Mesa (gallium-cylindrical-wrap): softpipe: Properly implement cylindrical wrapping.

[michal]

Brian Paul wrote on 2010-02-05 18:56:
> michal wrote:
>   
>> Micha?? Kr??l wrote on 2010-02-05 17:34:
>>     
>>> Module: Mesa
>>> Branch: gallium-cylindrical-wrap
>>> Commit: f90399107eb9b54ea2c76f973ab487c38e61a5f0
>>> URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=f90399107eb9b54ea2c76f973ab487c38e61a5f0
>>>
>>> Author: Michal Krol <michal at vmware.com>
>>> Date:   Fri Feb  5 17:12:48 2010 +0100
>>>
>>> softpipe: Properly implement cylindrical wrapping.
>>>
>>> @@ -801,21 +900,23 @@ line_linear_coeff(const struct setup_context *setup,
>>>  /**
>>>   * Compute a0, dadx and dady for a perspective-corrected interpolant,
>>>   * for a line.
>>> + * v[0] and v[1] are vmin and vmax, respectively.
>>>   */
>>>  static void
>>>  line_persp_coeff(const struct setup_context *setup,
>>>                   struct tgsi_interp_coef *coef,
>>> -                 uint vertSlot, uint i)
>>> +                 uint i,
>>> +                 const float v[2])
>>>  {
>>>     /* XXX double-check/verify this arithmetic */
>>> -   const float a0 = setup->vmin[vertSlot][i] * setup->vmin[0][3];
>>> -   const float a1 = setup->vmax[vertSlot][i] * setup->vmax[0][3];
>>> +   const float a0 = v[0] * setup->vmin[0][3];
>>> +   const float a1 = v[1] * setup->vmax[0][3];
>>>     const float da = a1 - a0;
>>>     const float dadx = da * setup->emaj.dx * setup->oneoverarea;
>>>     const float dady = da * setup->emaj.dy * setup->oneoverarea;
>>>     coef->dadx[i] = dadx;
>>>     coef->dady[i] = dady;
>>> -   coef->a0[i] = (setup->vmin[vertSlot][i] -
>>> +   coef->a0[i] = (v[0] - /* XXX: <-- shouldn't that be a0? */
>>>   
>>>       
>> I have put this XXX comment, because the code in line_persp_coeff() is 
>> not consistent wih tri_persp_coeff(). Can someone double check this?
>>     
>
> It works.  I added a line drawing mode to cylwrap.c to test.
>
>   
Just noticed there are two XXX comments in the snippet. Are we talking 
about the new one in the last line of the cited code?

/* XXX: <-- shouldn't that be a0? */