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Originally Posted by luuckyy
Please can you explain what is a weight map ?
How do you use it ?
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Sure thing!
A weight map is a grayscale image that is used to blend smoothly between two effects. The effect could be a material, a deformation, a transform or any number of other things, but the most typical uses are materials and vertex bone weights. Any pixels that are black in the weight map use the first effect, and any pixels that are white in the weight map use the second effect. For example, if you were using a weight map to blend between a red and a blue material, black pixels in the weight map would turn the object red, blue pixels in the weight map would turn the object blue, and gray pixels in the weight map would turn the object purple as it would mix the red and blue together.
Using a weight map for bone weights works the same way. Remember, a bone is really just a transform. For example, a leg "bone" is a transformation matrix that stores the pivot point and rotation of the leg. The pelvis "bone" is the pivot and rotation of the pelvis. If you wanted to blend the vertices in a character's hip between the leg and the pelvis you could use a weight map to indicate which vertices were influenced by which; so that vertices near the thigh are almost entirely influenced by the leg, and vertices near the waist are almost entirely influenced by the pelvis, and vertices in the middle are blended between the two.
How many and what kind of weight maps you need depends on the specifics of your renderer. Many renderers need one weight map per bone, to indicated the strength of the influence of the bone on the different vertices of the model, bt other possible combinations exist.