In this tutorial, you have learned the following:
Diffuse lighting is a simple lighting model based on the angle between the light source and the surface normal.
Surface normals are values used, per-vertex, to define the direction of the surface at a particular location. They do not have to mirror the actual normal of the mesh geometry.
Surface normals must be transformed by the inverse-transpose of the model-to-camera matrix, if that matrix can involve a non-uniform scale operation.
Light interreflection can be approximated by adding a single light intensity that has no direction.
Each vertex attribute has its own topology. In order to render these vertices in OpenGL, attribute data must be replicated so that each unique combination of attributes has a topology.
Try doing these things with the given programs.
Modify the ambient lighting tutorial, bumping the diffuse light intensity up to 1.0. See how this effects the results.
Change the shaders in the ambient lighting tutorial to use the lighting intensity correction mentioned above. Divide the diffuse color by a value, then pass larger lighting intensities to the shader. Notice how this changes the quality of the lighting.
Lambertian diffuse reflectance is a rather good model for diffuse reflectance for many surfaces. Particularly rough surfaces however do not behave in a Lambertian manor. If you are interested in modelling such surfaces, investigate the Oren-Nayar reflectance model.
vec clamp( | vec val, |
| vec minVal, | |
vec maxVal); |
This function does a clamping operation of each component of
val. All of the parameters must scalars or vectors of the
same dimensionality. This function will work with any scalar or vector type. It
returns a scalar or vector of the same dimensionality as the parameters, where each
component of val will be clamped to the closed range
[minVal, maxVal]. This is useful
for ensuring that values are in a certain range.
All components of minVal
must be smaller than the corresponding components of
maxVal.
float dot( | vec x, |
vec y); |
This function performs a vector dot product on x and
y. This always results in a scalar value. The two
parameters must have the same dimensionality and must be vectors.
vec normalize( | vec x); |
This function returns a vector in the same direction as x,
but with a length of 1. x must have a length greater than 0
(that is, it cannot be a vector with all zeros).