ludus/pkg/p5.js
2025-07-08 16:38:47 -04:00

94 lines
3.1 KiB
JavaScript

import {eq_vect, eq_color, resolve_color, get_turtle_color, set_turtle_color, turtle_radius, turtle_angle, turn_to_rad, turtle_init, command_to_state, background_color, rotate, last} from "./turtle_geometry.js"
function states_to_call (prev, curr) {
const calls = []
// whose state should we use?
// pen states will only differ on more than one property
// if we use `loadstate`
// my sense is `prev`, but that may change
if (prev.pendown && !eq_vect(prev.position, curr.position)) {
calls.push(["line", prev.position[0], prev.position[1], curr.position[0], curr.position[1]])
}
if (!eq_color(curr.pencolor, prev.pencolor)) {
calls.push(["stroke", ...resolve_color(curr.pencolor)])
}
if (curr.penwidth !== prev.penwidth) {
calls.push(["strokeWeight", curr.penwidth])
}
return calls
}
function p5_call_root () {
return [
["background", ...resolve_color(background_color)],
["push"],
["rotate", Math.PI],
["scale", -1, 1],
["stroke", ...resolve_color(turtle_init.pencolor)],
]
}
function p5_render_turtle (state, calls) {
if (!state.visible) return
calls.push(["push"])
const [r, g, b, a] = get_turtle_color()
calls.push(["fill", r, g, b, a])
const {heading, pencolor, position: [x, y], pendown, penwidth} = state
const origin = [0, turtle_radius]
const [x1, y1] = origin
const [x2, y2] = rotate(origin, turtle_angle)
const [x3, y3] = rotate(origin, -turtle_angle)
calls.push(["translate", x, y])
// need negative turtle rotation with the other p5 translations
calls.push(["rotate", -turn_to_rad(heading)])
calls.push(["noStroke"])
calls.push(["beginShape"])
calls.push(["vertex", x1, y1])
calls.push(["vertex", x2, y2])
calls.push(["vertex", x3, y3])
calls.push(["endShape"])
calls.push(["strokeWeight", penwidth])
calls.push(["stroke", ...resolve_color(pencolor)])
if (pendown) calls.push(["line", 0, 0, x1, y1])
calls.push(["pop"])
return calls
}
export function p5 (commands) {
const all_states = {}
for (const command of commands) {
const [turtle_id, _, this_command] = command
let stack = all_states[turtle_id]
if (!stack) {
const new_stack = [turtle_init]
all_states[turtle_id] = new_stack
stack = new_stack
}
let prev_state = last(all_states[turtle_id])
const new_state = command_to_state(prev_state, this_command)
all_states[turtle_id].push(new_state)
}
console.log(all_states)
const [r, g, b, _] = resolve_color(background_color)
if ((r + g + b)/3 > 128) set_turtle_color([0, 0, 0, 150])
const p5_calls = [...p5_call_root()]
for (const states of Object.values(all_states)) {
p5_calls.push(["strokeWeight", 1])
p5_calls.push(["stroke", 255])
for (let i = 1; i < states.length; ++i) {
const prev = states[i - 1]
const curr = states[i]
const calls = states_to_call(prev, curr)
for (const call of calls) {
p5_calls.push(call)
}
}
p5_calls[0] = ["background", ...resolve_color(background_color)]
p5_render_turtle(states[states.length - 1], p5_calls)
}
p5_calls.push(["pop"])
return p5_calls
}