private void UpdateVertices(ParticleBag particleBag, Matrix4x4 modelViewMatrix)
{
var particles = particleBag.LiveParticles;
// Create billboarding rotation (always facing camera)
Matrix4x4.Decompose(modelViewMatrix, out _, out Quaternion modelViewRotation, out _);
modelViewRotation = Quaternion.Inverse(modelViewRotation);
var billboardMatrix = Matrix4x4.CreateFromQuaternion(modelViewRotation);
// Update vertex buffer
EnsureSpaceForVertices(particleBag.Count * 4);
for (int i = 0; i < particleBag.Count; ++i)
{
// Positions
var modelMatrix = orientationType == 0
? particles[i].GetRotationMatrix() * billboardMatrix * particles[i].GetTransformationMatrix()
: particles[i].GetRotationMatrix() * particles[i].GetTransformationMatrix();
var tl = Vector4.Transform(new Vector4(-1, -1, 0, 1), modelMatrix);
var bl = Vector4.Transform(new Vector4(-1, 1, 0, 1), modelMatrix);
var br = Vector4.Transform(new Vector4(1, 1, 0, 1), modelMatrix);
var tr = Vector4.Transform(new Vector4(1, -1, 0, 1), modelMatrix);
int quadStart = i * VertexSize * 4;
rawVertices[quadStart + 0] = tl.X;
rawVertices[quadStart + 1] = tl.Y;
rawVertices[quadStart + 2] = tl.Z;
rawVertices[quadStart + (VertexSize * 1) + 0] = bl.X;
rawVertices[quadStart + (VertexSize * 1) + 1] = bl.Y;
rawVertices[quadStart + (VertexSize * 1) + 2] = bl.Z;
rawVertices[quadStart + (VertexSize * 2) + 0] = br.X;
rawVertices[quadStart + (VertexSize * 2) + 1] = br.Y;
rawVertices[quadStart + (VertexSize * 2) + 2] = br.Z;
rawVertices[quadStart + (VertexSize * 3) + 0] = tr.X;
rawVertices[quadStart + (VertexSize * 3) + 1] = tr.Y;
rawVertices[quadStart + (VertexSize * 3) + 2] = tr.Z;
// Colors
for (int j = 0; j < 4; ++j)
{
rawVertices[quadStart + (VertexSize * j) + 3] = particles[i].Color.X;
rawVertices[quadStart + (VertexSize * j) + 4] = particles[i].Color.Y;
rawVertices[quadStart + (VertexSize * j) + 5] = particles[i].Color.Z;
rawVertices[quadStart + (VertexSize * j) + 6] = particles[i].Alpha;
}
// UVs
if (spriteSheetData != null && spriteSheetData.Sequences.Length > 0 && spriteSheetData.Sequences[0].Frames.Length > 0)
{
var sequence = spriteSheetData.Sequences[particles[i].Sequence % spriteSheetData.Sequences.Length];
var particleTime = particles[i].ConstantLifetime - particles[i].Lifetime;
var frame = particleTime * sequence.FramesPerSecond * animationRate;
var currentFrame = sequence.Frames[(int)Math.Floor(frame) % sequence.Frames.Length];
// Lerp frame coords and size
var subFrameTime = frame % 1.0f;
var offset = (currentFrame.StartMins * (1 - subFrameTime)) + (currentFrame.EndMins * subFrameTime);
var scale = ((currentFrame.StartMaxs - currentFrame.StartMins) * (1 - subFrameTime))
+ ((currentFrame.EndMaxs - currentFrame.EndMins) * subFrameTime);
rawVertices[quadStart + (VertexSize * 0) + 7] = offset.X + (scale.X * 0);
rawVertices[quadStart + (VertexSize * 0) + 8] = offset.Y + (scale.Y * 1);
rawVertices[quadStart + (VertexSize * 1) + 7] = offset.X + (scale.X * 0);
rawVertices[quadStart + (VertexSize * 1) + 8] = offset.Y + (scale.Y * 0);
rawVertices[quadStart + (VertexSize * 2) + 7] = offset.X + (scale.X * 1);
rawVertices[quadStart + (VertexSize * 2) + 8] = offset.Y + (scale.Y * 0);
rawVertices[quadStart + (VertexSize * 3) + 7] = offset.X + (scale.X * 1);
rawVertices[quadStart + (VertexSize * 3) + 8] = offset.Y + (scale.Y * 1);
}
else
{
