Don't compute mipmap for inexistant image color components

diff --git a/simgear/scene/material/mipmap.cxx b/simgear/scene/material/mipmap.cxx
index b7ba9a7cdc5623e5cfacedb810b32e65d3593180..9c087cf305b1bf41c6532ed932e6b3a8e5d536fe 100644 (file)
--- a/simgear/scene/material/mipmap.cxx
+++ b/simgear/scene/material/mipmap.cxx
@@ -212,30 +212,35 @@ osg::Vec4::value_type computeComponent( int c, osg::Vec4 colors[2][2][2], bool c
     return 0;\r
 }\r
 \r
-osg::Vec4 computeColor( osg::Vec4 colors[2][2][2], bool colorValid[2][2][2], MipMapTuple attrs )\r
+osg::Vec4 computeColor( osg::Vec4 colors[2][2][2], bool colorValid[2][2][2], MipMapTuple attrs, GLenum pixelFormat )\r
 {\r
     osg::Vec4 result;\r
+    unsigned int nbComponents = osg::Image::computeNumComponents( pixelFormat );\r
     result[0] = computeComponent( 0, colors, colorValid, attrs.get<0>() );\r
-    result[1] = computeComponent( 1, colors, colorValid, attrs.get<1>() );\r
-    result[2] = computeComponent( 2, colors, colorValid, attrs.get<2>() );\r
-    result[3] = computeComponent( 3, colors, colorValid, attrs.get<3>() );\r
+    if ( nbComponents >= 2 )\r
+        result[1] = computeComponent( 1, colors, colorValid, attrs.get<1>() );\r
+    if ( nbComponents >= 3 )\r
+        result[2] = computeComponent( 2, colors, colorValid, attrs.get<2>() );\r
+    if ( nbComponents == 4 )\r
+        result[3] = computeComponent( 3, colors, colorValid, attrs.get<3>() );\r
     return result;\r
 }\r
 \r
 osg::Image* computeMipmap( osg::Image* image, MipMapTuple attrs )\r
 {\r
     bool computeMipmap = false;\r
+    unsigned int nbComponents = osg::Image::computeNumComponents( image->getPixelFormat() );\r
     if ( attrs.get<0>() != AUTOMATIC &&\r
-        attrs.get<1>() != AUTOMATIC &&\r
-        attrs.get<2>() != AUTOMATIC &&\r
-        attrs.get<3>() != AUTOMATIC )\r
+        ( attrs.get<1>() != AUTOMATIC || nbComponents < 2 ) &&\r
+        ( attrs.get<2>() != AUTOMATIC || nbComponents < 3 ) &&\r
+        ( attrs.get<3>() != AUTOMATIC || nbComponents < 4 ) )\r
     {\r
         computeMipmap = true;\r
     }\r
     else if ( attrs.get<0>() != AUTOMATIC ||\r
-        attrs.get<1>() != AUTOMATIC ||\r
-        attrs.get<2>() != AUTOMATIC ||\r
-        attrs.get<3>() != AUTOMATIC )\r
+        ( attrs.get<1>() != AUTOMATIC && nbComponents >= 2 ) ||\r
+        ( attrs.get<2>() != AUTOMATIC && nbComponents >= 3 ) ||\r
+        ( attrs.get<3>() != AUTOMATIC && nbComponents == 4 ) )\r
     {\r
         throw BuilderException("invalid mipmap control function combination");\r
     }\r
@@ -335,7 +340,7 @@ osg::Image* computeMipmap( osg::Image* image, MipMapTuple attrs )
                         }\r
 \r
                         unsigned char *ptr = imageData( dest, image->getPixelFormat(), image->getDataType(), ns, nt, image->getPacking(), i/2, j/2, k/2 );\r
-                        osg::Vec4 color = computeColor( colors, colorValid, attrs );\r
+                        osg::Vec4 color = computeColor( colors, colorValid, attrs, image->getPixelFormat() );\r
                         setColor( ptr, image->getPixelFormat(), image->getDataType(), color );\r
                     }\r
                 }\r