Add config option working around buggy graphics drivers

"subImageFix=true" should fix missing text on radeonsi fglrx
as well as most mobile drivers. Also fixes tileset atlas on
mobile.

mkxp.conf.sample

@@ -86,6 +86,15 @@
 # solidFonts=false
 
 
+# Work around buggy graphics drivers which don't
+# properly synchronize texture access, most
+# apparent when text doesn't show up or the map
+# tileset doesn't render at all
+# (default: disabled)
+#
+# subImageFix=false
+
+
 # Set the base path of the game to '/path/to/game'
 # (default: executable directory)
 #

src/bitmap.cpp

@@ -374,14 +374,46 @@ void Bitmap::stretchBlt(const IntRect &destRect,
 	if (opacity == 0)
 		return;
 
-	if (source.megaSurface())
+	SDL_Surface *srcSurf = source.megaSurface();
+
+	if (srcSurf && shState->config().subImageFix)
 	{
+		/* Blit from software surface, for broken GL drivers */
+		Vec2i gpTexSize;
+		shState->ensureTexSize(sourceRect.w, sourceRect.h, gpTexSize);
+		shState->bindTex();
+
+		GLMeta::subRectImageUpload(srcSurf->w, sourceRect.x, sourceRect.y, 0, 0,
+		                           sourceRect.w, sourceRect.h, srcSurf, GL_RGBA);
+		GLMeta::subRectImageEnd();
+
+		SimpleShader &shader = shState->shaders().simple;
+		shader.bind();
+		shader.setTranslation(Vec2i());
+		shader.setTexSize(gpTexSize);
+
+		p->pushSetViewport(shader);
+		p->bindFBO();
+
+		Quad &quad = shState->gpQuad();
+		quad.setTexRect(FloatRect(0, 0, sourceRect.w, sourceRect.h));
+		quad.setPosRect(destRect);
+
+		p->blitQuad(quad);
+		p->popViewport();
+
+		p->addTaintedArea(destRect);
+		p->onModified();
+
+		return;
+	}
+	else if (srcSurf)
+	{
+		/* Blit from software surface */
 		/* Don't do transparent blits for now */
 		if (opacity < 255)
 			source.ensureNonMega();
 
-		SDL_Surface *srcSurf = source.megaSurface();
-
 		SDL_Rect srcRect = sourceRect;
 		SDL_Rect dstRect = destRect;
 		SDL_Rect btmRect = { 0, 0, width(), height() };
@@ -405,18 +437,19 @@ void Bitmap::stretchBlt(const IntRect &destRect,
 
 		if (bltRect.w == dstRect.w && bltRect.h == dstRect.h)
 		{
+			/* Dest rectangle lies within bounding box */
 			TEX::uploadSubImage(destRect.x, destRect.y,
 			                    destRect.w, destRect.h,
 			                    blitTemp->pixels, GL_RGBA);
 		}
 		else
 		{
+			/* Clipped blit */
 			GLMeta::subRectImageUpload(blitTemp->w, bltRect.x - dstRect.x, bltRect.y - dstRect.y,
 			                           bltRect.x, bltRect.y, bltRect.w, bltRect.h, blitTemp, GL_RGBA);
 			GLMeta::subRectImageEnd();
 		}
 
-
 		SDL_FreeSurface(blitTemp);
 
 		p->onModified();
@@ -468,7 +501,6 @@ void Bitmap::stretchBlt(const IntRect &destRect,
 	}
 
 	p->addTaintedArea(destRect);
-
 	p->onModified();
 }
 
@@ -1023,7 +1055,7 @@ void Bitmap::drawText(const IntRect &rect, const char *str, int align)
 
 	if (fastBlit)
 	{
-		if (squeeze == 1.0)
+		if (squeeze == 1.0 && !shState->config().subImageFix)
 		{
 			/* Even faster: upload directly to bitmap texture.
 			 * We have to make sure the posRect lies within the texture

src/config.cpp

@@ -147,6 +147,7 @@ Config::Config()
       fixedFramerate(0),
       frameSkip(true),
       solidFonts(false),
+      subImageFix(false),
       gameFolder("."),
       anyAltToggleFS(false),
       enableReset(true),
@@ -174,6 +175,7 @@ void Config::read(int argc, char *argv[])
 	PO_DESC(fixedFramerate, int) \
 	PO_DESC(frameSkip, bool) \
 	PO_DESC(solidFonts, bool) \
+	PO_DESC(subImageFix, bool) \
 	PO_DESC(gameFolder, std::string) \
 	PO_DESC(anyAltToggleFS, bool) \
 	PO_DESC(enableReset, bool) \

src/config.h

@@ -45,6 +45,8 @@ struct Config
 
 	bool solidFonts;
 
+	bool subImageFix;
+
 	std::string gameFolder;
 	bool anyAltToggleFS;
 	bool enableReset;

src/tilemap.cpp

@@ -26,6 +26,7 @@
 #include "table.h"
 
 #include "sharedstate.h"
+#include "config.h"
 #include "glstate.h"
 #include "gl-util.h"
 #include "gl-meta.h"
@@ -542,10 +543,48 @@ struct TilemapPrivate
 		if (tileset->megaSurface())
 		{
 			/* Mega surface tileset */
-			TEX::bind(atlas.gl.tex);
-
 			SDL_Surface *tsSurf = tileset->megaSurface();
 
+			if (shState->config().subImageFix)
+			{
+				/* Implementation for broken GL drivers */
+				FBO::bind(atlas.gl.fbo);
+				glState.blend.pushSet(false);
+				glState.viewport.pushSet(IntRect(0, 0, atlas.size.x, atlas.size.y));
+
+				SimpleShader &shader = shState->shaders().simple;
+				shader.bind();
+				shader.applyViewportProj();
+				shader.setTranslation(Vec2i());
+
+				Quad &quad = shState->gpQuad();
+
+				for (size_t i = 0; i < blits.size(); ++i)
+				{
+					const TileAtlas::Blit &blitOp = blits[i];
+
+					Vec2i texSize;
+					shState->ensureTexSize(tsLaneW, blitOp.h, texSize);
+					shState->bindTex();
+					GLMeta::subRectImageUpload(tsSurf->w, blitOp.src.x, blitOp.src.y,
+					                           0, 0, tsLaneW, blitOp.h, tsSurf, GL_RGBA);
+
+					shader.setTexSize(texSize);
+					quad.setTexRect(FloatRect(0, 0, tsLaneW, blitOp.h));
+					quad.setPosRect(FloatRect(blitOp.dst.x, blitOp.dst.y, tsLaneW, blitOp.h));
+
+					quad.draw();
+				}
+
+				GLMeta::subRectImageEnd();
+				glState.viewport.pop();
+				glState.blend.pop();
+			}
+			else
+			{
+				/* Clean implementation */
+				TEX::bind(atlas.gl.tex);
+
 				for (size_t i = 0; i < blits.size(); ++i)
 				{
 					const TileAtlas::Blit &blitOp = blits[i];
@@ -556,6 +595,8 @@ struct TilemapPrivate
 
 				GLMeta::subRectImageEnd();
 			}
+
+		}
 		else
 		{
 			/* Regular tileset */