gpu: refactored polygon command to output valid struct

src/device/gpu/gpu.cpp

@@ -46,60 +46,32 @@ void GPU::reset() {
     gp0_e6._reg = 0;
 }
 
-void GPU::drawPolygon(int16_t x[4], int16_t y[4], RGB c[4], TextureInfo t, bool isQuad, bool textured, int flags) {
-    int baseX = 0, baseY = 0, clutX = 0, clutY = 0, bitcount = 0;
-
-    for (int i = 0; i < (isQuad ? 4 : 3); i++) {
-        x[i] += drawingOffsetX;
-        y[i] += drawingOffsetY;
-    }
-
-    if (textured) {
-        clutX = t.getClutX();
-        clutY = t.getClutY();
-        baseX = t.getBaseX();
-        baseY = t.getBaseY();
-        bitcount = t.getBitcount();
-        flags |= ((int)t.semiTransparencyBlending()) << 5;
-    } else {
-        flags |= ((int)gp0_e1.semiTransparency) << 5;
+void GPU::drawTriangle(const primitive::Triangle& triangle) {
+    if (hardwareRendering) {
+        int flags = 0;
+        if (triangle.isSemiTransparent) flags |= Vertex::Flags::SemiTransparency;
+        if (triangle.isRawTexture) flags |= Vertex::Flags::RawTexture;
+        if (gp0_e1.dither24to15) flags |= Vertex::Flags::Dithering;
+        if (triangle.gouroudShading) flags |= Vertex::Flags::GouroudShading;
+        flags |= static_cast<int>(triangle.transparency) << 5;
+
+        for (int i : {0, 1, 2}) {
+            auto& v = triangle.v[i];
+            vertices.push_back({Vertex::Type::Polygon,
+                                {v.pos.x + drawingOffsetX, v.pos.y + drawingOffsetY},
+                                {v.color.r, v.color.g, v.color.b},
+                                {v.uv.x, v.uv.y},
+                                triangle.bits,
+                                {triangle.clut.x, triangle.clut.y},
+                                {triangle.texpage.x, triangle.texpage.y},
+                                flags,
+                                gp0_e2,
+                                gp0_e6});
+        }
     }
 
-    Vertex v[3];
-    for (int i : {0, 1, 2}) {
-        v[i] = {Vertex::Type::Polygon,
-                {x[i], y[i]},
-                {c[i].r, c[i].g, c[i].b},
-                {t.uv[i].x, t.uv[i].y},
-                bitcount,
-                {clutX, clutY},
-                {baseX, baseY},
-                flags,
-                gp0_e2,
-                gp0_e6};
-        vertices.push_back(v[i]);
-    }
     if (softwareRendering) {
-        Render::drawTriangle(this, v);
-    }
-
-    if (isQuad) {
-        for (int i : {1, 2, 3}) {
-            v[i - 1] = {Vertex::Type::Polygon,
-                        {x[i], y[i]},
-                        {c[i].r, c[i].g, c[i].b},
-                        {t.uv[i].x, t.uv[i].y},
-                        bitcount,
-                        {clutX, clutY},
-                        {baseX, baseY},
-                        flags,
-                        gp0_e2,
-                        gp0_e6};
-            vertices.push_back(v[i - 1]);
-        }
-        if (softwareRendering) {
-            Render::drawTriangle(this, v);
-        }
+        Render::drawTriangle(this, triangle);
     }
 }
 
@@ -241,29 +213,53 @@ void GPU::cmdFillRectangle(uint8_t command) {
 
 void GPU::cmdPolygon(PolygonArgs arg) {
     int ptr = 1;
-    int16_t x[4], y[4];
-    RGB c[4] = {};
+
+    primitive::Triangle::Vertex v[4];
     TextureInfo tex;
+
     for (int i = 0; i < arg.getVertexCount(); i++) {
-        x[i] = extend_sign<10>(arguments[ptr] & 0xffff);
-        y[i] = extend_sign<10>((arguments[ptr++] & 0xffff0000) >> 16);
+        v[i].pos.x = extend_sign<10>(arguments[ptr] & 0xffff);
+        v[i].pos.y = extend_sign<10>((arguments[ptr++] & 0xffff0000) >> 16);
 
