Implement smooth depal lookups for Test Drive's strange usage.

GPU/Common/DepalettizeShaderCommon.cpp

@@ -45,7 +45,7 @@ static const VaryingDef varyings[1] = {
 };
 
 // Uses integer instructions available since OpenGL 3.0, ES 3.0 (and 2.0 with extensions), and of course Vulkan and D3D11.
-void GenerateDepalShader300(ShaderWriter &writer, const DepalConfig &config, const ShaderLanguageDesc &lang) {
+void GenerateDepalShader300(ShaderWriter &writer, const DepalConfig &config) {
 	const int shift = config.shift;
 	const int mask = config.mask;
 
@@ -140,7 +140,7 @@ void GenerateDepalShader300(ShaderWriter &writer, const DepalConfig &config, con
 }
 
 // FP only, to suit GL(ES) 2.0 and DX9
-void GenerateDepalShaderFloat(ShaderWriter &writer, const DepalConfig &config, const ShaderLanguageDesc &lang) {
+void GenerateDepalShaderFloat(ShaderWriter &writer, const DepalConfig &config) {
 	char lookupMethod[128] = "index.r";
 
 	const int shift = config.shift;
@@ -288,23 +288,64 @@ void GenerateDepalShaderFloat(ShaderWriter &writer, const DepalConfig &config, c
 	writer.C("  vec4 outColor = ").SampleTexture2D("pal", "vec2(coord, 0.0)").C(";\n");
 }
 
+void GenerateDepalSmoothed(ShaderWriter &writer, const DepalConfig &config) {
+	const char *sourceChannel = "error";
+	float indexMultiplier = 32.0f;
+
+	if (config.bufferFormat == GE_FORMAT_5551) {
+		_dbg_assert_(config.mask == 0x1F);
+		switch (config.shift) {
+		case 0: sourceChannel = "r"; break;
+		case 5: sourceChannel = "g"; break;
+		case 10: sourceChannel = "b"; break;
+		default: _dbg_assert_(false);
+		}
+	} else if (config.bufferFormat == GE_FORMAT_565) {
+		_dbg_assert_(config.mask == 0x1F || config.mask == 0x3F);
+		switch (config.shift) {
+		case 0: sourceChannel = "r"; break;
+		case 5: sourceChannel = "g"; indexMultiplier = 64.0f; break;
+		case 11: sourceChannel = "b"; break;
+		default: _dbg_assert_(false);
+		}
+	} else {
+		_dbg_assert_(false);
+	}
+
+	writer.C("  float index = ").SampleTexture2D("tex", "v_texcoord").F(".%s * %0.1f;\n", sourceChannel, indexMultiplier);
+
+	float texturePixels = 256.f;
+	if (config.clutFormat != GE_CMODE_32BIT_ABGR8888) {
+		texturePixels = 512.f;
+	}
+
+	writer.F("  float coord = (index + 0.5) * %f;\n", 1.0 / texturePixels);
+	writer.C("  vec4 outColor = ").SampleTexture2D("pal", "vec2(coord, 0.0)").C(";\n");
+}
+
 void GenerateDepalFs(char *buffer, const DepalConfig &config, const ShaderLanguageDesc &lang) {
 	ShaderWriter writer(buffer, lang, ShaderStage::Fragment);
 	writer.DeclareSamplers(samplers);
 	writer.HighPrecisionFloat();
 	writer.BeginFSMain(Slice<UniformDef>::empty(), varyings, FSFLAG_NONE);
-	switch (lang.shaderLanguage) {
-	case HLSL_D3D9:
-	case GLSL_1xx:
-		GenerateDepalShaderFloat(writer, config, lang);
-		break;
-	case GLSL_VULKAN:
-	case GLSL_3xx:
-	case HLSL_D3D11:
-		GenerateDepalShader300(writer, config, lang);
-		break;
-	default:
-		_assert_msg_(false, "Depal shader language not supported: %d", (int)lang.shaderLanguage);
+	if (config.smoothedDepal) {
+		// Handles a limited set of cases, but doesn't need any integer math so we don't
+		// need two variants.
+		GenerateDepalSmoothed(writer, config);
+	} else {
+		switch (lang.shaderLanguage) {
+		case HLSL_D3D9:
+		case GLSL_1xx:
+			GenerateDepalShaderFloat(writer, config);
+			break;
+		case GLSL_VULKAN:
+		case GLSL_3xx:
+		case HLSL_D3D11:
+			GenerateDepalShader300(writer, config);
+			break;
+		default:
+			_assert_msg_(false, "Depal shader language not supported: %d", (int)lang.shaderLanguage);
+		}
 	}
 	writer.EndFSMain("outColor", FSFLAG_NONE);
 }

