example. ray-marching for different types of rays [ag-001D]

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A view ray has the origin at the camera, the direction is determined by the pixel on the screen that it passes through. It may intersect with a surface in the scene, and the information obtained from the intersection is used to determine the color of the corresponding pixel on the screen.

A secondary ray typically originates from a point on a surface and its direction is determined by the type of ray. For instance, a shadow ray is cast towards a light source to determine if the point is in shadow, while a reflection ray and a refraction ray follow directions based on optics. The information obtained from secondary rays helps determine the color of the corresponding pixel that the view ray passes through.