BLADERUNNER: Fixed alpha channel issues

Alpha channel is inverted in the game assets and that lead to issues in
OpenGL renderer. E.g. screenshot of savegames were partly black or
showing artifacts

closes #10983

4 files changed, 13 insertions, 6 deletions

diff --git a/engines/bladerunner/bladerunner.cpp b/engines/bladerunner/bladerunner.cpp
index e3e54299fb..9621612ac6 100644
--- a/engines/bladerunner/bladerunner.cpp
+++ b/engines/bladerunner/bladerunner.cpp
@@ -2163,14 +2163,18 @@ void BladeRunnerEngine::blitToScreen(const Graphics::Surface &src) const {
 
 Graphics::Surface BladeRunnerEngine::generateThumbnail() const {
 	Graphics::Surface thumbnail;
-	thumbnail.create(640 / 8, 480 / 8, _surfaceFront.format);
+	thumbnail.create(640 / 8, 480 / 8, gameDataPixelFormat());
 
 	for (int y = 0; y < thumbnail.h; ++y) {
 		for (int x = 0; x < thumbnail.w; ++x) {
-			uint16       *dstPixel = (uint16 *)thumbnail.getBasePtr(x, y);
-			const uint16 *srcPixel = (const uint16 *)_surfaceFront.getBasePtr(x * 8, y * 8);
+			uint8 r, g, b;
 
-			*dstPixel = *srcPixel;
+			uint16  srcPixel = *(uint16 *)_surfaceFront.getBasePtr(x * 8, y * 8);
+			uint16 *dstPixel = (uint16 *)thumbnail.getBasePtr(x, y);
+
+			// Throw away alpha channel as it is not needed
+			_surfaceFront.format.colorToRGB(srcPixel, r, g, b);
+			*dstPixel = thumbnail.format.RGBToColor(r, g, b);
 		}
 	}
 
diff --git a/engines/bladerunner/font.cpp b/engines/bladerunner/font.cpp
index c10c12db81..703495cd79 100644
--- a/engines/bladerunner/font.cpp
+++ b/engines/bladerunner/font.cpp
@@ -199,6 +199,7 @@ void Font::drawCharacter(const uint8 character, Graphics::Surface &surface, int
 			gameDataPixelFormat().colorToARGB(*srcPtr, a, r, g, b);
 			if (!a) {
 				if (_color == _defaultColor) {
+					// Ignore the alpha in the output as it is inversed in the input
 					*dstPtr = surface.format.RGBToColor(r, g, b);
 				} else {
 					*dstPtr = _color;
diff --git a/engines/bladerunner/shape.cpp b/engines/bladerunner/shape.cpp
index 39a7758a0f..2d01d1336a 100644
--- a/engines/bladerunner/shape.cpp
+++ b/engines/bladerunner/shape.cpp
@@ -112,7 +112,8 @@ void Shape::draw(Graphics::Surface &surface, int x, int y) const {
 
 			uint8 a, r, g, b;
 			gameDataPixelFormat().colorToARGB(shpColor, a, r, g, b);
-			uint16 outColor = (uint16)surface.format.ARGBToColor(a, r, g, b);
+			// Ignore the alpha in the output as it is inversed in the input
+			uint16 outColor = (uint16)surface.format.RGBToColor(r, g, b);
 
 			if (!a) {
 				*(uint16 *)(surface.getBasePtr(dst_x + xi, dst_y + yi)) = outColor;
diff --git a/engines/bladerunner/vqa_decoder.cpp b/engines/bladerunner/vqa_decoder.cpp
index 3b230ef6c6..68737858ca 100644
--- a/engines/bladerunner/vqa_decoder.cpp
+++ b/engines/bladerunner/vqa_decoder.cpp
@@ -835,7 +835,8 @@ void VQADecoder::VQAVideoTrack::VPTRWriteBlock(Graphics::Surface *surface, unsig
 
 				uint8 a, r, g, b;
 				gameDataPixelFormat().colorToARGB(vqaColor, a, r, g, b);
-				uint16 outColor = (uint16)surface->format.ARGBToColor(a, r, g, b);
+				// Ignore the alpha in the output as it is inversed in the input
+				uint16 outColor = (uint16)surface->format.RGBToColor(r, g, b);
 
 				if (!(alpha && a)) {
 					*(uint16 *)(surface->getBasePtr(dst_x + x, dst_y + y)) = outColor;