protected override void OnDrawBillboard(ref BillboardArgs b, PackedTexture texture, VertexPositionColorTexture[] vertices, int index)
{
#region ----- Billboarding -----
// The billboard orientation is defined by three vectors: normal (pointing to the camera),
// up and right (both lying in the billboard plane).
// normal and up are given. right is computed using the cross product up x normal.
// normal and up should be perpendicular, but usually they are not. Therefore, one vector
// must be corrected. For spherical billboards, the normal is fixed and the up vector
// is corrected. For cylindrical billboards (= axial billboards), the up vector is fixed
// and the b.Normal is corrected.
// Normal
if (b.Orientation.Normal == BillboardNormal.ViewpointOriented)
{
Vector3F normal = _cameraPose.Position - b.Position;
if (normal.TryNormalize())
{
b.Normal = normal;
}
}
// Axis = up vector
if (b.Orientation.IsAxisInViewSpace)
{
b.Axis = _cameraPose.ToWorldDirection(b.Axis);
}
if (1 - Vector3F.Dot(b.Normal, b.Axis) < Numeric.EpsilonF)
{
// Normal and axis are parallel.
// --> Bend normal by adding a fraction of the camera down vector.
b.Normal += _cameraDown * 0.001f;
b.Normal.Normalize();
}
// Compute right.
//Vector3F right = Vector3F.Cross(b.Axis, b.Normal);
// Inlined:
Vector3F right;
right.X = b.Axis.Y * b.Normal.Z - b.Axis.Z * b.Normal.Y;
right.Y = b.Axis.Z * b.Normal.X - b.Axis.X * b.Normal.Z;
right.Z = b.Axis.X * b.Normal.Y - b.Axis.Y * b.Normal.X;
if (!right.TryNormalize())
{
right = b.Normal.Orthonormal1; // Normal and axis are parallel --> Choose random perpendicular vector.
}
if (b.Orientation.IsAxisFixed)
{
// Make sure normal is perpendicular to right and up.
//normal = Vector3F.Cross(right, b.Axis);
// Inlined:
b.Normal.X = right.Y * b.Axis.Z - right.Z * b.Axis.Y;
b.Normal.Y = right.Z * b.Axis.X - right.X * b.Axis.Z;
b.Normal.Z = right.X * b.Axis.Y - right.Y * b.Axis.X;
// No need to normalize because right and up are normalized and perpendicular.
}
else
{
// Make sure axis is perpendicular to normal and right.
//b.Axis = Vector3F.Cross(b.Normal, right);
// Inlined:
b.Axis.X = b.Normal.Y * right.Z - b.Normal.Z * right.Y;
b.Axis.Y = b.Normal.Z * right.X - b.Normal.X * right.Z;
b.Axis.Z = b.Normal.X * right.Y - b.Normal.Y * right.X;
// No need to normalize because normal and right are normalized and perpendicular.
}
#endregion
#region ----- Rotate up and right vectors -----
Vector3F upRotated;
Vector3F rightRotated;
if (b.Angle != 0.0f)
{
// Rotate up and right.
// Here is the readable code.
//Matrix33F rotation = Matrix33F.CreateRotation(b.Normal, b.Angle);
//Vector3F upRotated = rotation * b.Axis;
//Vector3F rightRotated = rotation * right;
// Inlined code:
float x = b.Normal.X;
float y = b.Normal.Y;
float z = b.Normal.Z;
float x2 = x * x;
float y2 = y * y;
float z2 = z * z;
float xy = x * y;
float xz = x * z;
float yz = y * z;
float cos = (float)Math.Cos(b.Angle);
float sin = (float)Math.Sin(b.Angle);
float xsin = x * sin;
float ysin = y * sin;
float zsin = z * sin;
float oneMinusCos = 1.0f - cos;
float m00 = x2 + cos * (1.0f - x2);
float m01 = xy * oneMinusCos - zsin;
float m02 = xz * oneMinusCos + ysin;
float m10 = xy * oneMinusCos + zsin;
float m11 = y2 + cos * (1.0f - y2);
float m12 = yz * oneMinusCos - xsin;
float m20 = xz * oneMinusCos - ysin;
float m21 = yz * oneMinusCos + xsin;
float m22 = z2 + cos * (1.0f - z2);
upRotated.X = m00 * b.Axis.X + m01 * b.Axis.Y + m02 * b.Axis.Z;
upRotated.Y = m10 * b.Axis.X + m11 * b.Axis.Y + m12 * b.Axis.Z;
upRotated.Z = m20 * b.Axis.X + m21 * b.Axis.Y + m22 * b.Axis.Z;
rightRotated.X = m00 * right.X + m01 * right.Y + m02 * right.Z;
rightRotated.Y = m10 * right.X + m11 * right.Y + m12 * right.Z;
rightRotated.Z = m20 * right.X + m21 * right.Y + m22 * right.Z;
}
else
{
// Angle is 0 - no rotation.
