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authorEric Anholt <eric@anholt.net>2010-06-10 00:15:48 -0700
committerEric Anholt <eric@anholt.net>2010-06-10 00:22:00 -0700
commitceba688cb54016a9f6ff70761b2c459698bfd7f0 (patch)
tree885aaae8993d7198dc6a0e0c09b323ed4e1f6a10 /src/mesa/swrast
parent94731797c671d6e46e3e0c94c1a0cec5071c0ac3 (diff)
swrast: When reading from a 0-bits r,g,b channel, return 0 not 1.
It looks like we were reading a fractional value, multiplying by an enormous negative value, then stuffing that value into a bitfield assuming it was already clamped. This becomes relevant for GL_ALPHA or R/RG FBOs.
Diffstat (limited to 'src/mesa/swrast')
-rw-r--r--src/mesa/swrast/s_readpix.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/src/mesa/swrast/s_readpix.c b/src/mesa/swrast/s_readpix.c
index 368311e14d..6ad9aceec7 100644
--- a/src/mesa/swrast/s_readpix.c
+++ b/src/mesa/swrast/s_readpix.c
@@ -265,10 +265,18 @@ adjust_colors(const struct gl_framebuffer *fb, GLuint n, GLfloat rgba[][4])
const GLuint rShift = 8 - fb->Visual.redBits;
const GLuint gShift = 8 - fb->Visual.greenBits;
const GLuint bShift = 8 - fb->Visual.blueBits;
- const GLfloat rScale = 1.0F / (GLfloat) ((1 << fb->Visual.redBits ) - 1);
- const GLfloat gScale = 1.0F / (GLfloat) ((1 << fb->Visual.greenBits) - 1);
- const GLfloat bScale = 1.0F / (GLfloat) ((1 << fb->Visual.blueBits ) - 1);
+ GLfloat rScale = 1.0F / (GLfloat) ((1 << fb->Visual.redBits ) - 1);
+ GLfloat gScale = 1.0F / (GLfloat) ((1 << fb->Visual.greenBits) - 1);
+ GLfloat bScale = 1.0F / (GLfloat) ((1 << fb->Visual.blueBits ) - 1);
GLuint i;
+
+ if (fb->Visual.redBits == 0)
+ rScale = 0;
+ if (fb->Visual.greenBits == 0)
+ gScale = 0;
+ if (fb->Visual.blueBits == 0)
+ bScale = 0;
+
for (i = 0; i < n; i++) {
GLint r, g, b;
/* convert float back to ubyte */