implement depth uniforms

src/core/renderer_mtl/renderer_mtl.cpp

@@ -369,6 +369,16 @@ void RendererMTL::drawVertices(PICA::PrimType primType, std::span<const PICA::Ve
 		}
 	}
 
+	// Depth uniforms
+	struct {
+        float depthScale;
+       	float depthOffset;
+       	bool depthMapEnable;
+	} depthUniforms;
+	depthUniforms.depthScale = Floats::f24::fromRaw(regs[PICA::InternalRegs::DepthScale] & 0xffffff).toFloat32();
+   	depthUniforms.depthOffset = Floats::f24::fromRaw(regs[PICA::InternalRegs::DepthOffset] & 0xffffff).toFloat32();
+   	depthUniforms.depthMapEnable = regs[PICA::InternalRegs::DepthmapEnable] & 1;
+
 	// -------- Pipeline --------
 	Metal::PipelineHash pipelineHash{colorRenderTarget->format, DepthFmt::Unknown1};
 	if (depthStencilRenderTarget) {
@@ -436,6 +446,7 @@ void RendererMTL::drawVertices(PICA::PrimType primType, std::span<const PICA::Ve
 	bindTexturesToSlots(renderCommandEncoder);
 	renderCommandEncoder->setVertexBytes(&regs[0x48], (0x200 - 0x48) * sizeof(regs[0]), 0);
 	renderCommandEncoder->setFragmentBytes(&regs[0x48], (0x200 - 0x48) * sizeof(regs[0]), 0);
+	renderCommandEncoder->setVertexBytes(&depthUniforms, sizeof(depthUniforms), 2);
 	renderCommandEncoder->setFragmentBytes(&logicOp, sizeof(logicOp), 2);
 
 	renderCommandEncoder->drawPrimitives(toMTLPrimitiveType(primType), NS::UInteger(0), NS::UInteger(vertices.size()));

src/host_shaders/metal_shaders.metal

@@ -143,17 +143,31 @@ float decodeFP(uint hex, uint E, uint M) {
 	return as_type<float>(hex);
 }
 
-vertex DrawVertexOutWithClip vertexDraw(DrawVertexIn in [[stage_in]], constant PicaRegs& picaRegs [[buffer(0)]], constant VertTEV& tev [[buffer(1)]]) {
+struct DepthUniforms {
+    float depthScale;
+   	float depthOffset;
+   	bool depthMapEnable;
+};
+
+vertex DrawVertexOutWithClip vertexDraw(DrawVertexIn in [[stage_in]], constant PicaRegs& picaRegs [[buffer(0)]], constant VertTEV& tev [[buffer(1)]], constant DepthUniforms& depthUniforms [[buffer(2)]]) {
 	DrawVertexOut out;
 
 	// Position
 	out.position = in.position;
 	// Flip the y position
 	out.position.y = -out.position.y;
-	// in.position.z is in range of [-1 ... 1], convert it to [0 ... 1]
 	out.position.xyz /= out.position.w;
+
+	// Apply depth uniforms
+	out.position.z = out.position.z * depthUniforms.depthScale + depthUniforms.depthOffset;
+	// TODO: is this correct?
+	if (!depthUniforms.depthMapEnable) { // Divide z by w if depthmap enable == 0 (ie using W-buffering)
+		out.position.z /= out.position.w;
+	}
+
+	// in.position.z is in range of [-1, 1], convert it to [0, 1]
+	out.position.z = (out.position.z + 1.0) * 0.5;
 	out.position.w = 1.0;
-	out.position.z = (-out.position.z + 1.0) * 0.5;
 
 	// Color
 	out.color = min(abs(in.color), 1.0);
@@ -560,8 +574,6 @@ fragment float4 fragmentDraw(DrawVertexOut in [[stage_in]], float4 prevColor [[c
 		}
 	}
 
-	// TODO: depth
-
 	float4 color = performLogicOp(logicOp, globals.tevSources[15], prevColor);
 
 	// Perform alpha test