Otherwise, if you don’t want to use these instructions (i.e writing for ATi cards), I think that the log2 instructions will be part of your equation. I do not believe on nv40 (and thus the RSX) these instructions are macros, thus are a viable choice for Killzone2. While searching for the Cg/GLSL function-names of the unpack/pack instructions, I stumbled on some blog, where someone stated that on his GF80 the pack/unpack instructions take 4-10 cycles (“probably internal bit-shifting”). This function takes three arguments: a lower boundary (edge0), an upper boundary (edge1) and a value as a source for the interpolation.Yup, this one does the trick, and I verified the output values:Ĭhecked what values should be seen with this x86 asm code:Īnd eax,11111100000000000000000000000000bĪnd ebx,00000000011111111110000000000000b The first two parameters of the mix function are the colours to be mixed, and the last parameter specifies how the colours are going to be mixed, according to the following expression. We are going to use GLSL mix function to do a linear interpolation on the colors as seen below. To fix this we can use a function with smoother transitions as depicted in the figure below. The shader will decide which color to use based on the fractional part of the texture coordinates. This causes the shader to be stopped and nothing will be written in any of the buffers, both color and depth.įor instance we can write a shader to paint stripes on an object. Varying this value and the threshold alters the number of grid cells and their width, respectively. This last value, 0.1, controls the width of the lines drawn. The fragment shader then selects only those pixels that have one of the texture coordinates with a fractional value below 0.1, painting these with blue color. The density of the grid is defined by a multiplication factor applied to the texture coordinates. These shaders can be useful for debugging when texturing with an image provides unexpected results.įor instance, assume that we want to obtain a grid effect as shown in the image below. Red will be used for the s coordinate, and green for the t coordinate. Hence in the application we need to treat them as such, i.e.įor instance, the figure below shows a plane, an elephant, and the teapot, with their texture coordinates. Texture coordinates are just another vertex attribute, much like normals. Here we will see a couple examples of how texture coordinates can be used on their own. However texture coordinates are not restricted to perform this mapping.

If the container is not empty, the function never throws exceptions (no-throw guarantee).

Concurrently accessing or modifying other elements is safe, although iterating ranges that include the removed element is not.

Vec2 pack