introduce lineDrawer
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Magnus Ulimoen
parent
d1e89bf20e
commit
cd72ce3477
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@ -1,32 +1,9 @@
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function lineProgram(ctx) {
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const LINE_VERTEX_SHADER = String.raw`
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#version 100
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attribute mediump float aX;
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attribute mediump float aY;
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uniform vec4 uBbox;
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void main() {
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mediump float x = (aX - uBbox.x)*uBbox.y;
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mediump float y = (aY - uBbox.z)*uBbox.w;
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gl_Position = vec4(2.0*x - 1.0, 2.0*y - 1.0, 1.0, 1.0);
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}
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`;
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const LINE_FRAGMENT_SHADER = String.raw`
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#version 100
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void main() {
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gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);
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}
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`;
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function compile_and_link(ctx, vsource, fsource) {
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const program = ctx.createProgram();
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const vsShader = ctx.createShader(ctx.VERTEX_SHADER);
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ctx.shaderSource(vsShader, LINE_VERTEX_SHADER);
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ctx.shaderSource(vsShader, vsource);
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const fsShader = ctx.createShader(ctx.FRAGMENT_SHADER);
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ctx.shaderSource(fsShader, LINE_FRAGMENT_SHADER);
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ctx.shaderSource(fsShader, fsource);
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ctx.compileShader(vsShader);
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ctx.compileShader(fsShader);
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@ -45,10 +22,121 @@ function lineProgram(ctx) {
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ctx.deleteShader(vsShader);
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ctx.deleteShader(fsShader);
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const uBbox = ctx.getUniformLocation(program, "uBbox");
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return program;
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}
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return {program: program, uniforms: {"uBbox": uBbox}};
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};
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class LineDrawer {
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constructor(ctx) {
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function lineProgram(ctx) {
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const LINE_VERTEX_SHADER = String.raw`
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#version 100
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attribute mediump float aX;
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attribute mediump float aY;
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uniform vec4 uBbox;
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void main() {
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mediump float x = (aX - uBbox.x)*uBbox.y;
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mediump float y = (aY - uBbox.z)*uBbox.w;
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gl_Position = vec4(2.0*x - 1.0, 2.0*y - 1.0, 1.0, 1.0);
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}
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`;
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const LINE_FRAGMENT_SHADER = String.raw`
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#version 100
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void main() {
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gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);
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}
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`;
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const program = compile_and_link(ctx, LINE_VERTEX_SHADER, LINE_FRAGMENT_SHADER);
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const uBbox = ctx.getUniformLocation(program, "uBbox");
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return {inner: program, uniforms: {"uBbox": uBbox}};
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};
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this.program = lineProgram(ctx);
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this.ctx = ctx;
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}
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set_xy(width, height, xBuffer, yBuffer, bbox) {
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const ctx = this.ctx;
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ctx.useProgram(this.program.inner);
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{
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let loc = ctx.getAttribLocation(this.program.inner, "aX");
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ctx.bindBuffer(ctx.ARRAY_BUFFER, xBuffer);
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ctx.vertexAttribPointer(loc, 1, ctx.FLOAT, false, 0, 0);
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ctx.enableVertexAttribArray(loc);
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loc = ctx.getAttribLocation(this.program.inner, "aY");
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ctx.bindBuffer(ctx.ARRAY_BUFFER, yBuffer);
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ctx.vertexAttribPointer(loc, 1, ctx.FLOAT, false, 0, 0);
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ctx.enableVertexAttribArray(loc);
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}
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const lineIdxBuffer = new Uint16Array(2*width*height - 1);
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{
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let n = 0;
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for (let j = 0; j < height; j++) {
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for (let i = 0; i < width; i++) {
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if (j % 2 == 0) {
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lineIdxBuffer[n] = width*j + i;
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} else {
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lineIdxBuffer[n] = width*(j + 1) - i - 1;
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}
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n += 1;
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}
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}
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let m = lineIdxBuffer[n-1];
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let updown = "down";
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let lr;
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if (height % 2 === 0) {
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lr = "left";
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} else {
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lr = "right";
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}
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for (let i = 0; i < width; i++) {
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for (let j = 0; j < height-1; j++) {
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if (updown === "up") {
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m += width;
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} else {
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m -= width;
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}
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lineIdxBuffer[n] = m;
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n += 1;
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}
