pre-vertex normals calculation
2 ways to generate rotation matrix by x,y,z axies have different effects. Because they differ in their results. ( using dividing matrix calculate method )
Employ OpenGL texture mapping to render parts of your model more interestingly.
Implement SSD using the vertex shader. You should store the bind pose in a vertex buffer, and define a set of uniform variables for the joint transformations. For each frame, upload the latest joint transforms, and compute the transformed vertex positions and normals in the shader.