/// <summary>
/// 发射粒子
/// </summary>
/// <param name="position">起始位置</param>
/// <param name="speed">速率</param>
/// <param name="size">起始半径</param>
/// <param name="life">生命周期</param>
public void SpawnParticle(Point3D position, double speed, double size, double life)
{
// 不能超过最大粒子数
if (this.particleList.Count > this.MaxParticleCount)
{
return;
}
// 建立粒子描述子
ParticleDescriptor3D p = new ParticleDescriptor3D
{
Position = position,
StartLife = life,
Life = life,
StartSize = size,
Size = size
};
// 根据速率构造速度向量
float x = 1.0f - (float)rand.NextDouble() * 2.0f;
float z = 1.0f - (float)rand.NextDouble() * 2.0f;
Vector3D v = new Vector3D(x, z, 0.0);
v.Normalize();
v *= ((float)rand.NextDouble() + 0.25f) * (float)speed;
p.Velocity = new Vector3D(v.X, v.Y, v.Z);
p.Decay = 1.0f;
// 添加到渲染列表
this.particleList.Add(p);
}
/// <summary>
/// 依照更新完的描述子渲染前端
/// </summary>
private void UpdateGeometry()
{
Point3DCollection positions = new Point3DCollection();
Int32Collection indices = new Int32Collection();
PointCollection texcoords = new PointCollection();
for (int i = 0; i < this.particleList.Count; ++i)
{
int positionIndex = i * 4;
ParticleDescriptor3D p = this.particleList[i];
Point3D p1 = new Point3D(p.Position.X, p.Position.Y, p.Position.Z);
Point3D p2 = new Point3D(p.Position.X, p.Position.Y + p.Size, p.Position.Z);
Point3D p3 = new Point3D(p.Position.X + p.Size, p.Position.Y + p.Size, p.Position.Z);
Point3D p4 = new Point3D(p.Position.X + p.Size, p.Position.Y, p.Position.Z);
positions.Add(p1);
positions.Add(p2);
positions.Add(p3);
positions.Add(p4);
texcoords.Add(renderDirectionT1);
texcoords.Add(renderDirectionT2);
texcoords.Add(renderDirectionT3);
texcoords.Add(renderDirectionT4);
indices.Add(positionIndex);
indices.Add(positionIndex + 2);
indices.Add(positionIndex + 1);
indices.Add(positionIndex);
indices.Add(positionIndex + 3);
indices.Add(positionIndex + 2);
}
((MeshGeometry3D)this.particleModel.Geometry).Positions = positions;
((MeshGeometry3D)this.particleModel.Geometry).TriangleIndices = indices;
((MeshGeometry3D)this.particleModel.Geometry).TextureCoordinates = texcoords;
}