-        if (!arg.isRawTexture && (!arg.gouroudShading || i == 0)) c[i].raw = arguments[0] & 0xffffff;
+        if (!arg.isRawTexture && (!arg.gouroudShading || i == 0)) v[i].color.raw = arguments[0] & 0xffffff;
         if (arg.isTextureMapped) {
             if (i == 0) tex.palette = arguments[ptr];
             if (i == 1) tex.texpage = arguments[ptr];
-            tex.uv[i].x = arguments[ptr] & 0xff;
-            tex.uv[i].y = (arguments[ptr] >> 8) & 0xff;
+            v[i].uv.x = arguments[ptr] & 0xff;
+            v[i].uv.y = (arguments[ptr] >> 8) & 0xff;
             ptr++;
         }
-        if (arg.gouroudShading && i < arg.getVertexCount() - 1) c[i + 1].raw = arguments[ptr++];
+        if (arg.gouroudShading && i < arg.getVertexCount() - 1) v[i + 1].color.raw = arguments[ptr++] & 0xffffff;
+    }
+
+    primitive::Triangle triangle;
+
+    for (int i : {0, 1, 2}) triangle.v[i] = v[i];
+
+    triangle.bits = 0;
+    triangle.isSemiTransparent = arg.semiTransparency;
+    triangle.transparency = gp0_e1.semiTransparency;
+    triangle.isRawTexture = arg.isRawTexture;
+    triangle.gouroudShading = arg.gouroudShading;
+
+    if (arg.isTextureMapped) {
+        triangle.bits = tex.getBitcount();
+        triangle.texpage.x = tex.getBaseX();
+        triangle.texpage.y = tex.getBaseY();
+        triangle.clut.x = tex.getClutX();
+        triangle.clut.y = tex.getClutY();
+        triangle.transparency = tex.semiTransparencyBlending();
+    }
+
+    triangle.assureCcw();
+    drawTriangle(triangle);
+
+    if (arg.isQuad) {
+        for (int i : {1, 2, 3}) triangle.v[i - 1] = v[i];
+
+        triangle.assureCcw();
+        drawTriangle(triangle);
     }
-    int flags = 0;
-    if (arg.semiTransparency) flags |= Vertex::SemiTransparency;
-    if (arg.isRawTexture) flags |= Vertex::RawTexture;
-    if (arg.gouroudShading) flags |= Vertex::GouroudShading;
-    if (gp0_e1.dither24to15) flags |= Vertex::Dithering;
-    drawPolygon(x, y, c, tex, arg.isQuad, arg.isTextureMapped, flags);
 
     cmd = Command::None;
 }

src/device/gpu/gpu.h

@@ -106,7 +106,7 @@ class GPU {
     void cmdVramToCpu(uint8_t command);
     void cmdVramToVram(uint8_t command);
 
-    void drawPolygon(int16_t x[4], int16_t y[4], RGB c[4], TextureInfo t, bool isQuad = false, bool textured = false, int flags = 0);
+    void drawTriangle(const primitive::Triangle& triangle);
     void drawLine(const primitive::Line& line);
     void drawRectangle(const primitive::Rect& rect);
 

src/device/gpu/primitive.h

@@ -1,5 +1,7 @@
 #pragma once
 #include <glm/glm.hpp>
+#include <utility>
+#include "device/gpu/semi_transparency.h"
 #include "psx_color.h"
 
