public void CalculateStartPosition(float elapsedTime, Matrix worldMatrix, float userScale, out Vector3 startOffset, out Vector3 startPosition)
{
Vector3 currentOffsetUntransformed;
Offset.GetInterpolatedValue <Vector3>(elapsedTime, out currentOffsetUntransformed);
float currentSize;
Size.GetInterpolatedValue <float>(elapsedTime, out currentSize);
currentSize *= MyMwcUtils.GetRandomFloat(RadiusMin, RadiusMax) * userScale;
Vector3 localPos = Vector3.Zero;
Vector3 worldOffset;
Vector3.Transform(ref currentOffsetUntransformed, ref worldMatrix, out worldOffset);
switch (Type)
{
case MyParticleEmitterType.Point:
localPos = Vector3.Zero;
break;
case MyParticleEmitterType.Line:
localPos = Vector3.Forward * MyMwcUtils.GetRandomFloat(0.0f, currentSize);
break;
case MyParticleEmitterType.Sphere:
localPos = MyMwcUtils.GetRandomVector3Normalized() * currentSize;
break;
case MyParticleEmitterType.Box:
float currentSizeHalf = currentSize * 0.5f;
localPos =
new Vector3(
MinerWars.CommonLIB.AppCode.Utils.MyMwcUtils.GetRandomFloat(-currentSizeHalf, currentSizeHalf),
MinerWars.CommonLIB.AppCode.Utils.MyMwcUtils.GetRandomFloat(-currentSizeHalf, currentSizeHalf),
MinerWars.CommonLIB.AppCode.Utils.MyMwcUtils.GetRandomFloat(-currentSizeHalf, currentSizeHalf)
);
break;
case MyParticleEmitterType.Hemisphere:
localPos = MyMwcUtils.GetRandomVector3HemisphereNormalized(Vector3.Forward) * currentSize;
break;
case MyParticleEmitterType.Circle:
localPos = MyMwcUtils.GetRandomVector3CircleNormalized() * currentSize;
break;
default:
System.Diagnostics.Debug.Assert(false);
break;
}
Vector3 worldPos;
if (DirToCamera)
{
Matrix WorldView = worldMatrix * MyCamera.ViewMatrix;
WorldView.Translation += currentOffsetUntransformed;
Matrix newWorld = WorldView * Matrix.Invert(MyCamera.ViewMatrix);
Vector3 dir = MyCamera.Position - newWorld.Translation;
dir.Normalize();
Matrix matrix = MyMath.MatrixFromDir(dir);
matrix.Translation = newWorld.Translation;
Vector3.Transform(ref localPos, ref matrix, out worldPos);
startOffset = newWorld.Translation;
startPosition = worldPos;
}
else
{
Vector3.TransformNormal(ref localPos, ref worldMatrix, out worldPos);
startOffset = worldOffset;
startPosition = worldOffset + worldPos;
}
}