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133 lines
3.5 KiB
133 lines
3.5 KiB
import { ENTITIES, RAD } from './enums';
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import Random from './random';
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const Arc = {
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create: function(bounds, grid) {
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let arc = {
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centerX: Random.num(0, bounds.width),
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centerY: Random.num(0, bounds.height),
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clockwise: Random.bool(),
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endX: 0,
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endY: 0,
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length: Random.num(RAD.t90, RAD.t360),
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radius: Random.num(100, 200),
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theta: Random.num(RAD.t90, RAD.t360)
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};
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arc.cosTheta = Math.cos(arc.theta);
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arc.sinTheta = Math.sin(arc.theta);
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arc.endX = arc.centerX + arc.radius * arc.cosTheta;
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arc.endY = arc.centerY - arc.radius * arc.sinTheta;
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arc = Arc.overflow(arc, bounds);
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// If starting in a hazard, recurse.
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if (grid.getPoint({ x: arc.endX, y: arc.endY, type: ENTITIES.HAZARD })) {
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arc = Arc.create(bounds, grid);
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}
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return arc;
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},
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step: function(arc, bounds, speed) {
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// Ensure constant velocity and theta between 0 and 2π.
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const delta = speed / arc.radius;
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arc.length -= delta;
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arc.theta += (arc.clockwise ? -delta : +delta);
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arc.theta = (arc.theta > 0 ? arc.theta % RAD.t360 : RAD.t360 + arc.theta);
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arc.cosTheta = Math.cos(arc.theta);
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arc.sinTheta = Math.sin(arc.theta);
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arc.endX = arc.centerX + arc.radius * arc.cosTheta;
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arc.endY = arc.centerY - arc.radius * arc.sinTheta;
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// Overflow.
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arc = Arc.overflow(arc, bounds);
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return arc;
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},
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randomize: function(arc) {
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arc.length = Random.num(RAD.t90, RAD.t360);
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arc = Arc.changeRadius(arc, Random.num(100, 200));
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if (Random.bool(0.8)) {
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arc = Arc.reverse(arc);
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}
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return arc;
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},
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overflow: function(arc, bounds) {
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if (arc.endX < 0) {
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arc.endX += bounds.width;
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arc.centerX += bounds.width
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} else if (arc.endX > bounds.width) {
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arc.endX -= bounds.width;
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arc.centerX -= bounds.width
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}
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if (arc.endY < 0) {
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arc.endY += bounds.height;
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arc.centerY += bounds.height
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} else if (arc.endY > bounds.height) {
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arc.endY -= bounds.height;
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arc.centerY -= bounds.height
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}
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return arc;
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},
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changeRadius: function(arc, newRadius) {
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const r0 = arc.radius;
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const r1 = newRadius;
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// Moves arc center to new radius while keeping theta constant.
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arc.centerX -= (r1 - r0) * arc.cosTheta;
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arc.centerY += (r1 - r0) * arc.sinTheta;
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arc.radius = r1;
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return arc;
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},
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reverse: function(arc) {
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arc.clockwise = !arc.clockwise;
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arc.theta = (arc.theta + RAD.t180) % RAD.t360;
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arc.cosTheta = Math.cos(arc.theta);
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arc.sinTheta = Math.sin(arc.theta);
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arc.centerX -= (2 * arc.radius) * arc.cosTheta;
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arc.centerY += (2 * arc.radius) * arc.sinTheta;
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return arc;
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},
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follow: function(arc, arcToFollow) {
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if (arc.clockwise !== arcToFollow.clockwise) {
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arc = Arc.reverse(arc);
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}
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if (Math.abs(arc.theta - arcToFollow.theta) > 0.2) {
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arc = Arc.changeRadius(arc, 50);
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} else {
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arc = Arc.changeRadius(arc, arcToFollow.radius);
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}
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return arc;
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},
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evade: function(arc) {
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arc = Arc.changeRadius(arc, 20);
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arc.length = 1;
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return arc;
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}
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}
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export default Arc;
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