rawVertices[quadStart + (VertexSize * 0) + 7] = 0;
rawVertices[quadStart + (VertexSize * 0) + 8] = 1;
rawVertices[quadStart + (VertexSize * 1) + 7] = 0;
rawVertices[quadStart + (VertexSize * 1) + 8] = 0;
rawVertices[quadStart + (VertexSize * 2) + 7] = 1;
rawVertices[quadStart + (VertexSize * 2) + 8] = 0;
rawVertices[quadStart + (VertexSize * 3) + 7] = 1;
rawVertices[quadStart + (VertexSize * 3) + 8] = 1;
}
}
GL.BindBuffer(BufferTarget.ArrayBuffer, vertexBufferHandle);
GL.BufferData(BufferTarget.ArrayBuffer, particleBag.Count * VertexSize * 4 * sizeof(float), rawVertices, BufferUsageHint.DynamicDraw);
}
public void Render(ParticleBag particleBag, Matrix4x4 viewProjectionMatrix, Matrix4x4 modelViewMatrix)
{
if (particleBag.Count == 0)
{
return;
}
// Update vertex buffer
UpdateVertices(particleBag, modelViewMatrix);
// Draw it
GL.Enable(EnableCap.Blend);
GL.UseProgram(shader.Program);
if (additive)
{
GL.BlendFunc(BlendingFactor.SrcAlpha, BlendingFactor.One);
}
else
{
GL.BlendFunc(BlendingFactor.SrcAlpha, BlendingFactor.OneMinusSrcAlpha);
}
GL.BindVertexArray(quadVao);
GL.EnableVertexAttribArray(0);
GL.ActiveTexture(TextureUnit.Texture0);
GL.BindTexture(TextureTarget.Texture2D, glTexture);
GL.BindBuffer(BufferTarget.ArrayBuffer, vertexBufferHandle);
GL.Uniform1(shader.GetUniformLocation("uTexture"), 0); // set texture unit 0 as uTexture uniform
var otkProjection = viewProjectionMatrix.ToOpenTK();
GL.UniformMatrix4(shader.GetUniformLocation("uProjectionViewMatrix"), false, ref otkProjection);
// TODO: This formula is a guess but still seems too bright compared to valve particles
GL.Uniform1(shader.GetUniformLocation("uOverbrightFactor"), overbrightFactor);
GL.Disable(EnableCap.CullFace);
GL.Enable(EnableCap.DepthTest);
GL.DepthMask(false);
GL.BindBuffer(BufferTarget.ElementArrayBuffer, quadIndices.GLHandle);
GL.DrawElements(BeginMode.Triangles, particleBag.Count * 6, DrawElementsType.UnsignedShort, 0);
GL.BindBuffer(BufferTarget.ElementArrayBuffer, 0);
GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
GL.Enable(EnableCap.CullFace);
GL.Disable(EnableCap.DepthTest);
GL.DepthMask(true);
GL.BindVertexArray(0);
GL.UseProgram(0);
if (additive)
{
GL.BlendEquation(BlendEquationMode.FuncAdd);
}
GL.Disable(EnableCap.Blend);
}
public void Render(ParticleBag particleBag, Matrix4x4 viewProjectionMatrix, Matrix4x4 modelViewMatrix)
{
var particles = particleBag.LiveParticles;
GL.Enable(EnableCap.Blend);
GL.UseProgram(shader.Program);
if (additive)
{
GL.BlendFunc(BlendingFactor.SrcAlpha, BlendingFactor.One);
}
else
{
GL.BlendFunc(BlendingFactor.SrcAlpha, BlendingFactor.OneMinusSrcAlpha);
}
GL.BindVertexArray(quadVao);
GL.EnableVertexAttribArray(0);
GL.ActiveTexture(TextureUnit.Texture0);
GL.BindTexture(TextureTarget.Texture2D, glTexture);
GL.Uniform1(shader.GetUniformLocation("uTexture"), 0); // set texture unit 0 as uTexture uniform
var otkProjection = viewProjectionMatrix.ToOpenTK();
GL.UniformMatrix4(shader.GetUniformLocation("uProjectionViewMatrix"), false, ref otkProjection);
// TODO: This formula is a guess but still seems too bright compared to valve particles
GL.Uniform1(shader.GetUniformLocation("uOverbrightFactor"), overbrightFactor);
var modelMatrixLocation = shader.GetUniformLocation("uModelMatrix");
var colorLocation = shader.GetUniformLocation("uColor");
