fix alpha computation in chart2 getColorAsVector

The alpha value was not being shifted, and because of associativity, the
alpha color was also not being inverted before being divided by 255.

Found while doing other Color work.

This was introduced in
    commit a0842e53b999cee3cddbd209b43e313874760f0b
    Date:   Mon May 12 05:22:52 2014 +0200
    more sal_Int32 to sal_uInt32 and simplification

Change-Id: I99b9e866a4f63676e194e65d64c31fb4c0442e0a
Reviewed-on: https://gerrit.libreoffice.org/50245
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 5 insertions, 4 deletions

diff --git a/chart2/source/view/main/GL3DRenderer.cxx b/chart2/source/view/main/GL3DRenderer.cxx
index b1b8510347c6..9067553dd588 100644
--- a/chart2/source/view/main/GL3DRenderer.cxx
+++ b/chart2/source/view/main/GL3DRenderer.cxx
@@ -44,10 +44,11 @@ GLfloat texCoords[] = {
 
 glm::vec4 getColorAsVector(sal_uInt32 nColor)
 {
-    return glm::vec4(((nColor & 0x00FF0000) >> 16) / 255.0f,
-            ((nColor & 0x0000FF00) >> 8) / 255.0f,
-            (nColor & 0x000000FF) / 255.0f,
-            (0xFF - (nColor & 0xFF000000)/255.0));
+    auto red   = ((nColor & 0x00FF0000) >> 16) / 255.0f;
+    auto green = ((nColor & 0x0000FF00) >> 8) / 255.0f;
+    auto blue  = (nColor & 0x000000FF) / 255.0f;
+    auto alpha = (0xFF - ((nColor & 0xFF000000) >> 24)) / 255.0;
+    return glm::vec4(red, green, blue, alpha);
 }
 
 }