GPU/Common/DepalettizeShaderCommon.h

@@ -31,6 +31,7 @@ struct DepalConfig {
 	GEPaletteFormat clutFormat;
 	GETextureFormat textureFormat;
 	GEBufferFormat bufferFormat;
+	bool smoothedDepal;
 };
 
 void GenerateDepalFs(char *buffer, const DepalConfig &config, const ShaderLanguageDesc &lang);

GPU/Common/FragmentShaderGenerator.cpp

@@ -23,8 +23,10 @@
 #include "Common/GPU/OpenGL/GLFeatures.h"
 #include "Common/GPU/ShaderWriter.h"
 #include "Common/GPU/thin3d.h"
+#include "Core/Compatibility.h"
 #include "Core/Reporting.h"
 #include "Core/Config.h"
+#include "Core/System.h"
 #include "GPU/Common/GPUStateUtils.h"
 #include "GPU/Common/ShaderId.h"
 #include "GPU/Common/ShaderUniforms.h"
@@ -88,6 +90,7 @@ bool GenerateFragmentShader(const FShaderID &id, char *buffer, const ShaderLangu
 
 	bool doFlatShading = id.Bit(FS_BIT_FLATSHADE) && !flatBug;
 	bool shaderDepal = id.Bit(FS_BIT_SHADER_DEPAL) && !texture3D;  // combination with texture3D not supported. Enforced elsewhere too.
+	bool smoothedDepal = id.Bit(FS_BIT_SHADER_SMOOTHED_DEPAL);
 	bool bgraTexture = id.Bit(FS_BIT_BGRA_TEXTURE);
 	bool colorWriteMask = id.Bit(FS_BIT_COLOR_WRITEMASK) && compat.bitwiseOps;
 
@@ -590,6 +593,31 @@ bool GenerateFragmentShader(const FShaderID &id, char *buffer, const ShaderLangu
 						}
 					}
 				}
+			} else if (shaderDepal && smoothedDepal) {
+				// Specific mode for Test Drive. Fixes the banding.
+				if (doTextureProjection) {
+					// We don't use textureProj because we need better control and it's probably not much of a savings anyway.
+					// However it is good for precision on older hardware like PowerVR.
+					WRITE(p, "  vec2 uv = %s.xy/%s.z;\n  vec2 uv_round;\n", texcoord, texcoord);
+				} else {
+					WRITE(p, "  vec2 uv = %s.xy;\n  vec2 uv_round;\n", texcoord);
+				}
+				// Restrictions on this are checked before setting the smoothed flag.
+				// Only RGB565 and RGBA5551 are supported, and only the specific shifts hitting the
+				// channels directly.
+				WRITE(p, "  vec4 t = %s(tex, %s.xy);\n", compat.texture, texcoord);
+				WRITE(p, "  uint depalShift = (u_depal_mask_shift_off_fmt >> 8) & 0xFFU;\n");
+				WRITE(p, "  uint depalFmt = (u_depal_mask_shift_off_fmt >> 24) & 0x3U;\n");
+				WRITE(p, "  float index0 = t.r;\n");
+				WRITE(p, "  float mul = 32.0 / 256.0;\n");
+				WRITE(p, "  if (depalFmt == 0) {\n");  // yes, different versions of Test Drive use different formats. Could do compile time by adding more compat flags but meh.
+				WRITE(p, "    if (depalShift == 5) { index0 = t.g; mul = 64.0 / 256.0; }\n");
+				WRITE(p, "    else if (depalShift == 11) { index0 = t.b; }\n");
+				WRITE(p, "  } else {\n");
+				WRITE(p, "    if (depalShift == 5) { index0 = t.g; }\n");
+				WRITE(p, "    else if (depalShift == 10) { index0 = t.b; }\n");
+				WRITE(p, "  }\n");
+				WRITE(p, "  t = %s(pal, vec2(index0 * mul, 0.0));\n", compat.texture);
 			} else {
 				if (doTextureProjection) {
 					// We don't use textureProj because we need better control and it's probably not much of a savings anyway.

