PICA: Scissor fixes and cleanups

src/video_core/pica.h

@@ -128,22 +128,14 @@ struct Regs {
         BitField<0, 2, ScissorMode> mode;
 
         union {
-            BitField< 0, 16, u32> right;
-            BitField<16, 16, u32> bottom;
+            BitField< 0, 16, u32> x1;
+            BitField<16, 16, u32> y1;
         };
 
         union {
-            BitField< 0, 16, u32> left_minus_1;
-            BitField<16, 16, u32> top_minus_1;
+            BitField< 0, 16, u32> x2;
+            BitField<16, 16, u32> y2;
         };
-
-        u32 GetTop() const {
-            return top_minus_1 + 1;
-        }
-
-        u32 GetLeft() const {
-            return left_minus_1 + 1;
-        }
     } scissor_test;
 
     union {

src/video_core/rasterizer.cpp

@@ -344,17 +344,18 @@ static void ProcessTriangleInternal(const Shader::OutputVertex& v0,
     u16 max_y = std::max({vtxpos[0].y, vtxpos[1].y, vtxpos[2].y});
 
     // Convert the scissor box coordinates to 12.4 fixed point
-    u16 scissor_left = (u16)(regs.scissor_test.GetLeft() << 4);
-    u16 scissor_top = (u16)(regs.scissor_test.GetTop() << 4);
-    u16 scissor_right = (u16)(regs.scissor_test.right << 4);
-    u16 scissor_bottom = (u16)(regs.scissor_test.bottom << 4);
+    u16 scissor_x1 = (u16)( regs.scissor_test.x1      << 4);
+    u16 scissor_y1 = (u16)( regs.scissor_test.y1      << 4);
+    // x2,y2 have +1 added to cover the entire sub-pixel area
+    u16 scissor_x2 = (u16)((regs.scissor_test.x2 + 1) << 4);
+    u16 scissor_y2 = (u16)((regs.scissor_test.y2 + 1) << 4);
 
     if (regs.scissor_test.mode == Regs::ScissorMode::Include) {
         // Calculate the new bounds
-        min_x = std::max(min_x, scissor_right);
-        min_y = std::max(min_y, scissor_bottom);
-        max_x = std::min(max_x, scissor_left);
-        max_y = std::min(max_y, scissor_top);
+        min_x = std::max(min_x, scissor_x1);
+        min_y = std::max(min_y, scissor_y1);
+        max_x = std::min(max_x, scissor_x2);
+        max_y = std::min(max_y, scissor_y2);
     }
 
     min_x &= Fix12P4::IntMask();
@@ -397,10 +398,10 @@ static void ProcessTriangleInternal(const Shader::OutputVertex& v0,
         for (u16 x = min_x + 8; x < max_x; x += 0x10) {
 
             // Do not process the pixel if it's inside the scissor box and the scissor mode is set to Exclude
-            if (regs.scissor_test.mode == Regs::ScissorMode::Exclude &&
-                x >= scissor_right && x <= scissor_left &&
-                y >= scissor_bottom && y <= scissor_top) {
-                continue;
+            if (regs.scissor_test.mode == Regs::ScissorMode::Exclude) {
+                if (x >= scissor_x1 && x < scissor_x2 &&
+                    y >= scissor_y1 && y < scissor_y2)
+                    continue;
             }
 
             // Calculate the barycentric coordinates w0, w1 and w2

src/video_core/renderer_opengl/gl_rasterizer.cpp

@@ -357,8 +357,8 @@ void RasterizerOpenGL::NotifyPicaRegisterChanged(u32 id) {
     case PICA_REG_INDEX(scissor_test.mode):
         shader_dirty = true;
         break;
-    case PICA_REG_INDEX(scissor_test.right):
-    case PICA_REG_INDEX(scissor_test.left_minus_1):
+    case PICA_REG_INDEX(scissor_test.x1): // and y1
+    case PICA_REG_INDEX(scissor_test.x2): // and y2
         SyncScissorTest();
         break;
 
