From ceba688cb54016a9f6ff70761b2c459698bfd7f0 Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Thu, 10 Jun 2010 00:15:48 -0700 Subject: [PATCH] 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. --- src/mesa/swrast/s_readpix.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/src/mesa/swrast/s_readpix.c b/src/mesa/swrast/s_readpix.c index 368311e14dd..6ad9aceec77 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 */ -- 2.30.2