Reinterpret the data when binding a framebuffer with a different 16-bit format.

Car reflections in Outrun are better (see #11358) but have some
blue/yellow color garbage that will need a different fix.

GPU/Common/FramebufferManagerCommon.cpp

@@ -584,7 +584,7 @@ void FramebufferManagerCommon::ReformatFramebufferFrom(VirtualFramebuffer *vfb,
 	}
 
 	// Copy to a temp framebuffer.
-	Draw::Framebuffer *temp = GetTempFBO(TempFBO::COPY, vfb->renderWidth, vfb->renderHeight);
+	Draw::Framebuffer *temp = GetTempFBO(TempFBO::REINTERPRET, vfb->renderWidth, vfb->renderHeight);
 
 	draw_->CopyFramebufferImage(vfb->fbo, 0, 0, 0, 0, temp, 0, 0, 0, 0, vfb->renderWidth, vfb->renderHeight, 1, Draw::FBChannel::FB_COLOR_BIT, "reinterpret_prep");
 	draw_->BindFramebufferAsRenderTarget(vfb->fbo, { Draw::RPAction::DONT_CARE, Draw::RPAction::DONT_CARE, Draw::RPAction::DONT_CARE }, "reinterpret");

GPU/Common/FramebufferManagerCommon.h

@@ -158,6 +158,8 @@ enum class TempFBO {
 	BLIT,
 	// For copies of framebuffers (e.g. shader blending.)
 	COPY,
+	// For another type of framebuffers that can happen together with COPY (see Outrun)
+	REINTERPRET,
 	// Used to copy stencil data, means we need a stencil backing.
 	STENCIL,
 };
@@ -320,6 +322,7 @@ public:
 	const std::vector<VirtualFramebuffer *> &Framebuffers() {
 		return vfbs_;
 	}
+	void ReformatFramebufferFrom(VirtualFramebuffer *vfb, GEBufferFormat old);
 
 protected:
 	virtual void PackFramebufferSync_(VirtualFramebuffer *vfb, int x, int y, int w, int h);
@@ -344,7 +347,6 @@ protected:
 	void NotifyRenderFramebufferUpdated(VirtualFramebuffer *vfb, bool vfbFormatChanged);
 	void NotifyRenderFramebufferSwitched(VirtualFramebuffer *prevVfb, VirtualFramebuffer *vfb, bool isClearingDepth);
 
-	void ReformatFramebufferFrom(VirtualFramebuffer *vfb, GEBufferFormat old);
 	void BlitFramebufferDepth(VirtualFramebuffer *src, VirtualFramebuffer *dst);
 
 	void ResizeFramebufFBO(VirtualFramebuffer *vfb, int w, int h, bool force = false, bool skipCopy = false);

GPU/Common/TextureCacheCommon.cpp

@@ -486,9 +486,10 @@ TexCacheEntry *TextureCacheCommon::SetTexture() {
 				DeleteTexture(entryIter);
 			}
 
+			const AttachCandidate &candidate = candidates[index];
 			nextTexture_ = nullptr;
 			nextNeedsRebuild_ = false;
-			SetTextureFramebuffer(candidates[index]);
+			SetTextureFramebuffer(candidate);
 			return nullptr;
 		}
 	}
@@ -849,11 +850,19 @@ FramebufferMatchInfo TextureCacheCommon::MatchFramebuffer(
 			WARN_LOG_ONCE(diffStrides1, G3D, "Texturing from framebuffer with different strides %d != %d", entry.bufw, framebuffer->fb_stride);
 		}
 		// NOTE: This check is okay because the first texture formats are the same as the buffer formats.
-		if (entry.format != (GETextureFormat)framebuffer->format) {
-			WARN_LOG_ONCE(diffFormat1, G3D, "Texturing from framebuffer with different formats %s != %s", GeTextureFormatToString(entry.format), GeBufferFormatToString(framebuffer->format));
-			return FramebufferMatchInfo{ FramebufferMatch::NO_MATCH };
-		} else {
+		if (IsTextureFormatBufferCompatible(entry.format)) {
+			if (TextureFormatMatchesBufferFormat(entry.format, framebuffer->format)) {
 				return FramebufferMatchInfo{ FramebufferMatch::VALID };
+			} else if (IsTextureFormat16Bit(entry.format) && IsBufferFormat16Bit(framebuffer->format)) {
+				WARN_LOG_ONCE(diffFormat1, G3D, "Texturing from framebuffer with reinterpretable format: %s != %s", GeTextureFormatToString(entry.format), GeBufferFormatToString(framebuffer->format));
+				return FramebufferMatchInfo{ FramebufferMatch::VALID, 0, 0, true, TextureFormatToBufferFormat(entry.format) };
+			} else {
+				WARN_LOG_ONCE(diffFormat2, G3D, "Texturing from framebuffer with incompatible formats %s != %s", GeTextureFormatToString(entry.format), GeBufferFormatToString(framebuffer->format));
+				return FramebufferMatchInfo{ FramebufferMatch::NO_MATCH };
+			}
+		} else {
+			// Format incompatible, ignoring without comment. (maybe some really gnarly hacks will end up here...)
+			return FramebufferMatchInfo{ FramebufferMatch::NO_MATCH };
 		}
 	} else {
 		// Apply to buffered mode only.
@@ -944,6 +953,13 @@ void TextureCacheCommon::SetTextureFramebuffer(const AttachCandidate &candidate)
 	VirtualFramebuffer *framebuffer = candidate.fb;
 	FramebufferMatchInfo fbInfo = candidate.match;
 
