Gouraud
Phong
The smooth shading algorithm used in OpenGL
glShadeModel( GL_SMOOTH )
Adv: better specular highlight, not
in OpenGL
Lighting is calculated for each of the polygon vertices
Compute lighting during rasterization
Colors are interpolated for interior pixels.. (normals are not needed for interior
Interpolate the normals across polygon
Per-vertex lighting calculation
Instead of interpolation, we calculate lighting for each pixel inside the polygon
(per-pixel lighting)
Normal is needed for each vertex
Need normals for all the pixels
Per-vertex normal can be computed by
averaging the adjacent face normals
Need to map the normal back to world or eye space
Problem--Lighting in the polygon interior can be
Inaccurate
Problem: Slow---Not supported by OpenGL, but now graphics cards have pixel shaders that can be used to do this quickly
Gouraud Shading is effective for shading surfaces which reflect light diffusely. Specular reflections can be modelled using Gouraud Shading, but the shape of the specluar highlight produced is dependent on the relative positions of the underlying polygons. The advantage of Gouraud shading is that it is computationally the less expensive of the two model, only requring the evaluation of the intensity equation at the polygon vertices, and then bilinear interpolation of these values for each pixels. Phong Shading produces highlights which are much less dependent on the underlying polygons. However, more calculation are required, involving the interpolation of the surface normal and the evaluation of the intensity function for each pixel.
Phong Shading produces highlights which are much less dependent on the underlying polygons. However, more calculation are required, involving the interpolation of the surface normal and the evaluation of the intensity function for each pixel.
Hai phong city is not in china
Dang Phong died in 2010.
Dang Phong was born in 1937.
The population of Hai Phong is 1,884,685.
Phong Bui was born in 1964.
Billy Phong goes by Bobbibong.
Pho Phong has written: 'Troi phat'
Buu Phong Temple was created in 1829.
The population of Phong Tho District is 49,169.
The population of Nam Phong District is 112,414.