var alphaLocation = shader.GetUniformLocation("uAlpha");
var uvOffsetLocation = shader.GetUniformLocation("uUvOffset");
var uvScaleLocation = shader.GetUniformLocation("uUvScale");
// Create billboarding rotation (always facing camera)
Matrix4x4.Decompose(modelViewMatrix, out _, out Quaternion modelViewRotation, out _);
modelViewRotation = Quaternion.Inverse(modelViewRotation);
var billboardMatrix = Matrix4x4.CreateFromQuaternion(modelViewRotation);
for (int i = 0; i < particles.Length; ++i)
{
var position = new Vector3(particles[i].Position.X, particles[i].Position.Y, particles[i].Position.Z);
var previousPosition = new Vector3(particles[i].PositionPrevious.X, particles[i].PositionPrevious.Y, particles[i].PositionPrevious.Z);
var difference = previousPosition - position;
var direction = Vector3.Normalize(difference);
var midPoint = position + (0.5f * difference);
// Trail width = radius
// Trail length = distance between current and previous times trail length divided by 2 (because the base particle is 2 wide)
var length = Math.Min(maxLength, particles[i].TrailLength * difference.Length() / 2f);
var t = 1 - (particles[i].Lifetime / particles[i].ConstantLifetime);
var animatedLength = t >= lengthFadeInTime
? length
: t * length / lengthFadeInTime;
var scaleMatrix = Matrix4x4.CreateScale(particles[i].Radius, animatedLength, 1);
// Center the particle at the midpoint between the two points
var translationMatrix = Matrix4x4.CreateTranslation(Vector3.UnitY * animatedLength);
// Calculate rotation matrix
var axis = Vector3.Normalize(Vector3.Cross(Vector3.UnitY, direction));
var angle = (float)Math.Acos(direction.Y);
var rotationMatrix = Matrix4x4.CreateFromAxisAngle(axis, angle);
var modelMatrix =
orientationType == 0 ? Matrix4x4.Multiply(scaleMatrix, Matrix4x4.Multiply(translationMatrix, rotationMatrix))
: particles[i].GetTransformationMatrix();
// Position/Radius uniform
var otkModelMatrix = modelMatrix.ToOpenTK();
GL.UniformMatrix4(modelMatrixLocation, false, ref otkModelMatrix);
if (spriteSheetData != null && spriteSheetData.Sequences.Length > 0 && spriteSheetData.Sequences[0].Frames.Length > 0)
{
var sequence = spriteSheetData.Sequences[0];
var particleTime = particles[i].ConstantLifetime - particles[i].Lifetime;
var frame = particleTime * sequence.FramesPerSecond * animationRate;
var currentFrame = sequence.Frames[(int)Math.Floor(frame) % sequence.Frames.Length];
// Lerp frame coords and size
var subFrameTime = frame % 1.0f;
var offset = (currentFrame.StartMins * (1 - subFrameTime)) + (currentFrame.EndMins * subFrameTime);
var scale = ((currentFrame.StartMaxs - currentFrame.StartMins) * (1 - subFrameTime))
+ ((currentFrame.EndMaxs - currentFrame.EndMins) * subFrameTime);
GL.Uniform2(uvOffsetLocation, offset.X, offset.Y);
GL.Uniform2(uvScaleLocation, scale.X * finalTextureScaleU, scale.Y * finalTextureScaleV);
}
else
{
GL.Uniform2(uvOffsetLocation, 1f, 1f);
GL.Uniform2(uvScaleLocation, finalTextureScaleU, finalTextureScaleV);
}
// Color uniform
GL.Uniform3(colorLocation, particles[i].Color.X, particles[i].Color.Y, particles[i].Color.Z);
GL.Uniform1(alphaLocation, particles[i].Alpha * particles[i].AlphaAlternate);
GL.DrawArrays(PrimitiveType.TriangleStrip, 0, 4);
}
GL.BindVertexArray(0);
GL.UseProgram(0);
if (additive)
{
GL.BlendEquation(BlendEquationMode.FuncAdd);
}
GL.Disable(EnableCap.Blend);
}