+	if (candidate.match.reinterpret) {
+		// TODO: Kinda ugly, maybe switch direction of the call?
+		GEBufferFormat oldFormat = candidate.fb->format;
+		candidate.fb->format = candidate.match.reinterpretTo;
+		framebufferManager_->ReformatFramebufferFrom(candidate.fb, oldFormat);
+	}
+
 	_dbg_assert_msg_(framebuffer != nullptr, "Framebuffer must not be null.");
 
 	framebuffer->usageFlags |= FB_USAGE_TEXTURE;

GPU/Common/TextureCacheCommon.h

@@ -212,6 +212,8 @@ struct FramebufferMatchInfo {
 	FramebufferMatch match;
 	u32 xOffset;
 	u32 yOffset;
+	bool reinterpret;
+	GEBufferFormat reinterpretTo;
 };
 
 struct AttachCandidate {

GPU/ge_constants.h

@@ -419,12 +419,33 @@ enum GETextureFormat
 	GE_TFMT_DXT5 = 10,
 };
 
-const char *GeTextureFormatToString(GETextureFormat fmt);
-inline bool IsClutFormat(GETextureFormat fmt) {
-	return fmt == GE_TFMT_CLUT4 || fmt == GE_TFMT_CLUT8 || fmt == GE_TFMT_CLUT16 || fmt == GE_TFMT_CLUT32;
+const char *GeTextureFormatToString(GETextureFormat tfmt);
+inline bool IsClutFormat(GETextureFormat tfmt) {
+	return tfmt == GE_TFMT_CLUT4 || tfmt == GE_TFMT_CLUT8 || tfmt == GE_TFMT_CLUT16 || tfmt == GE_TFMT_CLUT32;
 }
-inline bool IsDXTFormat(GETextureFormat fmt) {
-	return fmt == GE_TFMT_DXT1 || fmt == GE_TFMT_DXT3 || fmt == GE_TFMT_DXT5;
+inline bool IsDXTFormat(GETextureFormat tfmt) {
+	return tfmt == GE_TFMT_DXT1 || tfmt == GE_TFMT_DXT3 || tfmt == GE_TFMT_DXT5;
+}
+inline bool IsTextureFormatBufferCompatible(GETextureFormat tfmt) {
+	return (int)tfmt < 4;
+}
+inline bool IsBufferFormat16Bit(GEBufferFormat bfmt) {
+	return (int)bfmt < 3;
+}
+inline bool IsTextureFormat16Bit(GETextureFormat tfmt) {
+	return (int)tfmt < 3;
+}
+inline bool TextureFormatMatchesBufferFormat(GETextureFormat fmt, GEBufferFormat bfmt) {
+	// First four matches perfectly.
+	if ((int)fmt < 4) {
+		return (int)fmt == (int)bfmt;
+	} else {
+		return false;
+	}
+}
+// only applicable if IsTextureFormatBufferCompatible(fmt)
+inline GEBufferFormat TextureFormatToBufferFormat(GETextureFormat bfmt) {
+	return (GEBufferFormat)(int)bfmt;
 }
 
 enum GETexLevelMode {