141 lines
3.6 KiB
Plaintext
141 lines
3.6 KiB
Plaintext
// particles2d.cm - Particle system factory
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//
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// Creates particle data objects that register with film2d
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// Also provides emitter update logic
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var film2d = use('film2d')
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var random = use('random').random
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var particles2d_proto = {
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type: 'particles',
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destroy: function() {
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film2d.unregister(this._id)
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}
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}
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// Emitter management
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var emitters = {
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// Spawn a particle for an emitter
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spawn: function(emitter) {
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emitter.particles.push({
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pos: {
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x: emitter.pos.x + (random() - 0.5) * emitter.spawn_area.width,
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y: emitter.pos.y + (random() - 0.5) * emitter.spawn_area.height
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},
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velocity: {
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x: emitter.velocity.x + (random() - 0.5) * emitter.velocity_var.x,
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y: emitter.velocity.y + (random() - 0.5) * emitter.velocity_var.y
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},
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life: emitter.life,
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time: 0,
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max_scale: emitter.scale + (random() - 0.5) * emitter.scale_var,
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scale: 0,
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color: {
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r: emitter.color.r,
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g: emitter.color.g + (random() - 0.5) * 0.3,
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b: emitter.color.b,
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a: 1
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}
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})
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},
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// Update an emitter and its particles
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update: function(emitter, dt) {
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// Spawn new particles
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if (emitter.rate > 0) {
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emitter.spawn_timer = (emitter.spawn_timer || 0) + dt
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var pp = 1 / emitter.rate
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while (emitter.spawn_timer > pp) {
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emitter.spawn_timer -= pp
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emitters.spawn(emitter)
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}
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}
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// Update existing particles
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for (var i = length(emitter.particles) - 1; i >= 0; i--) {
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var p = emitter.particles[i]
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p.time += dt
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p.pos.x += p.velocity.x * dt
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p.pos.y += p.velocity.y * dt
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// Scale animation
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var grow_for = emitter.grow_for || 0.3
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var shrink_for = emitter.shrink_for || 0.5
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if (p.time < grow_for) {
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p.scale = lerp(0, p.max_scale, p.time / grow_for)
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} else if (p.time > p.life - shrink_for) {
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p.scale = lerp(0, p.max_scale, (p.life - p.time) / shrink_for)
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} else {
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p.scale = p.max_scale
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}
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// Alpha fade
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var alpha = 1
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if (p.time > p.life * 0.7) {
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alpha = 1 - (p.time - p.life * 0.7) / (p.life * 0.3)
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}
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p.color.a = alpha
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// Remove dead particles
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if (p.time >= p.life) {
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emitter.particles.splice(i, 1)
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}
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}
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// Sync to film2d if handle provided
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if (emitter.handle) {
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emitter.handle.particles = emitter.particles
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}
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},
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// Create an emitter config
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create: function(config) {
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return {
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pos: config.pos || {x: 0, y: 0},
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spawn_area: config.spawn_area || {width: 10, height: 10},
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velocity: config.velocity || {x: 0, y: 100},
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velocity_var: config.velocity_var || {x: 20, y: 20},
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life: config.life || 2,
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rate: config.rate || 10,
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scale: config.scale || 1,
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scale_var: config.scale_var || 0.3,
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grow_for: config.grow_for || 0.3,
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shrink_for: config.shrink_for || 0.5,
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color: config.color || {r: 1, g: 1, b: 1, a: 1},
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spawn_timer: 0,
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particles: [],
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handle: config.handle || null
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}
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}
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}
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function lerp(a, b, t) { return a + (b - a) * t }
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// Factory function - auto-registers with film2d
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var factory = function(props) {
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var defaults = {
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type: 'particles',
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pos: {x: 0, y: 0},
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image: null,
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width: 16,
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height: 16,
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plane: 'default',
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layer: 0,
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groups: [],
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particles: [],
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opacity: 1,
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tint: {r: 1, g: 1, b: 1, a: 1}
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}
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var data = object(defaults, props)
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var newparticles = meme(particles2d_proto, data)
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film2d.register(newparticles)
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return newparticles
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}
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// Attach emitter helpers to factory
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factory.emitters = emitters
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return factory |