upRotated = b.Axis;
rightRotated = right;
}
#endregion
#region ----- Handle texture information and size -----
Vector2F texCoordTopLeft = texture.GetTextureCoordinates(Vector2F.Zero, b.AnimationTime);
Vector2F texCoordBottomRight = texture.GetTextureCoordinates(Vector2F.One, b.AnimationTime);
// Handle mirroring.
if (b.Size.X < 0)
{
b.Size.X = -b.Size.X;
MathHelper.Swap(ref texCoordTopLeft.X, ref texCoordBottomRight.X);
}
if (b.Size.Y < 0)
{
b.Size.Y = -b.Size.Y;
MathHelper.Swap(ref texCoordTopLeft.Y, ref texCoordBottomRight.Y);
}
b.Size.X /= 2.0f;
b.Size.Y /= 2.0f;
// Offset from billboard center to right edge.
Vector3F hOffset;
hOffset.X = rightRotated.X * b.Size.X;
hOffset.Y = rightRotated.Y * b.Size.X;
hOffset.Z = rightRotated.Z * b.Size.X;
// Offset from reference point to top edge.
Vector3F vOffset;
vOffset.X = upRotated.X * b.Size.Y;
vOffset.Y = upRotated.Y * b.Size.Y;
vOffset.Z = upRotated.Z * b.Size.Y;
#endregion
#region ----- Get Color -----
// Premultiply alpha.
Vector4 color4 = new Vector4
{
X = b.Color.X * b.Alpha,
Y = b.Color.Y * b.Alpha,
Z = b.Color.Z * b.Alpha,
// Apply blend mode (0 = additive, 1 = alpha blend).
W = b.Alpha * b.BlendMode
};
var color = new Color(color4);
#endregion
#region ----- Initializes vertices in vertex array -----
// Bottom left vertex
vertices[index].Position.X = b.Position.X - hOffset.X - vOffset.X;
vertices[index].Position.Y = b.Position.Y - hOffset.Y - vOffset.Y;
vertices[index].Position.Z = b.Position.Z - hOffset.Z - vOffset.Z;
vertices[index].Color = color;
vertices[index].TextureCoordinate.X = texCoordTopLeft.X;
vertices[index].TextureCoordinate.Y = texCoordBottomRight.Y;
index++;
// Top left vertex
vertices[index].Position.X = b.Position.X - hOffset.X + vOffset.X;
vertices[index].Position.Y = b.Position.Y - hOffset.Y + vOffset.Y;
vertices[index].Position.Z = b.Position.Z - hOffset.Z + vOffset.Z;
vertices[index].Color = color;
vertices[index].TextureCoordinate.X = texCoordTopLeft.X;
vertices[index].TextureCoordinate.Y = texCoordTopLeft.Y;
index++;
// Top right vertex
vertices[index].Position.X = b.Position.X + hOffset.X + vOffset.X;
vertices[index].Position.Y = b.Position.Y + hOffset.Y + vOffset.Y;
vertices[index].Position.Z = b.Position.Z + hOffset.Z + vOffset.Z;
vertices[index].Color = color;
vertices[index].TextureCoordinate.X = texCoordBottomRight.X;
vertices[index].TextureCoordinate.Y = texCoordTopLeft.Y;
index++;
// Bottom right vertex
vertices[index].Position.X = b.Position.X + hOffset.X - vOffset.X;
vertices[index].Position.Y = b.Position.Y + hOffset.Y - vOffset.Y;
vertices[index].Position.Z = b.Position.Z + hOffset.Z - vOffset.Z;
vertices[index].Color = color;
vertices[index].TextureCoordinate.X = texCoordBottomRight.X;
vertices[index].TextureCoordinate.Y = texCoordBottomRight.Y;
#endregion
}
protected override void OnDrawRibbon(ref RibbonArgs p0, ref RibbonArgs p1, PackedTexture texture, VertexPositionColorTexture[] vertices, int index)
{
// p0 and p1 specify a segment of a particle ribbon.
