Re: [Mesa3d-dev] divide by zero in triangle.c

[Brian P. <br...@va...>]

Klaus Niederkrueger wrote:
> 
> Hi,
> 
> On monday and tuesday I have two free days, so I will fix the error then (at least I hope).
> The fix should be pretty easy, if   dx_tex == dy_tex == 0.0f, then the program does not move over the texture, so one can fill the whole array rgba[n] with the corresponding (constant) texel, indeed if only dy_tex == 0.0f one can simplify the fill-code a lot, but I don't know if this case is generic enough to be worked into the code.
> 
> By the way: Three questions.
> 
> 1. When this bug happens, what is the value of dTdx, dvdx?
> 
> 2. I usually test my code-changes by typing "LD_PRELOAD=~/Mesa/src/.libs/libGL.so demoprog". How can I tell "gdb" that I want to use this library when debugging?

I use LD_LIBRARY_PATH to point to my libGL.so and gdb (version=19991004) seems
to find it just fine.  I can't set breakpoints in Mesa code until the library
has actually been loaded so I'll first break in main() and then set my Mesa
breakpoints when I've stopped in main().  Hope this helps.


> 3. This is a suggestions. I believe that the MIPMAPPING-code calculates which texture-level to use for every pixel it draws. Since the level of detail should be a monotone function over the array rgba[n], wouldn't it be possible (in the case GL_NEAREST_MIPMAP_NEAREST and GL_LINEAR_MIPMAP_NEAREST) to calculate the lod at the beginning of the array and at the end of the array and if lod is equal at these points, to just fill the whole array with a constant level of detail?

Yes, I believe that's true.

-Brian