![]() 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. Since vectors represent directions, the origin of the vector does not change its value.We learned that to add more detail to our objects we can use colors for each vertex to create some interesting images. Because it is more intuitive to display vectors in 2D (rather than 3D) you can think of the 2D vectors as 3D vectors with a z coordinate of 0. If a vector has 2 dimensions it represents a direction on a plane (think of 2D graphs) and when it has 3 dimensions it can represent any direction in a 3D world.īelow you'll see 3 vectors where each vector is represented with (x,y) as arrows in a 2D graph. Vectors can have any dimension, but we usually work with dimensions of 2 to 4. The directions for the treasure map thus contains 3 vectors. You can think of vectors like directions on a treasure map: 'go left 10 steps, now go north 3 steps and go right 5 steps' here 'left' is the direction and '10 steps' is the magnitude of the vector. A vector has a direction and a magnitude (also known as its strength or length). In its most basic definition, vectors are directions and nothing more. If the subjects are difficult, try to understand them as much as you can and come back to this chapter later to review the concepts whenever you need them. The focus of this chapter is to give you a basic mathematical background in topics we will require later on. However, to fully understand transformations we first have to delve a bit deeper into vectors before discussing matrices. When discussing matrices, we'll have to make a small dive into some mathematics and for the more mathematically inclined readers I'll post additional resources for further reading. Matrices are very powerful mathematical constructs that seem scary at first, but once you'll grow accustomed to them they'll prove extremely useful. This doesn't mean we're going to talk about Kung Fu and a large digital artificial world. There are much better ways to transform an object and that's by using (multiple) matrix objects. We could try and make them move by changing their vertices and re-configuring their buffers each frame, but that's cumbersome and costs quite some processing power. We now know how to create objects, color them and/or give them a detailed appearance using textures, but they're still not that interesting since they're all static objects. Transformations Getting-started/Transformations
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