// --+--------------+--
// p0 p1
// --+--------------+--
#region ----- Handle texture information and size -----
float animationTime = p0.AnimationTime;
Vector2F texCoordTopLeft = texture.GetTextureCoordinates(new Vector2F(p0.TextureCoordinateU, 0), animationTime);
Vector2F texCoordBottomRight = texture.GetTextureCoordinates(new Vector2F(p1.TextureCoordinateU, 1), animationTime);
// Negative sizes (mirroring) is not supported because this conflicts with the
// texture tiling on ribbons.
float size0 = Math.Abs(p0.Size) / 2;
float size1 = Math.Abs(p1.Size) / 2;
// Offset from particle center to upper edge.
Vector3F up0;
up0.X = p0.Axis.X * size0;
up0.Y = p0.Axis.Y * size0;
up0.Z = p0.Axis.Z * size0;
Vector3F up1;
up1.X = p1.Axis.X * size1;
up1.Y = p1.Axis.Y * size1;
up1.Z = p1.Axis.Z * size1;
#endregion
#region ----- Get Color -----
// Premultiply alpha.
Vector4 color4 = new Vector4
{
X = p0.Color.X * p0.Alpha,
Y = p0.Color.Y * p0.Alpha,
Z = p0.Color.Z * p0.Alpha,
// Apply blend mode (0 = additive, 1 = alpha blend).
W = p0.Alpha * p0.BlendMode
};
var color0 = new Color(color4);
color4 = new Vector4
{
X = p1.Color.X * p1.Alpha,
Y = p1.Color.Y * p1.Alpha,
Z = p1.Color.Z * p1.Alpha,
W = p1.Alpha * p1.BlendMode
};
var color1 = new Color(color4);
#endregion
#region ----- Initializes vertices in vertex array -----
// Bottom left vertex
vertices[index].Position.X = p0.Position.X - up0.X;
vertices[index].Position.Y = p0.Position.Y - up0.Y;
vertices[index].Position.Z = p0.Position.Z - up0.Z;
vertices[index].Color = color0;
vertices[index].TextureCoordinate.X = texCoordTopLeft.X;
vertices[index].TextureCoordinate.Y = texCoordBottomRight.Y;
index++;
// Top left vertex
vertices[index].Position.X = p0.Position.X + up0.X;
vertices[index].Position.Y = p0.Position.Y + up0.Y;
vertices[index].Position.Z = p0.Position.Z + up0.Z;
vertices[index].Color = color0;
vertices[index].TextureCoordinate.X = texCoordTopLeft.X;
vertices[index].TextureCoordinate.Y = texCoordTopLeft.Y;
index++;
// Top right vertex
vertices[index].Position.X = p1.Position.X + up1.X;
vertices[index].Position.Y = p1.Position.Y + up1.Y;
vertices[index].Position.Z = p1.Position.Z + up1.Z;
vertices[index].Color = color1;
vertices[index].TextureCoordinate.X = texCoordBottomRight.X;
vertices[index].TextureCoordinate.Y = texCoordTopLeft.Y;
index++;
// Bottom right vertex
vertices[index].Position.X = p1.Position.X - up1.X;
vertices[index].Position.Y = p1.Position.Y - up1.Y;
vertices[index].Position.Z = p1.Position.Z - up1.Z;
vertices[index].Color = color1;
vertices[index].TextureCoordinate.X = texCoordBottomRight.X;
vertices[index].TextureCoordinate.Y = texCoordBottomRight.Y;
#endregion
}
