/// <summary>
/// Constructs the ribbon by outputting vertex stream based on the positions and sizes specified previously
/// </summary>
/// <param name="bufferState">Target <see cref="ParticleBufferState"/></param> to use
/// <param name="invViewX">Unit vector X in clip space as calculated from the inverse view matrix</param>
/// <param name="invViewY">Unit vector Y in clip space as calculated from the inverse view matrix</param>
/// <param name="quadsPerParticle">The required number of quads per each particle</param>
public unsafe void Ribbonize(ref ParticleBufferState bufferState, Vector3 invViewX, Vector3 invViewY, int quadsPerParticle)
{
if (lastParticle <= 0)
{
return;
}
var posAttribute = bufferState.GetAccessor(VertexAttributes.Position);
var texAttribute = bufferState.GetAccessor(bufferState.DefaultTexCoords);
if (lastParticle <= sections)
{
// Optional - connect first particle to the origin/emitter
// Draw a dummy quad for the first particle
var particlePos = new Vector3(0, 0, 0);
var uvCoord = new Vector2(0, 0);
for (var particleIdx = 0; particleIdx < lastParticle; particleIdx++)
{
for (var vtxIdx = 0; vtxIdx < 4; vtxIdx++)
{
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
}
}
return;
}
if (sections > 1)
{
if (SmoothingPolicy == SmoothingPolicy.Best)
{
ExpandVertices_Circular();
}
else // if (SmoothingPolicy == SmoothingPolicy.Fast)
{
ExpandVertices_CatmullRom();
}
}
bufferState.SetVerticesPerSegment(quadsPerParticle * 6, quadsPerParticle * 4, quadsPerParticle * 2);
var positions = (Vector3 *)positionData;
var sizes = (float *)sizeData;
// Step 1 - Determine the origin of the ribbon
var invViewZ = Vector3.Cross(invViewX, invViewY);
invViewZ.Normalize();
var axis0 = positions[0] - positions[1];
axis0.Normalize();
var oldPoint = positions[0];
var oldUnitX = GetWidthVector(sizes[0], ref invViewZ, ref axis0, ref axis0);
// Step 2 - Draw each particle, connecting it to the previous (front) position
var vCoordOld = 0f;
for (int i = 0; i < lastParticle; i++)
{
var centralPos = positions[i];
var particleSize = sizes[i];
// Directions for smoothing
var axis1 = (i + 1 < lastParticle) ? positions[i] - positions[i + 1] : positions[lastParticle - 2] - positions[lastParticle - 1];
axis1.Normalize();
var unitX = GetWidthVector(particleSize, ref invViewZ, ref axis0, ref axis1);
axis0 = axis1;
// Particle rotation - intentionally IGNORED for ribbon
var particlePos = oldPoint - oldUnitX;
var uvCoord = new Vector2(0, 0);
var rotatedCoord = uvCoord;
// Top Left - 0f 0f
uvCoord.Y = (TextureCoordinatePolicy == TextureCoordinatePolicy.AsIs) ? 0 : vCoordOld;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
rotatedCoord = UVRotate.GetCoords(uvCoord);
bufferState.SetAttribute(texAttribute, (IntPtr)(&rotatedCoord));
bufferState.NextVertex();
// Top Right - 1f 0f
particlePos += oldUnitX * 2;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
uvCoord.X = 1;
rotatedCoord = UVRotate.GetCoords(uvCoord);
bufferState.SetAttribute(texAttribute, (IntPtr)(&rotatedCoord));
bufferState.NextVertex();
// Move the position to the next particle in the ribbon
particlePos += centralPos - oldPoint;
particlePos += unitX - oldUnitX;
vCoordOld = (TextureCoordinatePolicy == TextureCoordinatePolicy.Stretched) ?
