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Can anyone see what I'm doing wrong here? (CI Kernel)

Gentlemen,

In this composition:

Attachment: Possible Bug.zip
Description: Zip archive


PNG image


I'm using the following kernel program to generate the plot you see on the right, from the gradient patch output that you see on the left.

kernel vec4 ramp(sampler image, float height)
{
    vec4 inputColor = sample(image, samplerCoord(image));
    vec4 result;

    float yLocation = destCoord()[1]/height;

    result.r = (yLocation < inputColor.r) ? 1.0 : 0.0;
    result.g = (yLocation < inputColor.g) ? 1.0 : 0.0;
    result.b = (yLocation < inputColor.b) ? 1.0 : 0.0;
    result.a = inputColor.a;

return result;
}


If you try moving the sliders, you'll see a couple of unexpected results.. the first and most obvious one is that the red curve is affected by the green value. The second is that if I set any of the inputs to 0.5, the peak of the corresponding curve is apparently lower than the midpoint of the output image.

Did I botch my code in some way that I'm just not seeing, or is this a bona fide CI bug?

Any ideas?

-jcr


John C. Randolph <email@hidden> (408) 914-0013
Roaming Cocoa Engineer,
Available for your projects at great Expense and Inconvenience.



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