 namespace primitive {
@@ -27,4 +29,39 @@ struct Line {
     bool isSemiTransparent;
     bool gouroudShading;
 };
+
+struct Triangle {
+    struct Vertex {
+        glm::ivec2 pos;
+        RGB color;      // Valid if bits == 0 or !isRawTexture
+        glm::ivec2 uv;  // Valid if bits != 0
+    };
+    Vertex v[3];
+
+    // Flags
+    int bits = 0;
+    gpu::SemiTransparency transparency;  // Valid if isSemiTransparent
+    bool isSemiTransparent = false;
+    bool isRawTexture = false;
+    bool gouroudShading = false;
+
+    // Texture, valid if bits != 0
+    glm::ivec2 texpage;  // Texture page position in VRAM
+    glm::ivec2 clut;     // Texture palette position in VRAM
+
+    void assureCcw() {
+        if (isCw()) {
+            std::swap(v[1], v[2]);
+        }
+    }
+
+   private:
+    bool isCw() const {
+        auto ab = v[1].pos - v[0].pos;
+        auto ac = v[2].pos - v[0].pos;
+        auto cross = ab.x * ac.y - ab.y * ac.x;
+
+        return cross < 0;
+    }
+};
 }  // namespace primitive

src/device/gpu/psx_color.h

@@ -13,6 +13,8 @@ union RGB {
         uint8_t _;
     };
     uint32_t raw;
+
+    RGB() : raw(0) {}
 };
 
 RGB operator*(const RGB& lhs, const float rhs);

src/device/gpu/registers.h

@@ -1,5 +1,6 @@
 #pragma once
 #include "device/device.h"
+#include "semi_transparency.h"
 
 namespace gpu {
 
@@ -8,12 +9,6 @@ const int MAX_ARGS = 32;
 
 // Draw Mode setting
 union GP0_E1 {
-    enum class SemiTransparency : uint32_t {
-        Bby2plusFby2 = 0,  // B/2+F/2
-        BplusF = 1,        // B+F
-        BminusF = 2,       // B-F
-        BplusFby4 = 3      // B+F/4
-    };
     enum class TexturePageColors : uint32_t { bit4 = 0, bit8 = 1, bit15 = 2 };
     enum class DrawingToDisplayArea : uint32_t { prohibited = 0, allowed = 1 };
     struct {
@@ -248,12 +243,8 @@ struct TextureInfo {
 
     int getClutX() const { return ((palette & 0x003f0000) >> 16) * 16; }
     int getClutY() const { return ((palette & 0x7fc00000) >> 22); }
-    int getBaseX() const {
-        return ((texpage & 0x0f0000) >> 16) * 64;  // N * 64
-    }
-    int getBaseY() const {
-        return ((texpage & 0x100000) >> 20) * 256;  // N * 256
-    }
+    int getBaseX() const { return ((texpage & 0x0f0000) >> 16) * 64; }   // N * 64
+    int getBaseY() const { return ((texpage & 0x100000) >> 20) * 256; }  // N * 256
     int getBitcount() const {
         int depth = (texpage & 0x1800000) >> 23;
         switch (depth) {
@@ -265,7 +256,7 @@ struct TextureInfo {
         }
     }
 
-    GP0_E1::SemiTransparency semiTransparencyBlending() const { return (GP0_E1::SemiTransparency)((texpage & 0x600000) >> 21); }
+    SemiTransparency semiTransparencyBlending() const { return (SemiTransparency)((texpage & 0x600000) >> 21); }
 };
 
 // Debug/rewind

src/device/gpu/render/render.h

@@ -4,6 +4,6 @@
 class Render {
    public:
     static void drawLine(gpu::GPU* gpu, const primitive::Line& line);
-    static void drawTriangle(gpu::GPU* gpu, gpu::Vertex v[3]);
+    static void drawTriangle(gpu::GPU* gpu, const primitive::Triangle& triangle);
     static void drawRectangle(gpu::GPU* gpu, const primitive::Rect& rect);
 };

src/device/gpu/render/render_line.cpp

@@ -7,7 +7,7 @@
 #define VRAM ((uint16_t(*)[gpu::VRAM_WIDTH])gpu->vram.data())
 
 void Render::drawLine(gpu::GPU* gpu, const primitive::Line& line) {
-    using Transparency = gpu::GP0_E1::SemiTransparency;
+    using Transparency = gpu::SemiTransparency;
     const auto transparency = gpu->gp0_e1.semiTransparency;
     const bool checkMaskBeforeDraw = gpu->gp0_e6.checkMaskBeforeDraw;
     const bool setMaskWhileDrawing = gpu->gp0_e6.setMaskWhileDrawing;