Hello,
I came across this part of the code in s_texfilter.c when trying to debug a
glitch in the texture application -
/* DEBUG CODE: Verify that lambda[] is monotonic.
* We can't really use this because the inaccuracy in the LOG2 function
* causes this test to fail, yet the resulting texturing is correct.
*/
if (n > 1) {
GLuint i;
printf("lambda delta = %g\n", lambda[0] - lambda[n-1]);
if (lambda[0] >= lambda[n-1]) { /* decreasing */
for (i = 0; i < n - 1; i++) {
ASSERT((GLint) (lambda[i] * 10) >= (GLint) (lambda[i+1] * 10));
}
}
else { /* increasing */
for (i = 0; i < n - 1; i++) {
ASSERT((GLint) (lambda[i] * 10) <= (GLint) (lambda[i+1] * 10));
}
}
}
I've encountered a situation where lambda drops below zero during a
non-monotonic span and the results are disastrous and not "yet the resulting
texturing is correct" !
Has anyone seen something like this?
Thank you...
Btw - My name is nir, and I'm working on linux-opengl-HW compatibility tests,
and am using MESA as reference code - I came upon this when trying to mipmap
between bitmaps of solid color and see blue where red should be :) If u need
code examples call me up.
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