PICA: Implement scissor test

1 files changed, 21 insertions, 1 deletions

diff --git a/src/video_core/rasterizer.cpp b/src/video_core/rasterizer.cpp
index a84170094..514d64208 100644
--- a/src/video_core/rasterizer.cpp
+++ b/src/video_core/rasterizer.cpp
@@ -338,12 +338,25 @@ static void ProcessTriangleInternal(const Shader::OutputVertex& v0,
             return;
     }
 
-    // TODO: Proper scissor rect test!
     u16 min_x = std::min({vtxpos[0].x, vtxpos[1].x, vtxpos[2].x});
     u16 min_y = std::min({vtxpos[0].y, vtxpos[1].y, vtxpos[2].y});
     u16 max_x = std::max({vtxpos[0].x, vtxpos[1].x, vtxpos[2].x});
     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);
+
+    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 &= Fix12P4::IntMask();
     min_y &= Fix12P4::IntMask();
     max_x = ((max_x + Fix12P4::FracMask()) & Fix12P4::IntMask());
@@ -383,6 +396,13 @@ static void ProcessTriangleInternal(const Shader::OutputVertex& v0,
     for (u16 y = min_y + 8; y < max_y; y += 0x10) {
         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;
+            }
+
             // Calculate the barycentric coordinates w0, w1 and w2
             int w0 = bias0 + SignedArea(vtxpos[1].xy(), vtxpos[2].xy(), {x, y});
             int w1 = bias1 + SignedArea(vtxpos[2].xy(), vtxpos[0].xy(), {x, y});