3, GetAlphaSource(tev_stage.alpha_source3))
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};
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auto alpha_output = AlphaCombine(tev_stage.alpha_op, alpha_result);
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combiner_output = Math::MakeVec(color_output, alpha_output);
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}
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// TODO: Not sure if the multiplication by 65535 has already been taken care
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// of when transforming to screen coordinates or not.
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u16 z = (u16)(((float)v0.screenpos[2].ToFloat32() * w0 +
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(float)v1.screenpos[2].ToFloat32() * w1 +
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(float)v2.screenpos[2].ToFloat32() * w2) * 65535.f / wsum);
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SetDepth(x >> 4, y >> 4, z);
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DrawPixel(x >> 4, y >> 4, combiner_output);
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}
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}
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}
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} // namespace Rasterizer
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} // namespace Pica
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