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add constraints on pan and zoom-over point (#904)

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This commit is contained in:
Bruce Martin
2019-08-28 17:56:46 -07:00
committed by GitHub
parent 78a43402cb
commit c35f94fe6d
1 changed files with 36 additions and 11 deletions
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47
client/src/util/camera.js
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@@ -1,13 +1,20 @@
import { vec2, mat3 } from "gl-matrix";
const EPSILON = 0.000001;
const scaleSpeed = 0.5;
const scaleMax = 3.0;
const scaleMin = 0.5;
const panBound = 0.8;
// private
const scratch0 = new Float32Array(16);
const scratch1 = new Float32Array(16);
function clamp(val, rng) {
return Math.max(Math.min(val, rng[1]), rng[0]);
}
class Camera {
constructor(canvas) {
this.prevEvent = {
@@ -33,24 +40,42 @@ class Camera {
}
pan(dx, dy) {
mat3.translate(this.viewMatrix, this.viewMatrix, [dx, dy]);
mat3.invert(this.viewMatrixInv, this.viewMatrix);
const m = this.viewMatrix;
const dyRange = [
-panBound - (m[7] + 1) / m[4],
panBound - (m[7] - 1) / m[4]
];
const dxRange = [
-panBound - (m[6] + 1) / m[0],
panBound - (m[6] - 1) / m[0]
];
const dxClamped = clamp(dx, dxRange);
const dyClamped = clamp(dy, dyRange);
if (Math.abs(dxClamped) <= EPSILON && Math.abs(dyClamped) <= EPSILON)
return;
mat3.translate(m, m, [dxClamped, dyClamped]);
mat3.invert(this.viewMatrixInv, m);
}
zoomAt(d, x = 0, y = 0) {
/*
Set camera zoom at [x,y]
Camera zoom at [x,y]
*/
const dClamped =
Math.max(Math.min(d * this.viewMatrix[0], scaleMax), scaleMin) /
this.viewMatrix[0];
if (dClamped === 1) return;
const m = this.viewMatrix;
const bounds = [-panBound, panBound];
x = clamp(x, bounds);
y = clamp(y, bounds);
mat3.translate(this.viewMatrix, this.viewMatrix, [x, y]);
mat3.scale(this.viewMatrix, this.viewMatrix, [dClamped, dClamped]);
mat3.translate(this.viewMatrix, this.viewMatrix, [-x, -y]);
const dClamped = clamp(d * m[0], [scaleMin, scaleMax]) / m[0];
if (Math.abs(1 - dClamped) <= EPSILON) return; // noop request
mat3.invert(this.viewMatrixInv, this.viewMatrix);
mat3.translate(m, m, [x, y]);
mat3.scale(m, m, [dClamped, dClamped]);
mat3.translate(m, m, [-x, -y]);
mat3.invert(this.viewMatrixInv, m);
}
/*