/// <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;
}
}
/// <inheritdoc />
public override unsafe int BuildVertexBuffer(ref ParticleBufferState bufferState, Vector3 invViewX, Vector3 invViewY,
ref Vector3 spaceTranslation, ref Quaternion spaceRotation, float spaceScale, ref ParticleList sorter)
{
// Update the curve samplers if required
base.BuildVertexBuffer(ref bufferState, invViewX, invViewY, ref spaceTranslation, ref spaceRotation, spaceScale, ref sorter);
// Get all required particle fields
var positionField = sorter.GetField(ParticleFields.Position);
if (!positionField.IsValid())
return 0;
var sizeField = sorter.GetField(ParticleFields.Size);
var lifeField = sorter.GetField(ParticleFields.Life);
var angleField = sorter.GetField(ParticleFields.Angle);
var hasAngle = angleField.IsValid() || (SamplerRotation != null);
// Check if the draw space is identity - in this case we don't need to transform the position, scale and rotation vectors
var trsIdentity = (spaceScale == 1f);
trsIdentity = trsIdentity && (spaceTranslation.Equals(new Vector3(0, 0, 0)));
trsIdentity = trsIdentity && (spaceRotation.Equals(Quaternion.Identity));
var renderedParticles = 0;
var posAttribute = bufferState.GetAccessor(VertexAttributes.Position);
var texAttribute = bufferState.GetAccessor(bufferState.DefaultTexCoords);
foreach (var particle in sorter)
{
var centralPos = GetParticlePosition(particle, positionField, lifeField);
var particleSize = GetParticleSize(particle, sizeField, lifeField);
if (!trsIdentity)
{
spaceRotation.Rotate(ref centralPos);
centralPos = centralPos * spaceScale + spaceTranslation;
particleSize *= spaceScale;
}
// Use half size to make a Size = 1 result in a Billboard of 1m x 1m
var unitX = invViewX * (particleSize * 0.5f);
var unitY = invViewY * (particleSize * 0.5f);
// Particle rotation. Positive value means clockwise rotation.
if (hasAngle)
{
var rotationAngle = GetParticleRotation(particle, angleField, lifeField);
var cosA = (float)Math.Cos(rotationAngle);
var sinA = (float)Math.Sin(rotationAngle);
var tempX = unitX * cosA - unitY * sinA;
unitY = unitY * cosA + unitX * sinA;
unitX = tempX;
}
// vertex.Size = particleSize;
const float Sqrt3Half = 0.86602540378f;
unitY *= Sqrt3Half;
var halfX = unitX * 0.5f;
var particlePos = centralPos - halfX + unitY;
var uvCoord = new Vector2(0.25f, 0.5f - Sqrt3Half * 0.5f);
// Upper half
// 0f 0f
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 0f
particlePos += unitX;
uvCoord.X = 0.75f;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 1f
particlePos += halfX;
particlePos -= unitY;
uvCoord.X = 1;
uvCoord.Y = 0.5f;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 0f 1f
particlePos -= unitX * 2;
uvCoord.X = 0;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// Upper half
// 0f 0f
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 0f
particlePos += unitX * 2;
uvCoord.X = 1;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 1f
particlePos -= halfX;
particlePos -= unitY;
uvCoord.X = 0.75f;
uvCoord.Y = 1;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 0f 1f
particlePos -= unitX;
uvCoord.X = 0.25f;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
renderedParticles++;
}
var vtxPerShape = 4 * QuadsPerParticle;
return renderedParticles * vtxPerShape;
}
/// <inheritdoc />
public unsafe override int BuildVertexBuffer(ref ParticleBufferState bufferState, Vector3 invViewX, Vector3 invViewY,
ref Vector3 spaceTranslation, ref Quaternion spaceRotation, float spaceScale, ref ParticleList sorter)
{
// Update the curve samplers if required
base.BuildVertexBuffer(ref bufferState, invViewX, invViewY, ref spaceTranslation, ref spaceRotation, spaceScale, ref sorter);
// Get all required particle fields
var positionField = sorter.GetField(ParticleFields.Position);
if (!positionField.IsValid())
return 0;
var lifeField = sorter.GetField(ParticleFields.Life);
var sizeField = sorter.GetField(ParticleFields.Size);
var rotField = sorter.GetField(ParticleFields.Quaternion);
var hasRotation = rotField.IsValid() || (SamplerRotation != null);
// Check if the draw space is identity - in this case we don't need to transform the position, scale and rotation vectors
var trsIdentity = (spaceScale == 1f);
trsIdentity = trsIdentity && (spaceTranslation.Equals(new Vector3(0, 0, 0)));
trsIdentity = trsIdentity && (spaceRotation.Equals(Quaternion.Identity));
var renderedParticles = 0;
var posAttribute = bufferState.GetAccessor(VertexAttributes.Position);
