MESA_GLX_ALPHA_BITS env var to force visual with alpha channel

diff --git a/src/mesa/drivers/x11/fakeglx.c b/src/mesa/drivers/x11/fakeglx.c
index cd26bade30b25e0a3bb95c75c702ec33be5974ea..1933fed0673ed3d5c3e8b381a330cd5521187266 100644 (file)
--- a/src/mesa/drivers/x11/fakeglx.c
+++ b/src/mesa/drivers/x11/fakeglx.c
@@ -378,6 +378,18 @@ default_depth_bits(void)
    return zBits;
 }
 
+static GLint
+default_alpha_bits(void)
+{
+   int aBits;
+   const char *aEnv = _mesa_getenv("MESA_GLX_ALPHA_BITS");
+   if (aEnv)
+      aBits = _mesa_atoi(aEnv);
+   else
+      aBits = 0;
+   return aBits;
+}
+
 static GLint
 default_accum_bits(void)
 {
@@ -400,6 +412,7 @@ create_glx_visual( Display *dpy, XVisualInfo *visinfo )
    int vislevel;
    GLint zBits = default_depth_bits();
    GLint accBits = default_accum_bits();
+   GLboolean alphaFlag = default_alpha_bits() > 0;
 
    vislevel = level_of_visual( dpy, visinfo );
    if (vislevel) {
@@ -437,7 +450,7 @@ create_glx_visual( Display *dpy, XVisualInfo *visinfo )
          /* can be done?  They should use glXChooseVisual(). */
          return save_glx_visual( dpy, visinfo,
                                  GL_TRUE,   /* rgb */
-                                 GL_FALSE,  /* alpha */
+                                 alphaFlag, /* alpha */
                                  GL_TRUE,   /* double */
                                  GL_FALSE,  /* stereo */
                                  zBits,
@@ -1013,7 +1026,7 @@ choose_visual( Display *dpy, int screen, const int *list, GLboolean fbConfig )
            parselist++;
             {
                GLint size = *parselist++;
-               alpha_flag = size>0 ? 1 : 0;
+               alpha_flag = size ? GL_TRUE : GL_FALSE;
             }
            break;
         case GLX_DEPTH_SIZE:
@@ -1223,6 +1236,10 @@ choose_visual( Display *dpy, int screen, const int *list, GLboolean fbConfig )
          depth_size = default_depth_bits();
       }
 
+      if (!alpha_flag) {
+         alpha_flag = default_alpha_bits() > 0;
+      }
+
       /* we only support one size of stencil and accum buffers. */
       if (stencil_size > 0)
          stencil_size = STENCIL_BITS;