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From: Brian P. <br...@va...> - 2001-01-04 16:19:47
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Gareth Hughes wrote: > > Here's a good one. I'm running the blendFunc test with the Radeon > driver, it's passing just fine at 16bpp, and failing at 32bpp. All of > the errors are on the alpha channel, but the pixels being read back > contain the expected values. I'm suspecting the problem lies somewhere > after the driver reads the pixels from the framebuffer in the span > functions, and before glean gets the pixel values back. > > Here's the (0,0) pixel data being read back, obviously containing alpha > values (in ARGB8888 format): > > x=1 y=1 p=0x6fb39c21 > x=1 y=1 p=0x00000000 > x=1 y=1 p=0x6fb39c21 > x=1 y=1 p=0x6fb39c21 > x=1 y=1 p=0x6fb39c21 > x=1 y=1 p=0x18974e06 > x=1 y=1 p=0x6fb39c21 > x=1 y=1 p=0x561b4e1a > x=1 y=1 p=0x6fb39c21 > x=1 y=1 p=0x18272207 > x=1 y=1 p=0x6fb39c21 > x=1 y=1 p=0x568b7919 > x=1 y=1 p=0x6fb39c21 > x=1 y=1 p=0x304e440e > > And here's the test failure message: > > blendFunc: FAIL rgba8, db, z24, win+pmap, id 0 > source factor = GL_ZERO, dest factor = GL_ZERO > Readback had 8 bits in error; blending had 0 bits in error. > > First failing pixel is at row 0 column 0 > Actual values are (0.698039, 0.678431, 0.678431, 0) > Expected values are (0.698039, 0.678431, 0.678431, 0.239216) > Errors are (0, 0, 0, 0.239216) > Source values are (0.176471, 0.886275, 0.988235, 0.252338) > Destination values are (0.698039, 0.678431, 0.678431, 0.239216) > > Any ideas? This doesn't appear to be a driver error, and I haven't seen > anything like this before. Check the call to Mesa's gl_create_framebuffer() function and make sure you're not telling Mesa to maintain a software alpha channel. That could cause trouble. -Brian |