GPU/Common/ShaderId.cpp

@@ -261,6 +261,7 @@ void ComputeFragmentShaderID(FShaderID *id_out, const Draw::Bugs &bugs) {
 		bool doTextureAlpha = gstate.isTextureAlphaUsed();
 		bool doFlatShading = gstate.getShadeMode() == GE_SHADE_FLAT;
 		bool useShaderDepal = gstate_c.useShaderDepal;
+		bool useSmoothedDepal = gstate_c.useSmoothedShaderDepal;
 		bool colorWriteMask = IsColorWriteMaskComplex(gstate_c.allowFramebufferRead);
 
 		// Note how we here recompute some of the work already done in state mapping.
@@ -290,6 +291,7 @@ void ComputeFragmentShaderID(FShaderID *id_out, const Draw::Bugs &bugs) {
 			}
 			id.SetBit(FS_BIT_BGRA_TEXTURE, gstate_c.bgraTexture);
 			id.SetBit(FS_BIT_SHADER_DEPAL, useShaderDepal);
+			id.SetBit(FS_BIT_SHADER_SMOOTHED_DEPAL, useSmoothedDepal);
 			id.SetBit(FS_BIT_3D_TEXTURE, gstate_c.curTextureIs3D);
 		}
 

GPU/Common/ShaderId.h

@@ -94,6 +94,7 @@ enum FShaderBit : uint8_t {
 	FS_BIT_NO_DEPTH_CANNOT_DISCARD_STENCIL = 49,
 	FS_BIT_COLOR_WRITEMASK = 50,
 	FS_BIT_3D_TEXTURE = 51,
+	FS_BIT_SHADER_SMOOTHED_DEPAL = 52,
 };
 
 static inline FShaderBit operator +(FShaderBit bit, int i) {

GPU/Common/TextureCacheCommon.cpp

@@ -1859,6 +1859,31 @@ bool CanDepalettize(GETextureFormat texFormat, GEBufferFormat bufferFormat) {
 	}
 }
 
+// If the palette is detected as a smooth ramp, we can interpolate for higher color precision.
+// But we only do it if the mask/shift exactly matches a color channel, else something different might be going
+// on and we definitely don't want to interpolate.
+// Great enhancement for Test Drive.
+static bool CanUseSmoothDepal(const GPUgstate &gstate, GEBufferFormat framebufferFormat, int rampLength) {
+	if (gstate.getClutIndexStartPos() == 0 &&
+		gstate.getClutIndexMask() <= rampLength) {
+		switch (framebufferFormat) {
+		case GE_FORMAT_565:
+			if (gstate.getClutIndexShift() == 0 || gstate.getClutIndexShift() == 11) {
+				return gstate.getClutIndexMask() == 0x1F;
+			} else if (gstate.getClutIndexShift() == 5) {
+				return gstate.getClutIndexMask() == 0x3F;
+			}
+			break;
+		case GE_FORMAT_5551:
+			if (gstate.getClutIndexShift() == 0 || gstate.getClutIndexShift() == 5 || gstate.getClutIndexShift() == 10) {
+				return gstate.getClutIndexMask() == 0x1F;
+			}
+			break;
+		}
+	}
+	return false;
+}
+
 void TextureCacheCommon::ApplyTextureFramebuffer(VirtualFramebuffer *framebuffer, GETextureFormat texFormat, RasterChannel channel) {
 	TextureShader *textureShader = nullptr;
 	uint32_t clutMode = gstate.clutformat & 0xFFFFFF;
@@ -1881,13 +1906,18 @@ void TextureCacheCommon::ApplyTextureFramebuffer(VirtualFramebuffer *framebuffer
 		break;
 	}
 
+	const GEPaletteFormat clutFormat = gstate.getClutPaletteFormat();
+	ClutTexture clutTexture{};
+	bool smoothedDepal = false;
+
 	if (need_depalettize && !g_Config.bDisableSlowFramebufEffects) {
+		clutTexture = textureShaderCache_->GetClutTexture(clutFormat, clutHash_, clutBufRaw_);
+		smoothedDepal = CanUseSmoothDepal(gstate, framebuffer->drawnFormat, clutTexture.rampLength);
+
 		if (useShaderDepal) {
-			const GEPaletteFormat clutFormat = gstate.getClutPaletteFormat();
 