var texAttribute = bufferState.GetAccessor(bufferState.DefaultTexCoords);
foreach (var particle in sorter)
{
var centralPos = GetParticlePosition(particle, positionField, lifeField);
var particleSize = GetParticleSize(particle, sizeField, lifeField);
var unitX = new Vector3(1, 0, 0);
var unitY = new Vector3(0, 0, 1);
if (hasRotation)
{
var particleRotation = GetParticleRotation(particle, rotField, lifeField);
particleRotation.Rotate(ref unitX);
particleRotation.Rotate(ref unitY);
}
// The TRS matrix is not an identity, so we need to transform the quad
if (!trsIdentity)
{
spaceRotation.Rotate(ref centralPos);
centralPos = centralPos * spaceScale + spaceTranslation;
particleSize *= spaceScale;
spaceRotation.Rotate(ref unitX);
spaceRotation.Rotate(ref unitY);
}
// Use half size to make a Size = 1 result in a Billboard of 1m x 1m
unitX *= (particleSize * 0.5f);
unitY *= (particleSize * 0.5f);
var particlePos = centralPos - unitX + unitY;
var uvCoord = new Vector2(0, 0);
// 0f 0f
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 0f
particlePos += unitX * 2;
uvCoord.X = 1;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 1f
particlePos -= unitY * 2;
uvCoord.Y = 1;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 0f 1f
particlePos -= unitX * 2;
uvCoord.X = 0;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
renderedParticles++;
}
var vtxPerShape = 4 * QuadsPerParticle;
return renderedParticles * vtxPerShape;
}
/// <inheritdoc />
public unsafe override int BuildVertexBuffer(ref ParticleBufferState bufferState, Vector3 invViewX, Vector3 invViewY,
ref Vector3 spaceTranslation, ref Quaternion spaceRotation, float spaceScale, ref ParticleList sorter)
{
// Update the curve samplers if required
base.BuildVertexBuffer(ref bufferState, invViewX, invViewY, ref spaceTranslation, ref spaceRotation, spaceScale, ref sorter);
// Get all the required particle fields
var positionField = sorter.GetField(ParticleFields.Position);
if (!positionField.IsValid())
return 0;
var lifeField = sorter.GetField(ParticleFields.Life);
var sizeField = sorter.GetField(ParticleFields.Size);
var directionField = sorter.GetField(ParticleFields.Direction);
// Check if the draw space is identity - in this case we don't need to transform the position, scale and rotation vectors
var trsIdentity = (spaceScale == 1f);
trsIdentity = trsIdentity && (spaceTranslation.Equals(new Vector3(0, 0, 0)));
trsIdentity = trsIdentity && (spaceRotation.Equals(Quaternion.Identity));
var renderedParticles = 0;
var posAttribute = bufferState.GetAccessor(VertexAttributes.Position);
var texAttribute = bufferState.GetAccessor(bufferState.DefaultTexCoords);
Vector3 invViewZ;
Vector3.Cross(ref invViewX, ref invViewY, out invViewZ);
invViewZ.Normalize();
foreach (var particle in sorter)
{
var centralPos = GetParticlePosition(particle, positionField, lifeField);
var centralOffset = (directionField.IsValid()) ? particle.Get(directionField) : new Vector3(0, 1, 0);
var particleSize = GetParticleSize(particle, sizeField, lifeField);
if (!trsIdentity)
{
spaceRotation.Rotate(ref centralPos);
centralPos = centralPos * spaceScale + spaceTranslation;
spaceRotation.Rotate(ref centralOffset);
centralOffset = centralOffset * spaceScale;
particleSize *= spaceScale;
}
var unitX = invViewX;
var unitY = invViewY;
{
var centralAxis = centralOffset;
float dotZ;
Vector3.Dot(ref centralAxis, ref invViewZ, out dotZ);
centralAxis -= invViewZ*dotZ;
centralAxis.Normalize();
float dotX;
Vector3.Dot(ref centralAxis, ref unitX, out dotX);
float dotY;
Vector3.Dot(ref centralAxis, ref unitY, out dotY);
unitX = unitX*dotY - unitY*dotX;
unitX.Normalize();
unitY = centralOffset;
}
// Use half size to make a Size = 1 result in a Billboard of 1m x 1m
unitX *= (particleSize * 0.5f);
if (ScaleLength)
{
unitY *= (LengthFactor * particleSize * 0.5f);
}
else
{
unitY *= (LengthFactor * 0.5f);
}
var particlePos = centralPos - unitX + unitY;
var uvCoord = new Vector2(0, 0);
// 0f 0f
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 0f
particlePos += unitX * 2;
uvCoord.X = 1;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 1f
particlePos -= unitY * 2;
uvCoord.Y = 1;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 0f 1f
particlePos -= unitX * 2;
uvCoord.X = 0;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
renderedParticles++;
}
var vtxPerShape = 4 * QuadsPerParticle;
return renderedParticles * vtxPerShape;
}
/// <inheritdoc />
public override unsafe int BuildVertexBuffer(ref ParticleBufferState bufferState, Vector3 invViewX, Vector3 invViewY,
