15、GPU 渲染技术：路径追踪与体积渲染详解

GPU 渲染技术：路径追踪与体积渲染详解

1. GPU 路径追踪实现

路径追踪是一种用于渲染几何图形的方法，与光线追踪类似，它也投射光线，但这些光线是从光源位置随机发射的。由于难以精确近似真实光照，我们可以使用基于蒙特卡罗的积分方案来进行近似。这种方法通过随机采样，当样本数量足够多时，积分结果会收敛到真实解。

1.1 路径追踪伪代码

For each pixel on screen
  Create a light ray from light position in a random direction 
  For the amount of traces required           
    For each object in the scene
      Check light ray for intersection 
      If intersection found
        Determine the hit point and surface normal 
        Calculate diffuse and specular comp. at hit point
        Cast shadow ray in random direction from hit point  
        Darken diffuse component based on shadow result
        Set the randomly jittered hit point as new ray origin
        Reflect the li