1. Texture Mapping
We can improve the realism of graphics models by mapping a texture pattern
(image) onto the modeled object surface. We refer to this technique as texture
mapping or pattern mapping.
Adding texture mapping
to polygonal models

2. Coordinate Refence Systems
Texture mapping approaches
Texture scanning
Map the texture pattern to object surface.
Map to project to the plane
Pixel-order scanning
Map pixel areas onto object surfaces.
Map to texture space

3. Mapping
u = fu(s,t) = aus + but + cu
v = fv(s,t) = avs + bvt + cv

4. Example Surface Parameters u =  ; 0 <  < 90
v = z ; 0 < z < 1
The parametric representation of the surface
x = r cos(u) ; y = r sin(u); z = v
Map the array to the surface
u = s*90 ; v = t
Select the viewing position and perform the inverse of the
viewing transformation from from pixel coordinate to the
cylinder surface.

5. MipMaps Large texture need more memory space and more time to render.
Different resolution texture
Close regions have high resolution textures.
Far regions have low resolution textures
Level-0
Level-1
Level-2

6. Bump Mapping Bump Mapping is used to model the surface roughness.
Bump mapping usually achieved by
applying a perturbation function

7. OpenGL Textures Texture width and height are power of 2
Allows border for textures
Several image packing strategies
Right now, handles 1D and 2D textures
Could wrap or clamp textures

8. Code Exampe // During Initialization stage
glBindTexture (GL_TEXTURE_2D, 13);
glPixelStorei (GL_UNPACK_ALIGNMENT, 1);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); */
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, img_width, img_height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);

9. Code Example //At Display glEnable (GL_TEXTURE_2D);
glBindTexture (GL_TEXTURE_2D, 13);
// Start Geometry
glTexCoord2f (0.0,0.0);
glVertex3f(5.0, 7.1, 3.6);