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))
}
func (s *MainState) Render() error {
gl.UseProgram(s.program)
gl.UniformMatrix4fv(s.projectionUniform, 1, false, &s.projection[0])
/*
gl.BindVertexArray(s.vao)
gl.BindBuffer(gl.ARRAY_BUFFER, s.vbo)
*/
gl.BufferData(
gl.ARRAY_BUFFER,
int(PARTICLE_COUNT_DEFAULT*unsafe.Sizeof([2]float32{})),
nil,
gl.STREAM_DRAW)
data, err := sliceMap2Float32Buffer(gl.WRITE_ONLY, PARTICLE_COUNT_DEFAULT)
if err != nil {
return err
}
for i := range data {
p := &s.space.Particles[i]
if p == nil {
return fmt.Errorf("no particle of id %d", i)
}
data[i][0] = float32(p.Position.X)
data[i][1] = float32(p.Position.Y)
}
gl.UnmapBuffer(gl.ARRAY_BUFFER)
data = nil
positionAttrib := uint32(gl.GetAttribLocation(s.program, gl.Str("position\x00")))
gl.EnableVertexAttribArray(positionAttrib)
gl.VertexAttribPointer(positionAttrib, 2, gl.FLOAT, false, 0, gl.PtrOffset(0))
gl.ClearColor(0, 0, 0, 1)
gl.Clear(gl.COLOR_BUFFER_BIT)
gl.DrawArrays(gl.POINTS, 0, PARTICLE_COUNT_DEFAULT)
return nil
}
func (s *MainState) Render() error {
program := s.program
gl.UseProgram(program)
projectionUniform := gl.GetUniformLocation(program, gl.Str("projection\x00"))
gl.UniformMatrix4fv(projectionUniform, 1, false, &projection[0])
gl.Flush()
buffer := s.vertexBuffer
gl.BindBuffer(gl.ARRAY_BUFFER, buffer)
gl.BufferData(
gl.ARRAY_BUFFER,
int(PARTICLE_COUNT_DEFAULT*unsafe.Sizeof([2]float32{})),
nil,
gl.STREAM_DRAW)
dataPointer := gl.MapBuffer(gl.ARRAY_BUFFER, gl.WRITE_ONLY)
if dataPointer == nil {
return fmt.Errorf("buffer data pointer is nil")
}
data := (*[PARTICLE_COUNT_DEFAULT][2]float32)(dataPointer)
gl.ClearColor(0, 0, 0, 1)
gl.Clear(gl.COLOR_BUFFER_BIT)
for i := range data {
p := s.space.Particle(i)
if p == nil {
return fmt.Errorf("no particle of id %d", i)
}
data[i][0] = float32(p.Position.X)
data[i][1] = float32(p.Position.Y)
}
gl.UnmapBuffer(gl.ARRAY_BUFFER)
gl.DrawArrays(gl.POINTS, 0, PARTICLE_COUNT_DEFAULT)
return nil
}