Can you elaborate a bit? I've done GLSL fragment code, but never touched the
vertex code...
Thank you,
Patrick
On Jan 19, 2011, at 3:04 PM, Patrick Sheffield wrote:
> Sorry, I meant to change the Subject: line...
>
> Here's an example, I just tossed an image into the image input. And I'm not
> entirely sure I got my coordinates and interpolations correct, but it's sort
> of like this.
>
> Thank you for your help...
>
> Patrick
>
> <triangles1.zip>
>
> On Jan 19, 2011, at 1:12 PM, Achim Breidenbach wrote:
>
>> Hi Patrick,
>>
>> you can use a "GLSL Grid"- patch to generate the a vertices grid. In the
>> vertex code you can read in the pixel color from your image and put them
>> into a varying vec4 variable. that gets interpolated by hardware for each
>> pixel calculated by the fragment shader. Do you have an example composition
>> where we can see what the result should look like?
>>
>> best,
>>
>> Achim Breidenbach
>> Boinx Software
>>
>> On 19.01.2011, at 21:14, Patrick Sheffield wrote:
>>
>>>
>>> Is there a way in Quartz Composer to draw a (right) triangle of size X that
>>> is Gouraud or Smooth shaded between the 3 specified corner values.
>>> Actually, I will want to draw an entire "sheet" of them, but I'll start
>>> with just one.
>>>
>>> I can do so with a CI Kernel program, but it involves a silly amount of
>>> math interpolating the coloration between the vertices, especially when I
>>> am sure this can be done in hardware...
>>>
>>> As an FYI, here's the CI Kernel code - feeding it an image with the RGB
>>> values pre-plugged at size intervals. It's not efficient to be doing 4
>>> texture reads for each pixel, then interpolating to determine the color...
>>>
>>> Any thoughts? thanks,
>>>
>>> Patrick
>>>
>>> kernel vec4 triangle(sampler image, float size)
>>> {
>>> vec2 uv = samplerCoord(image);
>>> vec2 auv = floor(uv/size) * size;
>>> vec2 duv = auv + size;
>>> vec2 buv = vec2(duv.x,auv.y);
>>> vec2 cuv = vec2(auv.x,duv.y);
>>>
>>> vec2 s = mod(uv, size);
>>>
>>> vec3 a = sample(image, auv).rgb;
>>> vec3 b = sample(image, buv).rgb;
>>> vec3 c = sample(image, cuv).rgb;
>>> vec3 d = sample(image, duv).rgb;
>>>
>>> vec3 pix = (s.x + s.y) < size ?
>>> mix(mix(a, b, s.x/(size-s.y)), c, s.y/size)
>>> :
>>> mix(b, mix(c, d, (s.x-(size-s.y))/(size-(size-s.y))), s.y/size);
>>>
>>> return vec4(pix,1.0);
>>>
>>> }
>>>
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