Support masks without alpha.

1 files changed, 9 insertions, 5 deletions

diff --git a/src/mga_exa.c b/src/mga_exa.c
index ad6f5eb..c5d1705 100644
--- a/src/mga_exa.c
+++ b/src/mga_exa.c
@@ -386,11 +386,6 @@ mgaCheckComposite(int op, PicturePtr pSrcPict, PicturePtr pMaskPict,
         return FALSE;
 
     if (pMaskPict) {
-        if (!PICT_FORMAT_A(pMaskPict->format)) {
-            DEBUG_MSG(("Mask without alpha unsupported\n"));
-            return FALSE;
-        }
-
         if (!mgaCheckSourceTexture(1, pMaskPict))
             return FALSE;
 
@@ -619,6 +614,15 @@ mgaPrepareComposite(int op, PicturePtr pSrcPict, PicturePtr pMaskPict,
             blendcntl = (blendcntl & ~MGA_SRC_BLEND_MASK) | MGA_SRC_ZERO;
     }
 
+    if (!PICT_FORMAT_A(pSrcPict->format) && mgaBlendOp[op].src_alpha) {
+        int dblend = blendcntl & MGA_DST_BLEND_MASK;
+
+        if (dblend == MGA_DST_SRC_ALPHA)
+            blendcntl = (blendcntl & ~MGA_DST_BLEND_MASK) | MGA_DST_ONE;
+        else if (dblend == MGA_DST_ONE_MINUS_SRC_ALPHA)
+            blendcntl = (blendcntl & ~MGA_DST_BLEND_MASK) | MGA_DST_ZERO;
+    }
+
     WAITFIFO(4);
     OUTREG(MGAREG_TDUALSTAGE0, ds0);
     OUTREG(MGAREG_TDUALSTAGE1, ds1);