From 516143b170059dcb24fcb28714a7eae4cce5db1e Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Wed, 12 Apr 2017 21:07:39 -0700
Subject: [PATCH] DS GX: Allow viewport to change in the middle of a frame

---
 CHANGES                       |  1 +
 include/mgba/internal/ds/gx.h | 10 +++++-----
 src/ds/gx.c                   |  8 ++++----
 src/ds/gx/software.c          | 12 ++++++------
 4 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/CHANGES b/CHANGES
index ceeefbbfd..bf32459d7 100644
--- a/CHANGES
+++ b/CHANGES
@@ -18,6 +18,7 @@ Bugfixes:
  - DS Video: Fix affine transformations in video capture
  - DS GX: Fix bitmap textures when no palette is mapped (fixes mgba.io/i/628)
  - DS GX: Don't reset state between buffer swaps (fixes mgba.io/i/642)
+ - DS GX: Allow viewport to change in the middle of a frame
 Misc:
  - DS: Set boot complete bit in RAM on boot (fixes mgba.io/i/576, mgba.io/i/580, mgba.io/i/586)
  - DS Memory: Ensure DS9 I/O is 8-byte aligned
diff --git a/include/mgba/internal/ds/gx.h b/include/mgba/internal/ds/gx.h
index c3eff83cc..fc745a2f0 100644
--- a/include/mgba/internal/ds/gx.h
+++ b/include/mgba/internal/ds/gx.h
@@ -120,6 +120,11 @@ struct DSGXVertex {
 	int32_t viewCoord[4];
 	int16_t vs; // 12.4
 	int16_t vt; // 12.4
+
+	int viewportX;
+	int viewportY;
+	int viewportWidth;
+	int viewportHeight;
 };
 
 struct DSGXPolygon {
@@ -143,11 +148,6 @@ struct DSGXRenderer {
 
 	uint16_t* tex[4];
 	uint16_t* texPal[6];
-
-	int viewportX;
-	int viewportY;
-	int viewportWidth;
-	int viewportHeight;
 };
 
 struct DSGXLight {
diff --git a/src/ds/gx.c b/src/ds/gx.c
index 4b5caf2c5..e30cd7c7f 100644
--- a/src/ds/gx.c
+++ b/src/ds/gx.c
@@ -1180,10 +1180,10 @@ static void _fifoRun(struct mTiming* timing, void* context, uint32_t cyclesLate)
 			gx->viewportY2 = (uint8_t) entry.params[3];
 			gx->viewportWidth = gx->viewportX2 - gx->viewportX1 + 1;
 			gx->viewportHeight = gx->viewportY2 - gx->viewportY1 + 1;
-			gx->renderer->viewportX = gx->viewportX1;
-			gx->renderer->viewportY = gx->viewportY1;
-			gx->renderer->viewportWidth = gx->viewportWidth;
-			gx->renderer->viewportHeight = gx->viewportHeight;
+			gx->currentVertex.viewportX = gx->viewportX1;
+			gx->currentVertex.viewportY = gx->viewportY1;
+			gx->currentVertex.viewportWidth = gx->viewportWidth;
+			gx->currentVertex.viewportHeight = gx->viewportHeight;
 			break;
 		case DS_GX_CMD_BOX_TEST:
 			gxstat = DSRegGXSTATClearTestBusy(gxstat);
diff --git a/src/ds/gx/software.c b/src/ds/gx/software.c
index 653b3f3eb..d8cedf97b 100644
--- a/src/ds/gx/software.c
+++ b/src/ds/gx/software.c
@@ -487,8 +487,8 @@ static void _preparePoly(struct DSGXRenderer* renderer, struct DSGXVertex* verts
 		v0w = 1;
 	}
 
-	int32_t v0x = (v0->viewCoord[0] + v0w) * (int64_t) (renderer->viewportWidth << 12) / (v0w * 2) + (renderer->viewportX << 12);
-	int32_t v0y = (-v0->viewCoord[1] + v0w) * (int64_t) (renderer->viewportHeight << 12) / (v0w * 2) + (renderer->viewportY << 12);
+	int32_t v0x = (v0->viewCoord[0] + v0w) * (int64_t) (v0->viewportWidth << 12) / (v0w * 2) + (v0->viewportX << 12);
+	int32_t v0y = (-v0->viewCoord[1] + v0w) * (int64_t) (v0->viewportHeight << 12) / (v0w * 2) + (v0->viewportY << 12);
 	if (poly->minY > v0y >> 12) {
 		poly->minY = v0y >> 12;
 	}
@@ -504,8 +504,8 @@ static void _preparePoly(struct DSGXRenderer* renderer, struct DSGXVertex* verts
 		if (!v1w) {
 			v1w = 1;
 		}
-		int32_t v1x = (v1->viewCoord[0] + v1w) * (int64_t) (renderer->viewportWidth << 12) / (v1w * 2) + (renderer->viewportX << 12);
-		int32_t v1y = (-v1->viewCoord[1] + v1w) * (int64_t) (renderer->viewportHeight << 12) / (v1w * 2) + (renderer->viewportY << 12);
+		int32_t v1x = (v1->viewCoord[0] + v1w) * (int64_t) (v1->viewportWidth << 12) / (v1w * 2) + (v1->viewportX << 12);
+		int32_t v1y = (-v1->viewCoord[1] + v1w) * (int64_t) (v1->viewportHeight << 12) / (v1w * 2) + (v1->viewportY << 12);
 		if (poly->minY > v1y >> 12) {
 			poly->minY = v1y >> 12;
 		}
@@ -563,8 +563,8 @@ static void _preparePoly(struct DSGXRenderer* renderer, struct DSGXVertex* verts
 	if (!v1w) {
 		v1w = 1;
 	}
-	int32_t v1x = (v1->viewCoord[0] + v1w) * (int64_t) (renderer->viewportWidth << 12) / (v1w * 2) + (renderer->viewportX << 12);
-	int32_t v1y = (-v1->viewCoord[1] + v1w) * (int64_t) (renderer->viewportHeight << 12) / (v1w * 2) + (renderer->viewportY << 12);
+	int32_t v1x = (v1->viewCoord[0] + v1w) * (int64_t) (v1->viewportWidth << 12) / (v1w * 2) + (v1->viewportX << 12);
+	int32_t v1y = (-v1->viewCoord[1] + v1w) * (int64_t) (v1->viewportHeight << 12) / (v1w * 2) + (v1->viewportY << 12);
 
 	if (poly->minY > v1y >> 12) {
 		poly->minY = v1y >> 12;