// Given a root (aa) and two adjacent vertices (bb, cc), computer the normal for aa
private static OMV.Vector3 MakeNormal(Vert aa, Vert bb, Vert cc)
{
OMV.Vector3 mm = aa.Position - bb.Position;
OMV.Vector3 nn = aa.Position - cc.Position;
OMV.Vector3 theNormal = OMV.Vector3.Cross(mm, nn);
theNormal.Normalize();
return(theNormal);
}
private void UpdateRegionTerrainMesh(RegionContextBase rcontext, RegionRenderInfo rri)
{
TerrainInfoBase ti = rcontext.TerrainInfo;
rri.terrainVertices = new float[3 * ti.HeightMapLength * ti.HeightMapWidth];
rri.terrainTexCoord = new float[2 * ti.HeightMapLength * ti.HeightMapWidth];
rri.terrainNormal = new float[3 * ti.HeightMapLength * ti.HeightMapWidth];
int nextVert = 0;
int nextTex = 0;
int nextNorm = 0;
for (int xx = 0; xx < ti.HeightMapLength; xx++)
{
for (int yy = 0; yy < ti.HeightMapWidth; yy++)
{
rri.terrainVertices[nextVert + 0] = (float)xx / ti.HeightMapLength * rcontext.Size.X;
rri.terrainVertices[nextVert + 1] = (float)yy / ti.HeightMapWidth * rcontext.Size.Y;
rri.terrainVertices[nextVert + 2] = ti.HeightMap[xx, yy];
nextVert += 3;
rri.terrainTexCoord[nextTex + 0] = xx / ti.HeightMapLength;
rri.terrainTexCoord[nextTex + 1] = yy / ti.HeightMapWidth;
nextTex += 2;
rri.terrainNormal[nextNorm + 0] = 0f; // simple normal pointing up
rri.terrainNormal[nextNorm + 1] = 1f;
rri.terrainNormal[nextNorm + 2] = 0f;
nextNorm += 3;
}
}
// Create the quads which make up the terrain
rri.terrainIndices = new UInt16[4 * ti.HeightMapLength * ti.HeightMapWidth];
int nextInd = 0;
for (int xx = 0; xx < ti.HeightMapLength - 1; xx++)
{
for (int yy = 0; yy < ti.HeightMapWidth - 1; yy++)
{
rri.terrainIndices[nextInd + 0] = (UInt16)((yy + 0) + (xx + 0) * ti.HeightMapLength);
rri.terrainIndices[nextInd + 1] = (UInt16)((yy + 1) + (xx + 0) * ti.HeightMapLength);
rri.terrainIndices[nextInd + 2] = (UInt16)((yy + 1) + (xx + 1) * ti.HeightMapLength);
rri.terrainIndices[nextInd + 3] = (UInt16)((yy + 0) + (xx + 1) * ti.HeightMapLength);
nextInd += 4;
}
}
rri.terrainWidth = ti.HeightMapWidth;
rri.terrainLength = ti.HeightMapLength;
// Calculate normals
// Take three corners of each quad and calculate the normal for the vector
// a--b--e--...
// | | |
// d--c--h--...
// The triangle a-b-d calculates the normal for a, etc
int nextQuad = 0;
int nextNrm = 0;
for (int xx = 0; xx < ti.HeightMapLength - 1; xx++)
{
for (int yy = 0; yy < ti.HeightMapWidth - 1; yy++)
{
OMV.Vector3 aa, bb, cc;
int offset = rri.terrainIndices[nextQuad + 0] * 3;
aa.X = rri.terrainVertices[offset + 0];
aa.Y = rri.terrainVertices[offset + 1];
aa.Z = rri.terrainVertices[offset + 2];
offset = rri.terrainIndices[nextQuad + 1] * 3;
bb.X = rri.terrainVertices[offset + 0];
bb.Y = rri.terrainVertices[offset + 1];
bb.Z = rri.terrainVertices[offset + 2];
offset = rri.terrainIndices[nextQuad + 3] * 3;
cc.X = rri.terrainVertices[offset + 0];
cc.Y = rri.terrainVertices[offset + 1];
cc.Z = rri.terrainVertices[offset + 2];
OMV.Vector3 mm = aa - bb;
OMV.Vector3 nn = aa - cc;
OMV.Vector3 theNormal = -OMV.Vector3.Cross(mm, nn);
theNormal.Normalize();
rri.terrainNormal[nextNrm + 0] = theNormal.X; // simple normal pointing up
rri.terrainNormal[nextNrm + 1] = theNormal.Y;
rri.terrainNormal[nextNrm + 2] = theNormal.Z;
nextNrm += 3;
nextQuad += 4;
}
rri.terrainNormal[nextNrm + 0] = 1.0f;
rri.terrainNormal[nextNrm + 1] = 0.0f;
rri.terrainNormal[nextNrm + 2] = 0.0f;
nextNrm += 3;
}
}