 			// Very icky conflation here of native and thin3d rendering. This will need careful work per backend in BindAsClutTexture.
-			Draw::Texture *clutTexture = textureShaderCache_->GetClutTexture(clutFormat, clutHash_, clutBufRaw_);
-			BindAsClutTexture(clutTexture);
+			BindAsClutTexture(clutTexture.texture);
 
 			framebufferManager_->BindFramebufferAsColorTexture(0, framebuffer, BINDFBCOLOR_MAY_COPY_WITH_UV | BINDFBCOLOR_APPLY_TEX_OFFSET);
 			// Vulkan needs to do some extra work here to pick out the native handle from Draw.
@@ -1901,7 +1931,8 @@ void TextureCacheCommon::ApplyTextureFramebuffer(VirtualFramebuffer *framebuffer
 
 			// Since we started/ended render passes, might need these.
 			gstate_c.Dirty(DIRTY_DEPAL);
-			gstate_c.SetUseShaderDepal(true);
+
+			gstate_c.SetUseShaderDepal(true, smoothedDepal);
 			gstate_c.depalFramebufferFormat = framebuffer->drawnFormat;
 			const u32 bytesPerColor = clutFormat == GE_CMODE_32BIT_ABGR8888 ? sizeof(u32) : sizeof(u16);
 			const u32 clutTotalColors = clutMaxBytes_ / bytesPerColor;
@@ -1913,13 +1944,13 @@ void TextureCacheCommon::ApplyTextureFramebuffer(VirtualFramebuffer *framebuffer
 			return;
 		}
 
-		textureShader = textureShaderCache_->GetDepalettizeShader(clutMode, texFormat, depth ? GE_FORMAT_DEPTH16 : framebuffer->drawnFormat);
-		gstate_c.SetUseShaderDepal(false);
+		textureShader = textureShaderCache_->GetDepalettizeShader(clutMode, texFormat, depth ? GE_FORMAT_DEPTH16 : framebuffer->drawnFormat, smoothedDepal);
+		gstate_c.SetUseShaderDepal(false, false);
 	}
 
 	if (textureShader) {
 		const GEPaletteFormat clutFormat = gstate.getClutPaletteFormat();
-		Draw::Texture *clutTexture = textureShaderCache_->GetClutTexture(clutFormat, clutHash_, clutBufRaw_);
+		ClutTexture clutTexture = textureShaderCache_->GetClutTexture(clutFormat, clutHash_, clutBufRaw_);
 		Draw::Framebuffer *depalFBO = framebufferManager_->GetTempFBO(TempFBO::DEPAL, framebuffer->renderWidth, framebuffer->renderHeight);
 		draw_->BindTexture(0, nullptr);
 		draw_->BindTexture(1, nullptr);
@@ -1930,10 +1961,11 @@ void TextureCacheCommon::ApplyTextureFramebuffer(VirtualFramebuffer *framebuffer
 		draw_->SetViewports(1, &vp);
 
 		draw_->BindFramebufferAsTexture(framebuffer->fbo, 0, depth ? Draw::FB_DEPTH_BIT : Draw::FB_COLOR_BIT, 0);
-		draw_->BindTexture(1, clutTexture);
-		Draw::SamplerState *nearest = textureShaderCache_->GetSampler();
+		draw_->BindTexture(1, clutTexture.texture);
+		Draw::SamplerState *nearest = textureShaderCache_->GetSampler(false);
+		Draw::SamplerState *clutSampler = textureShaderCache_->GetSampler(smoothedDepal);
 		draw_->BindSamplerStates(0, 1, &nearest);
-		draw_->BindSamplerStates(1, 1, &nearest);
+		draw_->BindSamplerStates(1, 1, &clutSampler);
 
 		textureShaderCache_->ApplyShader(textureShader,
 			framebuffer->bufferWidth, framebuffer->bufferHeight, framebuffer->renderWidth, framebuffer->renderHeight,
@@ -1958,7 +1990,7 @@ void TextureCacheCommon::ApplyTextureFramebuffer(VirtualFramebuffer *framebuffer
 		framebufferManager_->BindFramebufferAsColorTexture(0, framebuffer, BINDFBCOLOR_MAY_COPY_WITH_UV | BINDFBCOLOR_APPLY_TEX_OFFSET);
 		BoundFramebufferTexture();
 
-		gstate_c.SetUseShaderDepal(false);
+		gstate_c.SetUseShaderDepal(false, false);
 		gstate_c.SetTextureFullAlpha(gstate.getTextureFormat() == GE_TFMT_5650);
 	}