M include/mgba/internal/ds/gx/software.h → include/mgba/internal/ds/gx/software.h

@@ -36,6 +36,7 @@ int32_t y0; // 20.12
 	int32_t x0; // 20.12
 	int32_t z0; // 20.12
 	int32_t w0; // 20.12
+	int64_t wr0;
 	uint8_t cr0;
 	uint8_t cg0;
 	uint8_t cb0;
@@ -46,6 +47,7 @@ int32_t y1; // 20.12
 	int32_t x1; // 20.12
 	int32_t z1; // 20.12
 	int32_t w1; // 20.12
+	int64_t wr1;
 	uint8_t cr1;
 	uint8_t cg1;
 	uint8_t cb1;

M src/ds/gx/software.c → src/ds/gx/software.c

@@ -313,8 +313,8 @@ index = 0;
 		}
 	}
 
-	int64_t w0 = 0x7FFFFFFFFFFFFFFF / edge->w0;
-	int64_t w1 = 0x7FFFFFFFFFFFFFFF / edge->w1;
+	int64_t w0 = edge->wr0;
+	int64_t w1 = edge->wr1;
 	int64_t w = w1 - w0;
 
 	// Losslessly interpolate two 64-bit values
@@ -526,6 +526,8 @@ _expandColor(v0->color, &edge->cr1, &edge->cg1, &edge->cb1);
 			edge->s1 = v0->vs;
 			edge->t1 = v0->vt;
 		}
+		edge->wr0 = 0x7FFFFFFFFFFFFFFF / edge->w0;
+		edge->wr1 = 0x7FFFFFFFFFFFFFFF / edge->w1;
 
 		edge = DSGXSoftwareEdgeListAppend(&softwareRenderer->activeEdges);
 		edge->polyId = poly->polyId;
@@ -578,6 +580,8 @@ _expandColor(v0->color, &edge->cr1, &edge->cg1, &edge->cb1);
 		edge->s1 = v0->vs;
 		edge->t1 = v0->vt;
 	}
+	edge->wr0 = 0x7FFFFFFFFFFFFFFF / edge->w0;
+	edge->wr1 = 0x7FFFFFFFFFFFFFFF / edge->w1;
 
 	if (poly->maxY >= DS_VIDEO_VERTICAL_PIXELS) {
 		poly->maxY = DS_VIDEO_VERTICAL_PIXELS - 1;