Use 64-KiB buffer instead of 256-KiB

We only use red channel anyway, so no need to also waste space for
G, B and A.

Change-Id: I2bacef36d1e9845287a205a5f6473952ef59083e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/113552
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/slideshow/source/engine/opengl/TransitionImpl.cxx b/slideshow/source/engine/opengl/TransitionImpl.cxx
index 98d6778fd197..f8d062d34941 100644
--- a/slideshow/source/engine/opengl/TransitionImpl.cxx
+++ b/slideshow/source/engine/opengl/TransitionImpl.cxx
@@ -1473,18 +1473,18 @@ void initPermTexture(GLuint *texID)
     glBindTexture(GL_TEXTURE_2D, *texID);
 
     static bool initialized = false;
-    static unsigned char permutation2D[256*256*4];
+    static unsigned char permutation2D[256*256];
     if( !initialized ) {
       int x, y;
 
       for( y=0; y < 256; y++ )
           for( x=0; x < 256; x++ )
-              permutation2D[x*4 + y*1024] = permutation256[(y + permutation256[x]) & 0xff];
+              permutation2D[x + y*256] = permutation256[(y + permutation256[x]) & 0xff];
 
       initialized = true;
     }
 
-    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, 256, 256, 0, GL_RGBA, GL_UNSIGNED_BYTE, permutation2D );
+    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, 256, 256, 0, GL_RED, GL_UNSIGNED_BYTE, permutation2D );
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
     CHECK_GL_ERROR();