what's the difference between material and texture?
In Computer graphics, what's the difference between material and texture?
Answer
In OpenGL, a material is a set of coefficients that define how the lighting model interacts with the surface. In particular, ambient, diffuse, and specular coefficients for each color component (R,G,B) are defined and applied to a surface and effectively multiplied by the amount of light of each kind/color that strikes the surface. A final emmisivity coefficient is then added to each color component that allows objects to appear luminous without actually interacting with other objects.
A texture, on the other hand, is a set of 1-, 2-, 3-, or 4- dimensional bitmap (image) data that is applied and interpolated on to a surface according to texture coordinates at the vertices. Texture data alters the color of the surface whether or not lighting is enabled (and depending on the texture mode, e.g. decal, modulate, etc.). Textures are used frequently to provide sub-polygon level detail to a surface, e.g. applying a repeating brick and mortar texture to a quad to simulate a brick wall, rather than modeling the geometry of each individual brick.
In the classical (fixed-pipeline) OpenGL model, textures and materials are somewhat orthogonal. In the new programmable shader world, the line has blurred quite a bit. Frequently textures are used to influence lighting in other ways. For example, bump maps are textures that are used to perturb surface normals to effect lighting, rather than modifying pixel color directly as a regular "image" texture would.