Limits of geometric modelling
- although graphics cards can render millions of polygons per second, the number is still insufficient for many things such as bark, terrain, skin, or an orange.
- Consider an orange:
→ just an orange coloured sphere is too simple
→ but it takes too many polygons to render every single dimple
→ in between: get a lumpy sphere and texture map everything else

Texture mapping
- surface texture
→ model surface features, not just overall shape
→ uses images to fill colours across polygons
- a texture is simply an impage with a 2d coordinate system
- each 3d object must be parameterized to match
- each part of the surface maps to some part of the texture
- the basic problem is mapping the coordinates to the model

Envoronmental mapping
- another case of texture mapping
- picture of environment for texture map
- allows simulation of reflective surfaces
- take a 360 panorama from the object of its surroundings
- superimpose the image on the surface of the object and wrap it around its edges or whatever

Others:
- bump mapping, displacement mapping..

Mapping
- image coordinates s,t and parameterization coordinates u,v that we assign to the 3d object
- texture coordinates s,t identify pixels in the texture image
- parametric coordinates u,v map the 3d surface with 2d paramters
- How to set the uv coordinates?
→ paint on the texture
⇒ software
⇒ “im not hiding im just doing my laces up”2023/11/01 - 12:22
→ code the coordinates manually
⇒ set texture coordinates for each vertex
⇒ this is what we do
→ automatically compute the coordinates
⇒ use an algorithm

some geometric stuff about mapping the rectanlge to the cylinder
mapping the rectangle to the regular objects, sphere, cylider or box, is relatively easy with a few fomulas
but we have to map it to the actual object
- can start with the inverted normal (inside normal) of the sphere, and go forward until u hit sometihng
- can also start with the normal of the object and fire vectors outward towards the simple object
- can also start from the center of the object and fire outward towards the simple object
- 1 and 3 are similar, but can get different results based on what the simple object is (sphere, cylinder, bozx)

- texture can be tiled by repeating the uv parameteriztion over the surface
- best resutls are obtained when it's seamlessly tileable

Index