func New() (s *Space, err error) {
s = new(Space)
s.accelProgram, err = loadShader()
if err != nil {
return nil, err
}
gl.GenVertexArrays(1, &s.vao)
gl.GenBuffers(1, &s.vbo)
gl.UseProgram(s.accelProgram)
gl.BindVertexArray(s.vao)
gl.BindBufferBase(gl.SHADER_STORAGE_BUFFER, 0, s.vbo)
return s, nil
}
func (s *Space) Step(dt float64) {
var prevProgram int32
gl.GetIntegerv(gl.CURRENT_PROGRAM, &prevProgram)
gl.UseProgram(s.accelProgram)
gl.BindVertexArray(s.vao)
gl.BindBufferBase(gl.SHADER_STORAGE_BUFFER, 0, s.vbo)
gl.BufferData(
gl.SHADER_STORAGE_BUFFER,
len(s.Particles)*int(unsafe.Sizeof(gpuParticle{})),
nil,
gl.DYNAMIC_COPY)
{ // send
mappedParticles, err := sliceMapParticlesBuffer(gl.WRITE_ONLY, len(s.Particles))
if err != nil {
panic(err)
}
for i, p := range s.Particles {
mappedParticles[i] = gpuParticle{
position: [2]float32{float32(p.Position.X), float32(p.Position.Y)},
mass: float32(p.Mass),
}
}
gl.UnmapBuffer(gl.SHADER_STORAGE_BUFFER)
}
gl.DispatchCompute(uint32(len(s.Particles))/WORK_GROUP_LOCAL_SIZE, 1, 1)
gl.MemoryBarrier(gl.SHADER_STORAGE_BARRIER_BIT)
{ // receive
mappedParticles, err := sliceMapParticlesBuffer(gl.READ_ONLY, len(s.Particles))
if err != nil {
panic(err)
}
for i, q := range mappedParticles {
p := &s.Particles[i]
p.Position = p.Position.Add(p.Velocity.Mul(dt)).Add(
p.Acceleration.Mul(dt * dt).Mul(0.5))
oldAcceleration := p.Acceleration
p.Acceleration = vect.V{
float64(q.acceleration[0]), float64(q.acceleration[1]),
}
p.Velocity = p.Velocity.Add(
p.Acceleration.Add(oldAcceleration).Mul(0.5).Mul(dt))
}
gl.UnmapBuffer(gl.SHADER_STORAGE_BUFFER)
}
gl.UseProgram(uint32(prevProgram))
}