@@ -1179,15 +1179,15 @@ void RasterizerOpenGL::SyncDepthTest() {
 void RasterizerOpenGL::SyncScissorTest() {
     const auto& regs = Pica::g_state.regs;
 
-    if (uniform_block_data.data.scissor_right != regs.scissor_test.right ||
-        uniform_block_data.data.scissor_bottom != regs.scissor_test.bottom ||
-        uniform_block_data.data.scissor_left != regs.scissor_test.GetLeft() ||
-        uniform_block_data.data.scissor_top != regs.scissor_test.GetTop()) {
+    if (uniform_block_data.data.scissor_x1 != regs.scissor_test.x1 ||
+        uniform_block_data.data.scissor_y1 != regs.scissor_test.y1 ||
+        uniform_block_data.data.scissor_x2 != regs.scissor_test.x2 ||
+        uniform_block_data.data.scissor_y2 != regs.scissor_test.y2) {
 
-        uniform_block_data.data.scissor_right = regs.scissor_test.right;
-        uniform_block_data.data.scissor_bottom = regs.scissor_test.bottom;
-        uniform_block_data.data.scissor_left = regs.scissor_test.GetLeft();
-        uniform_block_data.data.scissor_top = regs.scissor_test.GetTop();
+        uniform_block_data.data.scissor_x1 = regs.scissor_test.x1;
+        uniform_block_data.data.scissor_y1 = regs.scissor_test.y1;
+        uniform_block_data.data.scissor_x2 = regs.scissor_test.x2;
+        uniform_block_data.data.scissor_y2 = regs.scissor_test.y2;
         uniform_block_data.dirty = true;
     }
 }

src/video_core/renderer_opengl/gl_rasterizer.h

@@ -331,10 +331,10 @@ private:
         GLint alphatest_ref;
         GLfloat depth_scale;
         GLfloat depth_offset;
-        GLint scissor_right;
-        GLint scissor_bottom;
-        GLint scissor_left;
-        GLint scissor_top;
+        GLint scissor_x1;
+        GLint scissor_y1;
+        GLint scissor_x2;
+        GLint scissor_y2;
         alignas(16) GLvec3 fog_color;
         alignas(16) GLvec3 lighting_global_ambient;
         LightSrc light_src[8];

src/video_core/renderer_opengl/gl_shader_gen.cpp

@@ -557,10 +557,10 @@ layout (std140) uniform shader_data {
     int alphatest_ref;
     float depth_scale;
     float depth_offset;
-    int scissor_right;
-    int scissor_bottom;
-    int scissor_left;
-    int scissor_top;
+    int scissor_x1;
+    int scissor_y1;
+    int scissor_x2;
+    int scissor_y2;
     vec3 fog_color;
     vec3 lighting_global_ambient;
     LightSrc light_src[NUM_LIGHTS];
@@ -589,13 +589,14 @@ vec4 secondary_fragment_color = vec4(0.0);
     }
 
     // Append the scissor test
-    if (state.scissor_test_mode == Regs::ScissorMode::Include || state.scissor_test_mode == Regs::ScissorMode::Exclude) {
-        out += "if (scissor_left <= scissor_right || scissor_top <= scissor_bottom) discard;\n";
+    if (state.scissor_test_mode != Regs::ScissorMode::Disabled) {
         out += "if (";
         // Negate the condition if we have to keep only the pixels outside the scissor box
         if (state.scissor_test_mode == Regs::ScissorMode::Include)
             out += "!";
-        out += "(gl_FragCoord.x >= scissor_right && gl_FragCoord.x <= scissor_left && gl_FragCoord.y >= scissor_bottom && gl_FragCoord.y <= scissor_top)) discard;\n";
+        // x2,y2 have +1 added to cover the entire pixel area
+        out += "(gl_FragCoord.x >= scissor_x1 && gl_FragCoord.x < scissor_x2 + 1 && "
+                "gl_FragCoord.y >= scissor_y1 && gl_FragCoord.y < scissor_y2 + 1)) discard;\n";
     }
 
     out += "float z_over_w = 1.0 - gl_FragCoord.z * 2.0;\n";