Terrain Normals

Graphics and GPU Programming Programming

Started by AN_D_K August 05, 2003 06:00 PM

2 comments, last by AN_D_K 20 years, 8 months ago

158

Author

August 05, 2003 06:00 PM

I know that on a terrain mesh that each vertex has the average normal of all the triangles connected too it. All the vertices within the mesh are connected to 6 triangles and this has let me make a simple algorithm to get the values for it. What is troubling me is how to get the normals for the vertices that are on the outsides of the mesh as they are not connected to 6 triangles. How to I make an algorithm for these that will compliment my previous one?

budipro

122

August 05, 2003 10:49 PM

If you use triangle list and indices, then it should be easy to calculate the normals. Just loop through the indices and average the vertex normals those indices point to.

I haven''t figured out the way if you are not using list and indices. It seems quite complicated.

Here is the sample using list and indices:

for (int i = 0; i < indices.Length; i+=3)				{					normal = (CalcNormal(verts[indices[i+1]], verts[indices[i+2]], verts[indices[i]]));					verts[indices[i]].SetNormal(Vector3.Add(verts[indices[i]].GetNormal(), normal));					verts[indices[i+1]].SetNormal(Vector3.Add(verts[indices[i+1]].GetNormal(), normal));					verts[indices[i+2]].SetNormal(Vector3.Add(verts[indices[i+2]].GetNormal(), normal));					verts[indices[i]].SetNormal(Vector3.Normalize(verts[indices[i]].GetNormal()));					verts[indices[i+1]].SetNormal(Vector3.Normalize(verts[indices[i+1]].GetNormal()));					verts[indices[i+2]].SetNormal(Vector3.Normalize(verts[indices[i+2]].GetNormal()));				}

joanusdmentia

1,060

August 06, 2003 01:25 AM

2 ways come to mind. You could assume that the normal of the non-existent triangles simply point upwards. Alternatively, just exclude them from the calculation (ie. average only the normals that you do have). How you do it is really up to you.

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_DarkWIng_

602

August 06, 2003 03:05 AM

If you are using heightmap for terrain loop up "finite distance" approach for generation normals. It''s been discussed on this forums alot of times.

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Terrain Normals

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Terrain Normals

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