Talk:OpenGL pixel shader: Difference between revisions

::: Assuming you want to procedurally generate color values based on coords in model view space, "random" gives the impression that you want the generated values to be very noisy, i.e. have a high frequency. Broadly speaking, as long as the so generated texture is deterministic, noise is just a kind of gradient. The problem of the word "random" is that, firstly, the code still needs to decide what frequency to use: pixel shader gets called on each pixel on every scanline, which is not directly coupled to model view coordinates due to projection transformations. Secondly, if the frequency is too high (comparable to screen dpi under current projection), it will suffer greatly from aliasing, whereby any movement along z or any rotation will cause pixels to sample to completely different values, resulting in apparently changing texture. Coherent psuedo random texture with frequency cutoff is also difficult (I have a Perlin noise example in the draw sphere task). Granted, it might not be a problem because most implementations will probably just draw something static and never rotate it, but it's still easier to verify the code is doing the right thing if it's asked to draw something identifiable, say a checker pattern, stripes, concentric circles, etc. --[[User:Ledrug|Ledrug]] 03:50, 26 October 2011 (UTC)

:::: Yes, I want noise, and I want the noise for any one pixel to tend to change significantly from frame to frame. I do not care much about artifacts if these conditions are met. I do not care if one's mental model allows them to see this information as deterministic. Does this help? Do you have any suggested changes in the wording, with this in mind? Thanks. --[[User:Rdm|Rdm]] 12:40, 26 October 2011 (UTC)