diff --git a/src/O3DGlideRenderer.m b/src/O3DGlideRenderer.m
index f3a2e34..f917b7d 100644
--- a/src/O3DGlideRenderer.m
+++ b/src/O3DGlideRenderer.m
@@ -171,10 +171,13 @@ grGlideShutdownCdecl(void)
 #endif
 
 		if (!grSstWinOpen(hWnd, sizeToScreenResolution(resolution),
-		    floatToScreenRefresh(refreshRate), GR_COLORFORMAT_RGBA,
+		    floatToScreenRefresh(refreshRate), GR_COLORFORMAT_ARGB,
 		    GR_ORIGIN_LOWER_LEFT, 2, 1))
 			@throw [OFInitializationFailedException
 			    exceptionWithClass: self.class];
+
+		grDepthBufferMode(GR_DEPTHBUFFER_WBUFFER);
+		grDepthMask(FXTRUE);
 	} @catch (id e) {
 		[self release];
 		@throw e;
@@ -196,7 +199,7 @@ grGlideShutdownCdecl(void)
 
 - (void)beginFrame
 {
-	grBufferClear(0, 0, 0);
+	grBufferClear(0, 0, GR_WDEPTHVALUE_FARTHEST);
 }
 
 - (void)drawPolygonWithVertices: (const O3DVertex *)vertices
@@ -216,10 +219,10 @@ grGlideShutdownCdecl(void)
 			    (vertices[i].position.x + 1) * halfWidth;
 			glideVertices[i].y =
 			    (vertices[i].position.y + 1) * halfHeight;
+			glideVertices[i].oow = 1.f / vertices[i].position.z;
 			glideVertices[i].r = vertices[i].color.r * 255;
 			glideVertices[i].g = vertices[i].color.g * 255;
 			glideVertices[i].b = vertices[i].color.b * 255;
-			glideVertices[i].a = vertices[i].color.a * 255;
 		}
 
 		grDrawPolygonVertexList((int)count, glideVertices);
diff --git a/src/O3DRenderer.h b/src/O3DRenderer.h
index 99ea0ac..48ab208 100644
--- a/src/O3DRenderer.h
+++ b/src/O3DRenderer.h
@@ -19,10 +19,10 @@ OF_ASSUME_NONNULL_BEGIN
 
 typedef struct OF_BOXABLE {
 	struct {
-		float x, y;
+		float x, y, z;
 	} position;
 	struct {
-		float r, g, b, a;
+		float r, g, b;
 	} color;
 } O3DVertex;
 
diff --git a/tests/TestsAppDelegate.m b/tests/TestsAppDelegate.m
index b42c770..af40031 100644
--- a/tests/TestsAppDelegate.m
+++ b/tests/TestsAppDelegate.m
@@ -32,21 +32,21 @@ OF_APPLICATION_DELEGATE(TestsAppDelegate)
 		       options: nil] autorelease];
 
 	const O3DVertex outerTriangle[] = {
-		{{ -1, -1 }, { 1, 0, 0 }},
-		{{ 0, 1 }, { 0, 1, 0 }},
-		{{ 1, -1 }, { 0, 0, 1 }}
+		{{ -1, -1, 1 }, { 1, 0, 0 }},
+		{{ 0, 1, 1 }, { 0, 1, 0 }},
+		{{ 1, -1, 1 }, { 0, 0, 1 }}
 	};
 	const O3DVertex innerTriangle[] = {
-		{{ -0.5, 0.5 }, { 1, 1, 0 }},
-		{{ 0, -0.5 }, { 0, 1, 1 }},
-		{{ 0.5, 0.5 }, { 1, 0, 1 }}
+		{{ -0.5, 0.5, 0 }, { 1, 1, 0 }},
+		{{ 0, -0.5, 0 }, { 0, 1, 1 }},
+		{{ 0.5, 0.5, 0 }, { 1, 0, 1 }}
 	};
 
 	OFDate *startDate = [OFDate date];
 	while (-startDate.timeIntervalSinceNow < 5) {
 		[renderer beginFrame];
-		[renderer drawPolygonWithVertices: outerTriangle count: 3];
 		[renderer drawPolygonWithVertices: innerTriangle count: 3];
+		[renderer drawPolygonWithVertices: outerTriangle count: 3];
 		[renderer endFrame];
 	}