protected void GenerateParticles()
{
// Create particle and index arrays
if (Mode == BillboardMode.Cross) {
int crossBillboardNum = 2;
Vector3 z = Vector3.Zero;
particles = new ParticleVertex[ParticleNum * crossBillboardNum * 4];
indices = new int[ParticleNum * crossBillboardNum * 6];
int x = 0;
// For each billboard...
for (int i = 0; i < ParticleNum * 4 * crossBillboardNum; i += 4 * crossBillboardNum) {
//Vector3 pos = particlePositions[i / (4 * crossBillboardNum)];
Vector3 pos = Vector3.Zero;
Vector3 offsetX = new Vector3(ParticleSize.X / 2.0f,
ParticleSize.Y / 2.0f, 0);
Vector3 offsetZ = new Vector3(0, offsetX.Y, offsetX.X);
// Add 4 vertices per rectangle
particles[i + 0] = new ParticleVertex(pos +
new Vector3(-1, 1, 0) * offsetX, new Vector2(0, 0), z, 0, -1);
particles[i + 1] = new ParticleVertex(pos +
new Vector3(-1, -1, 0) * offsetX, new Vector2(0, 1), z, 0, -1);
particles[i + 2] = new ParticleVertex(pos +
new Vector3(1, -1, 0) * offsetX, new Vector2(1, 1), z, 0, -1);
particles[i + 3] = new ParticleVertex(pos +
new Vector3(1, 1, 0) * offsetX, new Vector2(1, 0), z, 0, -1);
particles[i + 4] = new ParticleVertex(pos +
new Vector3(0, 1, -1) * offsetZ, new Vector2(0, 0), z, 0, -1);
particles[i + 5] = new ParticleVertex(pos +
new Vector3(0, -1, -1) * offsetZ, new Vector2(0, 1), z, 0, -1);
particles[i + 6] = new ParticleVertex(pos +
new Vector3(0, -1, 1) * offsetZ, new Vector2(1, 1), z, 0, -1);
particles[i + 7] = new ParticleVertex(pos +
new Vector3(0, 1, 1) * offsetZ, new Vector2(1, 0), z, 0, -1);
// Add 6 indices per rectangle to form four triangles
indices[x++] = i + 0;
indices[x++] = i + 3;
indices[x++] = i + 2;
indices[x++] = i + 2;
indices[x++] = i + 1;
indices[x++] = i + 0;
indices[x++] = i + 0 + 4;
indices[x++] = i + 3 + 4;
indices[x++] = i + 2 + 4;
indices[x++] = i + 2 + 4;
indices[x++] = i + 1 + 4;
indices[x++] = i + 0 + 4;
}
} else {
particles = new ParticleVertex[ParticleNum * 4];
indices = new int[ParticleNum * 6];
Vector3 z = Vector3.Zero;
int x = 0;
// Initialize particle settings and fill index and vertex arrays
for (int i = 0; i < ParticleNum * 4; i += 4) {
particles[i + 0] = new ParticleVertex(z, new Vector2(0, 0), z, 0, -1, 0, z);
particles[i + 1] = new ParticleVertex(z, new Vector2(0, 1), z, 0, -1, 0, z);
particles[i + 2] = new ParticleVertex(z, new Vector2(1, 1), z, 0, -1, 0, z);
particles[i + 3] = new ParticleVertex(z, new Vector2(1, 0), z, 0, -1, 0, z);
indices[x++] = i + 0;
indices[x++] = i + 3;
indices[x++] = i + 2;
indices[x++] = i + 2;
indices[x++] = i + 1;
indices[x++] = i + 0;
}
}
}
void GenerateParticles(Vector3[] particlePositions)
{
// Create vertex and index arrays
particles = new ParticleVertex[nBillboards * 4];
indices = new int[nBillboards * 6];
int x = 0;
Vector3 z = Vector3.Zero;
// For each billboard...
for (int i = 0; i < nBillboards * 4; i += 4) {
Vector3 pos = particlePositions[i / 4];
// Add 4 vertices at the billboard's position
particles[i + 0] = new ParticleVertex(pos, new Vector2(0, 0), z, 0, -1, 0, End);
particles[i + 1] = new ParticleVertex(pos, new Vector2(0, 1), z, 0, -1, 0, End);
particles[i + 2] = new ParticleVertex(pos, new Vector2(1, 1), z, 0, -1, 0, End);
particles[i + 3] = new ParticleVertex(pos, new Vector2(1, 0), z, 0, -1, 0, End);
// Add 6 indices to form two triangles
indices[x++] = i + 0;
indices[x++] = i + 3;
indices[x++] = i + 2;
indices[x++] = i + 2;
indices[x++] = i + 1;
indices[x++] = i + 0;
}
// Create and set the vertex buffer
vertexBuffers = new VertexBuffer(graphicsDevice,
typeof(ParticleVertex),
nBillboards * 4, BufferUsage.WriteOnly);
vertexBuffers.SetData<ParticleVertex>(particles);
// Create and set the index buffer
indexBuffers = new IndexBuffer(graphicsDevice,
IndexElementSize.ThirtyTwoBits,
nBillboards * 6, BufferUsage.WriteOnly);
indexBuffers.SetData<int>(indices);
}