ref Vector3 spaceTranslation, ref Quaternion spaceRotation, float spaceScale, ref ParticleList sorter)
{
// Step 1 - get all required fields to build the particle shapes. Some fields may not exist if no initializer or updater operates on them
// In that case we just decide on a default value for that field and skip the update
var positionField = sorter.GetField(ParticleFields.Position);
if (!positionField.IsValid())
return 0; // We can't display the particles without position. All other fields are optional
var sizeField = sorter.GetField(ParticleFields.Size);
var angleField = sorter.GetField(ParticleFields.Angle);
var hasAngle = angleField.IsValid();
var rectField = sorter.GetField(CustomParticleFields.RectangleXY);
var isRectangle = rectField.IsValid();
// In case of Local space particles they are simulated in local emitter space, but drawn in world space
// If the draw space is identity (i.e. simulation space = draw space) skip transforming the particle's location later
var trsIdentity = (spaceScale == 1f);
trsIdentity = trsIdentity && (spaceTranslation.Equals(new Vector3(0, 0, 0)));
trsIdentity = trsIdentity && (spaceRotation.Equals(new Quaternion(0, 0, 0, 1)));
// Custom feature - fix the Y axis to always point up in world space rather than screen space
if (FixYAxis)
{
invViewY = new Vector3(0, 1, 0);
invViewX.Y = 0;
invViewX.Normalize();
}
var renderedParticles = 0;
var posAttribute = bufferState.GetAccessor(VertexAttributes.Position);
var texAttribute = bufferState.GetAccessor(bufferState.DefaultTexCoords);
foreach (var particle in sorter)
{
var centralPos = particle.Get(positionField);
var particleSize = sizeField.IsValid() ? particle.Get(sizeField) : 1f;
if (!trsIdentity)
{
spaceRotation.Rotate(ref centralPos);
centralPos = centralPos * spaceScale + spaceTranslation;
particleSize *= spaceScale;
}
var unitX = invViewX * particleSize;
var unitY = invViewY * particleSize;
if (isRectangle)
{
var rectSize = particle.Get(rectField);
unitX *= rectSize.X;
unitY *= rectSize.Y;
}
// Particle rotation. Positive value means clockwise rotation.
if (hasAngle)
{
var rotationAngle = particle.Get(angleField);
var cosA = (float)Math.Cos(rotationAngle);
var sinA = (float)Math.Sin(rotationAngle);
var tempX = unitX * cosA - unitY * sinA;
unitY = unitY * cosA + unitX * sinA;
unitX = tempX;
}
var particlePos = centralPos - unitX + unitY;
var uvCoord = new Vector2(0, 0);
// 0f 0f
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 0f
particlePos += unitX * 2;
uvCoord.X = 1;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 1f 1f
particlePos -= unitY * 2;
uvCoord.Y = 1;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
// 0f 1f
particlePos -= unitX * 2;
uvCoord.X = 0;
bufferState.SetAttribute(posAttribute, (IntPtr)(&particlePos));
bufferState.SetAttribute(texAttribute, (IntPtr)(&uvCoord));
bufferState.NextVertex();
renderedParticles++;
}
// Return the number of updated vertices
var vtxPerShape = 4 * QuadsPerParticle;
return renderedParticles * vtxPerShape;
}
/// <summary>
/// Constructs the ribbon by outputting vertex stream based on the positions and sizes specified previously
/// </summary>
/// <param name="vtxBuilder">Target <see cref="ParticleVertexBuilder"/></param> to use
/// <param name="quadsPerParticle">The required number of quads per each particle</param>
public unsafe void Ribbonize(ref ParticleBufferState bufferState, 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();
}
}
var positions = (Vector3 *)positionData;
var directions = (Vector3 *)directionData;
bufferState.SetVerticesPerSegment(quadsPerParticle * 6, quadsPerParticle * 4, quadsPerParticle * 2);
var axis0 = positions[0] - positions[1];
axis0.Normalize();
var oldPoint = positions[0];
var oldUnitX = directions[0];
// 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];
// Directions for smoothing
var axis1 = (i + 1 < lastParticle) ? positions[i] - positions[i + 1] : positions[lastParticle - 2] - positions[lastParticle - 1];
axis1.Normalize();
var unitX = directions[i];
// Particle rotation - intentionally IGNORED for ribbon
var particlePos = (EdgePolicy == EdgePolicy.Center) ? oldPoint - oldUnitX : oldPoint;
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 += (EdgePolicy == EdgePolicy.Center) ? oldUnitX * 2 : oldUnitX;
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 -= (EdgePolicy == EdgePolicy.Center) ? unitX * 2 : unitX;
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;
}
}