((i + 1) / (float)(lastParticle) * TexCoordsFactor) : ((centralPos - oldPoint).Length() * TexCoordsFactor) + vCoordOld;
// Bottom Left - 1f 1f
uvCoord.Y = (TextureCoordinatePolicy == TextureCoordinatePolicy.AsIs) ? 1 : vCoordOld;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
rotatedCoord = UVRotate.GetCoords(uvCoord);
bufferState.SetAttribute(texAttribute, (IntPtr)(&rotatedCoord));
bufferState.NextVertex();
// Bottom Right - 0f 1f
particlePos -= unitX * 2;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
uvCoord.X = 0;
rotatedCoord = UVRotate.GetCoords(uvCoord);
bufferState.SetAttribute(texAttribute, (IntPtr)(&rotatedCoord));
bufferState.NextVertex();
// Preserve the old attributes for the next cycle
oldUnitX = unitX;
oldPoint = centralPos;
}
}
/// <summary>
/// Constructs the ribbon by outputting vertex stream based on the positions and sizes specified previously
/// </summary>
/// <param name="bufferState">Target <see cref="ParticleBufferState"/></param> to use
/// <param name="invViewX">Unit vector X in clip space as calculated from the inverse view matrix</param>
/// <param name="invViewY">Unit vector Y in clip space as calculated from the inverse view matrix</param>
/// <param name="quadsPerParticle">The required number of quads per each particle</param>
public unsafe void Ribbonize(ref ParticleBufferState bufferState, Vector3 invViewX, Vector3 invViewY, int quadsPerParticle)
{
if (lastParticle <= 0)
return;
var posAttribute = bufferState.GetAccessor(VertexAttributes.Position);
var texAttribute = bufferState.GetAccessor(bufferState.DefaultTexCoords);
if (lastParticle <= sections)
{
// Optional - connect first particle to the origin/emitter
// Draw a dummy quad for the first particle
var particlePos = new Vector3(0, 0, 0);
var uvCoord = new Vector2(0, 0);
for (var particleIdx = 0; particleIdx < lastParticle; particleIdx++)
{
for (var vtxIdx = 0; vtxIdx < 4; vtxIdx++)
{
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
}
}
return;
}
if (sections > 1)
{
if (SmoothingPolicy == SmoothingPolicy.Best)
ExpandVertices_Circular();
else // if (SmoothingPolicy == SmoothingPolicy.Fast)
ExpandVertices_CatmullRom();
}
bufferState.SetVerticesPerSegment(quadsPerParticle * 6, quadsPerParticle * 4, quadsPerParticle * 2);
var positions = (Vector3*)positionData;
var sizes = (float*)sizeData;
// Step 1 - Determine the origin of the ribbon
var invViewZ = Vector3.Cross(invViewX, invViewY);
invViewZ.Normalize();
var axis0 = positions[0] - positions[1];
axis0.Normalize();
var oldPoint = positions[0];
var oldUnitX = GetWidthVector(sizes[0], ref invViewZ, ref axis0, ref axis0);
// Step 2 - Draw each particle, connecting it to the previous (front) position
var vCoordOld = 0f;
for (int i = 0; i < lastParticle; i++)
{
var centralPos = positions[i];
var particleSize = sizes[i];
// Directions for smoothing
var axis1 = (i + 1 < lastParticle) ? positions[i] - positions[i + 1] : positions[lastParticle - 2] - positions[lastParticle - 1];
axis1.Normalize();
var unitX = GetWidthVector(particleSize, ref invViewZ, ref axis0, ref axis1);
axis0 = axis1;
// Particle rotation - intentionally IGNORED for ribbon
var particlePos = oldPoint - oldUnitX;
var uvCoord = new Vector2(0, 0);
var rotatedCoord = uvCoord;
// Top Left - 0f 0f
uvCoord.Y = (TextureCoordinatePolicy == TextureCoordinatePolicy.AsIs) ? 0 : vCoordOld;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
rotatedCoord = UVRotate.GetCoords(uvCoord);
bufferState.SetAttribute(texAttribute, (IntPtr)(&rotatedCoord));
bufferState.NextVertex();
// Top Right - 1f 0f
particlePos += oldUnitX * 2;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
uvCoord.X = 1;
rotatedCoord = UVRotate.GetCoords(uvCoord);
bufferState.SetAttribute(texAttribute, (IntPtr)(&rotatedCoord));
bufferState.NextVertex();
// Move the position to the next particle in the ribbon
particlePos += centralPos - oldPoint;
particlePos += unitX - oldUnitX;
vCoordOld = (TextureCoordinatePolicy == TextureCoordinatePolicy.Stretched) ?
((i + 1)/(float)(lastParticle) * TexCoordsFactor) : ((centralPos - oldPoint).Length() * TexCoordsFactor) + vCoordOld;
// Bottom Left - 1f 1f
uvCoord.Y = (TextureCoordinatePolicy == TextureCoordinatePolicy.AsIs) ? 1 : vCoordOld;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
rotatedCoord = UVRotate.GetCoords(uvCoord);
bufferState.SetAttribute(texAttribute, (IntPtr)(&rotatedCoord));
bufferState.NextVertex();
// Bottom Right - 0f 1f
particlePos -= unitX * 2;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
uvCoord.X = 0;
rotatedCoord = UVRotate.GetCoords(uvCoord);
bufferState.SetAttribute(texAttribute, (IntPtr)(&rotatedCoord));
bufferState.NextVertex();
// Preserve the old attributes for the next cycle
oldUnitX = unitX;
oldPoint = centralPos;
}
}