From 6509c4fffac8c593aa4515ab29b36b1ef6b26e3e Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Mon, 17 Jul 2017 14:49:32 -0700
Subject: [PATCH] DS GX: Clear depth

---
 CHANGES                                |  1 +
 README.md                              |  1 -
 include/mgba/internal/ds/gx/software.h |  1 +
 src/ds/gx.c                            |  1 +
 src/ds/gx/software.c                   | 13 +++++++++----
 5 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/CHANGES b/CHANGES
index 2d8136431..6c770ee98 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,7 @@
 medusa alpha 3 (Future)
 Features:
  - DS GX: Toon shading
+ - DS GX: Clear depth
 Bugfixes:
  - DS GX: Fix vertex texture transformation (fixes mgba.io/i/702)
  - DS GX: Automatically normalize winding culling calculations (fixes mgba.io/i/699)
diff --git a/README.md b/README.md
index 154a17bab..bd1a176dd 100644
--- a/README.md
+++ b/README.md
@@ -182,7 +182,6 @@ Missing features on DS are
 	- Edge marking/wireframe
 	- Highlight shading
 	- Fog
-	- Clear depth
 	- Anti-aliasing
 	- Alpha test
 	- Position test
diff --git a/include/mgba/internal/ds/gx/software.h b/include/mgba/internal/ds/gx/software.h
index 6249f8740..40fc29e31 100644
--- a/include/mgba/internal/ds/gx/software.h
+++ b/include/mgba/internal/ds/gx/software.h
@@ -95,6 +95,7 @@ struct DSGXSoftwareRenderer {
 	int sort;
 	uint16_t clearStencil;
 	color_t clearColor;
+	uint32_t clearDepth;
 	bool flushPending;
 
 	struct DSGXVertex* verts;
diff --git a/src/ds/gx.c b/src/ds/gx.c
index 336b5efef..304a93c38 100644
--- a/src/ds/gx.c
+++ b/src/ds/gx.c
@@ -1326,6 +1326,7 @@ void DSGXReset(struct DSGX* gx) {
 	gx->currentPoly.polyParams = 0x001F00C0;
 	gx->nextPoly.polyParams = 0x001F00C0;
 	gx->dmaSource = -1;
+	gx->renderer->reset(gx->renderer);
 }
 
 void DSGXAssociateRenderer(struct DSGX* gx, struct DSGXRenderer* renderer) {
diff --git a/src/ds/gx/software.c b/src/ds/gx/software.c
index 61377aa26..05e7f8903 100644
--- a/src/ds/gx/software.c
+++ b/src/ds/gx/software.c
@@ -440,6 +440,7 @@ static void DSGXSoftwareRendererReset(struct DSGXRenderer* renderer) {
 	struct DSGXSoftwareRenderer* softwareRenderer = (struct DSGXSoftwareRenderer*) renderer;
 	softwareRenderer->clearColor = 0;
 	softwareRenderer->clearStencil = 0;
+	softwareRenderer->clearDepth = 0xFFFFFF;
 }
 
 static void DSGXSoftwareRendererDeinit(struct DSGXRenderer* renderer) {
@@ -738,12 +739,13 @@ static void DSGXSoftwareRendererSetRAM(struct DSGXRenderer* renderer, struct DSG
 
 	color_t clearColor = softwareRenderer->clearColor;
 	uint16_t clearStencil = softwareRenderer->clearStencil;
+	uint32_t clearDepth = softwareRenderer->clearDepth;
 
 	for (i = 0; i < DS_VIDEO_VERTICAL_PIXELS * DS_VIDEO_HORIZONTAL_PIXELS ; i += 4) {
-		softwareRenderer->depthBuffer[i] = INT32_MAX;
-		softwareRenderer->depthBuffer[i + 1] = INT32_MAX;
-		softwareRenderer->depthBuffer[i + 2] = INT32_MAX;
-		softwareRenderer->depthBuffer[i + 3] = INT32_MAX;
+		softwareRenderer->depthBuffer[i] = clearDepth;
+		softwareRenderer->depthBuffer[i + 1] = clearDepth;
+		softwareRenderer->depthBuffer[i + 2] = clearDepth;
+		softwareRenderer->depthBuffer[i + 3] = clearDepth;
 		softwareRenderer->scanlineCache[i] = clearColor;
 		softwareRenderer->scanlineCache[i + 1] = clearColor;
 		softwareRenderer->scanlineCache[i + 2] = clearColor;
@@ -816,5 +818,8 @@ static void DSGXSoftwareRendererWriteRegister(struct DSGXRenderer* renderer, uin
 		softwareRenderer->clearColor |= (value & 0x001F) << 27;
 		softwareRenderer->clearStencil = (value & 0x3F00) >> 8;
 		break;
+	case DS9_REG_CLEAR_DEPTH:
+		softwareRenderer->clearDepth = (value & 0x7FFF) * 0x200 + 0x1FF;
+		break;
 	}
 }