GS/HW: Allow conversion from 32bit to 24bit depth

bin/resources/shaders/dx11/convert.fx

@@ -237,6 +237,13 @@ float rgb5a1_to_depth16(float4 val)
 	return float(((c.r & 0xF8u) >> 3) | ((c.g & 0xF8u) << 2) | ((c.b & 0xF8u) << 7) | ((c.a & 0x80u) << 8)) * exp2(-32.0f);
 }
 
+float ps_convert_float32_float24(PS_INPUT input) : SV_Depth
+{
+	// Truncates depth value to 24bits
+	uint d = uint(sample_c(input.t).r * exp2(32.0f)) & 0xFFFFFF;
+	return float(d) * exp2(-32.0f);
+}
+
 float ps_convert_rgba8_float32(PS_INPUT input) : SV_Depth
 {
 	// Convert an RGBA texture into a float depth texture

bin/resources/shaders/opengl/convert.glsl

@@ -144,6 +144,15 @@ float rgb5a1_to_depth16(vec4 unorm)
 	return float(((c.r & 0xF8u) >> 3) | ((c.g & 0xF8u) << 2) | ((c.b & 0xF8u) << 7) | ((c.a & 0x80u) << 8)) * exp2(-32.0f);
 }
 
+#ifdef ps_convert_float32_float24
+void ps_convert_float32_float24()
+{
+	// Truncates depth value to 24bits
+	uint d = uint(sample_c().r * exp2(32.0f)) & 0xFFFFFF;
+	gl_FragDepth = float(d) * exp2(-32.0f);
+}
+#endif
+
 #ifdef ps_convert_rgba8_float32
 void ps_convert_rgba8_float32()
 {

bin/resources/shaders/vulkan/convert.glsl

@@ -214,6 +214,15 @@ float rgb5a1_to_depth16(vec4 unorm)
 	return float(((c.r & 0xF8u) >> 3) | ((c.g & 0xF8u) << 2) | ((c.b & 0xF8u) << 7) | ((c.a & 0x80u) << 8)) * exp2(-32.0f);
 }
 
+#ifdef ps_convert_float32_float24
+void ps_convert_float32_float24()
+{
+	// Truncates depth value to 24bits
+	uint d = uint(sample_c(v_tex).r * exp2(32.0f)) & 0xFFFFFF;
+	gl_FragDepth = float(d) * exp2(-32.0f);
+}
+#endif
+
 #ifdef ps_convert_rgba8_float32
 void ps_convert_rgba8_float32()
 {

pcsx2/GS/Renderers/Common/GSDevice.cpp

@@ -64,6 +64,7 @@ const char* shaderName(ShaderConvert value)
 		case ShaderConvert::RGBA8_TO_FLOAT24_BILN:  return "ps_convert_rgba8_float24_biln";
 		case ShaderConvert::RGBA8_TO_FLOAT16_BILN:  return "ps_convert_rgba8_float16_biln";
 		case ShaderConvert::RGB5A1_TO_FLOAT16_BILN: return "ps_convert_rgb5a1_float16_biln";
+		case ShaderConvert::FLOAT32_TO_FLOAT24:     return "ps_convert_float32_float24";
 		case ShaderConvert::DEPTH_COPY:             return "ps_depth_copy";
 		case ShaderConvert::DOWNSAMPLE_COPY:        return "ps_downsample_copy";
 		case ShaderConvert::RGBA_TO_8I:             return "ps_convert_rgba_8i";

pcsx2/GS/Renderers/Common/GSDevice.h

@@ -39,6 +39,7 @@ enum class ShaderConvert
 	RGBA8_TO_FLOAT24_BILN,
 	RGBA8_TO_FLOAT16_BILN,
 	RGB5A1_TO_FLOAT16_BILN,
+	FLOAT32_TO_FLOAT24,
 	DEPTH_COPY,
 	DOWNSAMPLE_COPY,
 	RGBA_TO_8I,
@@ -78,6 +79,7 @@ static inline bool HasDepthOutput(ShaderConvert shader)
 		case ShaderConvert::RGBA8_TO_FLOAT24_BILN:
 		case ShaderConvert::RGBA8_TO_FLOAT16_BILN:
 		case ShaderConvert::RGB5A1_TO_FLOAT16_BILN:
+		case ShaderConvert::FLOAT32_TO_FLOAT24:
 		case ShaderConvert::DEPTH_COPY:
 			return true;
 		default:

pcsx2/GS/Renderers/HW/GSTextureCache.cpp

@@ -2026,6 +2026,20 @@ GSTextureCache::Target* GSTextureCache::LookupTarget(GIFRegTEX0 TEX0, const GSVe
 		else if (dst->m_scale != scale)
 			scale = dst->m_scale;
 
+		// Game is changing from 32bit deptth to 24bit, meaning any top values in the depth will no longer be valid, I hope no games rely on these values being maintained, else we're screwed.
+		if (type == DepthStencil && dst->m_type == DepthStencil && GSLocalMemory::m_psm[dst->m_TEX0.PSM].trbpp == 32 && GSLocalMemory::m_psm[TEX0.PSM].trbpp == 24 && dst->m_alpha_max > 0)
+		{
+			calcRescale(dst);
+			GSTexture* tex = g_gs_device->CreateDepthStencil(new_scaled_size.x, new_scaled_size.y, GSTexture::Format::DepthStencil, false);
+			g_gs_device->StretchRect(dst->m_texture, sRect, tex, dRect, ShaderConvert::FLOAT32_TO_FLOAT24, false);
+			g_perfmon.Put(GSPerfMon::TextureCopies, 1);
+			g_gs_device->Recycle(dst->m_texture);
+
+			dst->m_texture = tex;
+			dst->m_alpha_min = 0;
+			dst->m_alpha_max = 0;
+		}
+
 		// If our RGB was invalidated, we need to pull it from depth.
 		// Terminator 3 will reuse our dst_matched target with the RGB masked, then later use the full ARGB area, so we need to update the depth.
 		const bool preserve_target = preserve_rgb || preserve_alpha;

pcsx2/GS/Renderers/Metal/convert.metal

@@ -249,6 +249,13 @@ struct ConvertToDepthRes
 	}
 };
 
+fragment DepthOut ps_convert_float32_float24(ConvertShaderData data [[stage_in]], ConvertPSDepthRes res)
+{
+	// Truncates depth value to 24bits
+	uint val = uint(res.sample(data.t) * 0x1p32) & 0xFFFFFF;
+	return float(val) * 0x1p-32f;
+}
+
 fragment DepthOut ps_convert_rgba8_float32(ConvertShaderData data [[stage_in]], ConvertToDepthRes res)
 {
 	return rgba8_to_depth32(res.sample(data.t));