Mesh.SetInds

void SetInds(UInt32[] indices)

Assigns the face indices for this Mesh! Faces are always triangles, there are only ever three indices per face. This function will create a index buffer object on the graphics card. If you’re calling this a second time, the buffer will be marked as dynamic and re-allocated. If you’re calling this a third time, the buffer will only re-allocate if the buffer is too small, otherwise it just copies in the data!


UInt32[] indices	A list of face indices, must be a multiple of 3. Each index represents a vertex from the array assigned using SetVerts.

Examples

Procedurally generating a wavy grid

Wavy Grid

Here, we’ll generate a grid mesh using Mesh.SetVerts and Mesh.SetInds! This is a common example of creating a grid using code, we’re using a sin wave to make it more visually interesting, but you could also substitute this for something like sampling a heightmap, or a more interesting mathematical formula!

Note: x+y*gridSize is the formula for 2D (x,y) access of a 1D array that represents a grid.

const int   gridSize = 8;
const float gridMaxF = gridSize-1;
Vertex[] verts = new Vertex[gridSize*gridSize];
uint  [] inds  = new uint  [gridSize*gridSize*6];

for (int y = 0; y < gridSize; y++) {
for (int x = 0; x < gridSize; x++) {
	// Create a vertex on a grid, centered about the origin. The dimensions extends
	// from -0.5 to +0.5 on the X and Z axes. The Y value is then sampled from 
	// a sin wave using the x and y values.
	//
	// The normal of the vertex is then calculated from the derivative of the Y 
	// value!
	verts[x+y*gridSize] = new Vertex(
		new Vec3(
			x/gridMaxF-0.5f,
			SKMath.Sin((x+y) * 0.7f)*0.1f,
			y/gridMaxF-0.5f),
		new Vec3(
			-SKMath.Cos((x+y) * 0.7f),
			1,
			-SKMath.Cos((x+y) * 0.7f)).Normalized,
		new Vec2(
			x / gridMaxF,
			y / gridMaxF));

	// Create triangle face indices from the current vertex, and the vertices
	// on the next row and column! Since there is no 'next' row and column on
	// the last row and column, we guard this with a check for size-1.
	if (x<gridSize-1 && y<gridSize-1)
	{
		int ind = (x+y*gridSize)*6;
		inds[ind  ] = (uint)((x+1)+(y+1)*gridSize);
		inds[ind+1] = (uint)((x+1)+(y  )*gridSize);
		inds[ind+2] = (uint)((x  )+(y+1)*gridSize);

		inds[ind+3] = (uint)((x  )+(y+1)*gridSize);
		inds[ind+4] = (uint)((x+1)+(y  )*gridSize);
		inds[ind+5] = (uint)((x  )+(y  )*gridSize);
	}
} }
demoProcMesh = new Mesh();
demoProcMesh.SetData(verts, inds);

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