zworld/engine/render/pass/effect/particle_pass.go

package effect

// import (
// 	"github.com/go-gl/gl/v4.1-core/gl"
// 	"github.com/johanhenriksson/goworld/assets"
// 	"github.com/johanhenriksson/goworld/core/object"
// 	"github.com/johanhenriksson/goworld/core/transform"
// 	"github.com/johanhenriksson/goworld/math/random"
// 	"github.com/johanhenriksson/goworld/math/vec3"
// 	"github.com/johanhenriksson/goworld/render"
// 	"github.com/johanhenriksson/goworld/render/material"
// 	"github.com/johanhenriksson/goworld/render/vertex"
// )

// type ParticleDrawable interface {
// 	DrawParticles(render.Args)
// }

// // ParticlePass represents the particle system draw pass
// type ParticlePass struct {
// }

// // NewParticlePass creates a new particle system draw pass
// func NewParticlePass() *ParticlePass {
// 	return &ParticlePass{}
// }

// // Resize is called on window resize. Should update any window size-dependent buffers
// func (p *ParticlePass) Resize(width, height int) {}

// // DrawPass executes the particle pass
// func (p *ParticlePass) Draw(args render.Args, scene object.T) {

// }

// // Particle holds data about a single particle
// type Particle struct {
// 	Position vec3.T
// 	Velocity vec3.T
// 	Duration float32
// }

// // ParticleSystem holds the properties of a particle system effect
// type ParticleSystem struct {
// 	transform.T

// 	Particles []Particle
// 	Count     int
// 	Chance    float32
// 	MinVel    vec3.T
// 	MaxVel    vec3.T
// 	MinDur    float32
// 	MaxDur    float32

// 	positions vec3.Array
// 	mat       material.T
// 	vao       vertex.Array
// }

// // Update the particle system
// func (ps *ParticleSystem) Update(dt float32) {
// 	if len(ps.Particles) < ps.Count && random.Chance(ps.Chance) {
// 		// add particle

// 		p := Particle{
// 			Position: vec3.Zero,
// 			Velocity: vec3.Random(ps.MinVel, ps.MaxVel),
// 			Duration: random.Range(ps.MinDur, ps.MaxDur),
// 		}
// 		ps.Particles = append(ps.Particles, p)
// 	}

// 	for i := 0; i < len(ps.Particles); i++ {
// 		if ps.Particles[i].Duration < 0 {
// 			// dead
// 			ps.remove(i)
// 			i--
// 		}
// 	}

// 	for i, p := range ps.Particles {
// 		ps.Particles[i].Duration -= dt
// 		ps.Particles[i].Position = p.Position.Add(p.Velocity.Scaled(dt))
// 		ps.positions[i] = p.Position
// 	}

// 	ps.vao.Buffer("geometry", ps.positions[:len(ps.Particles)])
// }

// func (ps *ParticleSystem) remove(i int) {
// 	ps.Particles[len(ps.Particles)-1], ps.Particles[i] = ps.Particles[i], ps.Particles[len(ps.Particles)-1]
// 	ps.Particles = ps.Particles[:len(ps.Particles)-1]
// }

// // Draw the particle system
// func (ps *ParticleSystem) Draw(args render.Args) {
// 	args = args.Apply(ps.World())

// 	render.Blend(true)
// 	render.BlendFunc(gl.ONE, gl.ONE)
// 	render.DepthOutput(false)

// 	ps.mat.Use()
// 	ps.mat.Vec3("eye", args.Position)
// 	ps.mat.Mat4("model", args.Transform)
// 	ps.mat.Mat4("vp", args.VP)
// 	ps.vao.Draw()

// 	render.DepthOutput(true)
// }

// // NewParticleSystem creates a new particle system
// func NewParticleSystem(position vec3.T) *ParticleSystem {
// 	count := 8
// 	mat := assets.GetMaterial("billboard")
// 	ps := &ParticleSystem{
// 		T: transform.New(position, vec3.Zero, vec3.One),

// 		Count:  count,
// 		Chance: 0.08,
// 		MinVel: vec3.New(-0.05, 0.4, -0.05),
// 		MaxVel: vec3.New(0.05, 0.6, 0.05),
// 		MinDur: 2,
// 		MaxDur: 3,

// 		mat:       mat,
// 		positions: make(vec3.Array, count),
// 	}

// 	//mat.SetupVertexPointers()

// 	return ps
// }