Unity渲染6 Bumpiness 学习笔记

• Perturb normals to simulate bumps.
• Compute normals from a height field.
• Sample and blend normal maps.
• Convert from tangent space to world space.

 

How could we make this quad appear non-flat? We could fake roughness by baking shading into the albedo texture. However, that would be completely static. If the lights change, or the objects move, so should the shading. If it doesn't, the illusion will be broken. And in case of specular reflections, even the camera isn't allowed to move.

We can change the normals to create the illusion of a curving surface. But there are only four normals per quad, one for each vertex. This can only produce smooth transitions. If we want a varied and rough surface, we need more normals.

We could subdivide our quad into smaller quads. This gives us more normals to work with. In fact, once we have more vertices, we can also move them around. Then we don't need the illusion of roughness, we can make an actual rough surface! But the sub-quads still have the same problem. Are we going to subdivide those too? That will lead to huge meshes with an enormous amount of triangles. That is fine when creating 3D models, but isn't feasible for real-time use in games.