Fix for alpha blending using gl fixed-functions not matching shader implementation

3 files changed, 41 insertions, 3 deletions

diff --git a/indra/llappearance/lltexlayer.cpp b/indra/llappearance/lltexlayer.cpp
index d1edd4f095..6e184beac8 100644
--- a/indra/llappearance/lltexlayer.cpp
+++ b/indra/llappearance/lltexlayer.cpp
@@ -150,6 +150,10 @@ BOOL LLTexLayerSetBuffer::renderTexLayerSet()
 		gAlphaMaskProgram.bind();
 		gAlphaMaskProgram.setMinimumAlpha(0.004f);
 	}
+	else
+	{
+		gGL.setAlphaRejectSettings(LLRender::CF_GREATER, 0.00f);
+	}
 
 	LLVertexBuffer::unbind();
 
@@ -1915,9 +1919,15 @@ LLGLTexture* LLTexLayerStaticImageList::getTexture(const std::string& file_name,
 		{
 			if( (image_raw->getComponents() == 1) && is_mask )
 			{
-				// Note: these are static, unchanging images so it's ok to assume
-				// that once an image is a mask it's always a mask.
-				tex->setExplicitFormat( GL_ALPHA8, GL_ALPHA );
+				// Convert grayscale alpha masks from single channel into RGBA.
+				// Fill RGB with black to allow fixed function gl calls
+				// to match shader implementation.
+				LLPointer<LLImageRaw> alpha_image_raw = image_raw;
+				image_raw = new LLImageRaw(image_raw->getWidth(),
+										   image_raw->getHeight(),
+										   4);
+
+				image_raw->copyUnscaledAlphaMask(alpha_image_raw, LLColor4U::black);
 			}
 			tex->createGLTexture(0, image_raw, 0, TRUE, LLGLTexture::LOCAL);
 
diff --git a/indra/llimage/llimage.cpp b/indra/llimage/llimage.cpp
index 916c346b7a..79949df2d0 100644
--- a/indra/llimage/llimage.cpp
+++ b/indra/llimage/llimage.cpp
@@ -673,6 +673,29 @@ void LLImageRaw::compositeUnscaled4onto3( LLImageRaw* src )
 	}
 }
 
+void LLImageRaw::copyUnscaledAlphaMask( LLImageRaw* src, const LLColor4U& fill)
+{
+	LLImageRaw* dst = this;  // Just for clarity.
+
+	llassert( 1 == src->getComponents() );
+	llassert( 4 == dst->getComponents() );
+	llassert( (src->getWidth() == dst->getWidth()) && (src->getHeight() == dst->getHeight()) );
+
+	S32 pixels = getWidth() * getHeight();
+	U8* src_data = src->getData();
+	U8* dst_data = dst->getData();
+	for ( S32 i = 0; i < pixels; i++ )
+	{
+		dst_data[0] = fill.mV[0];
+		dst_data[1] = fill.mV[1];
+		dst_data[2] = fill.mV[2];
+		dst_data[3] = src_data[0];
+		src_data += 1;
+		dst_data += 4;
+	}
+}
+
+
 // Fill the buffer with a constant color
 void LLImageRaw::fill( const LLColor4U& color )
 {
diff --git a/indra/llimage/llimage.h b/indra/llimage/llimage.h
index 5f54585005..2d98f02aa6 100644
--- a/indra/llimage/llimage.h
+++ b/indra/llimage/llimage.h
@@ -230,6 +230,11 @@ public:
 	// Src and dst are same size.  Src has 3 components.  Dst has 4 components.
 	void copyUnscaled3onto4( LLImageRaw* src );
 
+	// Src and dst are same size.  Src has 1 component.  Dst has 4 components.
+	// Alpha component is set to source alpha mask component.
+	// RGB components are set to fill color.
+	void copyUnscaledAlphaMask( LLImageRaw* src, const LLColor4U& fill);
+
 	// Src and dst can be any size.  Src and dst have same number of components.
 	void copyScaled( LLImageRaw* src );