The top of the triangle should correspond with the top-center of the texture image so we take (0.5,1.0) as its texture coordinate. The same applies to the bottom-right side with a (1,0) texture coordinate. We want the bottom-left side of the triangle to correspond with the bottom-left side of the texture so we use the (0,0) texture coordinate for the triangle's bottom-left vertex. ![]() We specify 3 texture coordinate points for the triangle. The following image shows how we map texture coordinates to the triangle: Texture coordinates start at (0,0) for the lower left corner of a texture image to (1,1) for the upper right corner of a texture image. Retrieving the texture color using texture coordinates is called sampling. Texture coordinates range from 0 to 1 in the x and y axis (remember that we use 2D texture images). Fragment interpolation then does the rest for the other fragments. Each vertex should thus have a texture coordinate associated with them that specifies what part of the texture image to sample from. In order to map a texture to the triangle we need to tell each vertex of the triangle which part of the texture it corresponds to. ![]() Next to images, textures can also be used to store a large collection of arbitrary data to send to the shaders, but we'll leave that for a different topic.īelow you'll see a texture image of a brick wall mapped to the triangle from the previous chapter. ![]() ![]() Because we can insert a lot of detail in a single image, we can give the illusion the object is extremely detailed without having to specify extra vertices. A texture is a 2D image (even 1D and 3D textures exist) used to add detail to an object think of a texture as a piece of paper with a nice brick image (for example) on it neatly folded over your 3D house so it looks like your house has a stone exterior. What artists and programmers generally prefer is to use a texture. This takes up a considerable amount of extra overhead, since each model needs a lot more vertices and for each vertex a color attribute as well. However, to get a fair bit of realism we'd have to have many vertices so we could specify a lot of colors. We learned that to add more detail to our objects we can use colors for each vertex to create some interesting images.
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