I have a triangulated 2D polygon and a 3D terrain mode as a regular grid. The polygon is e.g. a forrest. How can I render that ON the terrain without textures?
As the model has to be zoomed in and out quickly, textures would make things way more complicated, dithered and slow.
Triangulation of the polygon in the the exact grid could work, but that’s a lot of effort and many, many triangles in the end.
A general triangulation is bad, as it will not go along nicely Wirth the terrain which will peak through the polygon triangles.
A fragment shader deciding if a pixel is inside or outside of that polygon is perhaps possible, but I have to make sure, the texture somehow describing the polygon x and y values is never compressed.
Displacement fragment shader for the terrain?