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if (n === 2*width*height - 1) {
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continue;
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}
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if (lr === "left") {
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m += 1;
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} else {
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m -= 1;
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}
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lineIdxBuffer[n] = m;
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n += 1;
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if (updown === "down") {
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updown = "up";
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} else {
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updown = "down";
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}
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}
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}
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this.indexBuffer = ctx.createBuffer();
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ctx.bindBuffer(ctx.ELEMENT_ARRAY_BUFFER, this.indexBuffer);
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ctx.bufferData(ctx.ELEMENT_ARRAY_BUFFER, lineIdxBuffer, ctx.STATIC_DRAW);
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ctx.uniform4f(this.program.uniforms.uBbox, bbox[0], 1.0/(bbox[1] - bbox[0]), bbox[2], 1.0/(bbox[3] - bbox[2]));
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this.width = width;
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this.height = height;
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}
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draw() {
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const ctx = this.ctx;
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ctx.useProgram(this.program.inner);
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ctx.bindBuffer(ctx.ELEMENT_ARRAY_BUFFER, this.indexBuffer);
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ctx.drawElements(ctx.LINE_STRIP, 2*this.width*this.height - 1, ctx.UNSIGNED_SHORT, 0);
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}
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}
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(async function run() {
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const canvas = document.getElementById("glCanvas");
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@ -88,91 +176,24 @@ function lineProgram(ctx) {
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gl.enable(gl.DEPTH_TEST);
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gl.depthFunc(gl.LEQUAL);
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gl.disable(gl.CULL_FACE);
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const lineProg = lineProgram(gl);
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gl.useProgram(lineProg.program);
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// Transfer x, y to cpu, prepare fBuffer
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const xBuffer = gl.createBuffer();
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const yBuffer = gl.createBuffer();
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{
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let loc = gl.getAttribLocation(lineProg.program, "aX");
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gl.bindBuffer(gl.ARRAY_BUFFER, xBuffer);
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gl.vertexAttribPointer(loc, 1, gl.FLOAT, false, 0, 0);
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gl.enableVertexAttribArray(loc);
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gl.bufferData(gl.ARRAY_BUFFER, x, gl.STATIC_DRAW);
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loc = gl.getAttribLocation(lineProg.program, "aY");
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gl.bindBuffer(gl.ARRAY_BUFFER, yBuffer);
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gl.vertexAttribPointer(loc, 1, gl.FLOAT, false, 0, 0);
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gl.enableVertexAttribArray(loc);
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gl.bufferData(gl.ARRAY_BUFFER, y, gl.STATIC_DRAW);
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}
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// Create triangles covering the domain
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const lineIdxBuffer = new Uint16Array(2*width*height - 1);
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{
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let n = 0;
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for (let j = 0; j < height; j++) {
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for (let i = 0; i < width; i++) {
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if (j % 2 == 0) {
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lineIdxBuffer[n] = width*j + i;
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} else {
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lineIdxBuffer[n] = width*(j + 1) - i - 1;
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}
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n += 1;
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}
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}
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let m = lineIdxBuffer[n-1];
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let updown = "down";
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let lr;
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if (height % 2 === 0) {
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lr = "left";
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} else {
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lr = "right";
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}
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for (let i = 0; i < width; i++) {
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for (let j = 0; j < height-1; j++) {
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if (updown === "up") {
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m += width;
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} else {
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m -= width;
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}
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lineIdxBuffer[n] = m;
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n += 1;
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}
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if (n === 2*width*height - 1) {
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continue;
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}
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if (lr === "left") {
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m += 1;
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} else {
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m -= 1;
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}
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lineIdxBuffer[n] = m;
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n += 1;
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if (updown === "down") {
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updown = "up";
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} else {
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updown = "down";
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}
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}
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}
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const indexBuffer = gl.createBuffer();
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gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
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gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, lineIdxBuffer, gl.STATIC_DRAW);
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gl.lineWidth(1.0);
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gl.uniform4f(lineProg.uniforms.uBbox, bbox[0], 1.0/(bbox[1] - bbox[0]), bbox[2], 1.0/(bbox[3] - bbox[2]));
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const xBuffer = gl.createBuffer();
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const yBuffer = gl.createBuffer();
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gl.bindBuffer(gl.ARRAY_BUFFER, xBuffer);
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gl.bufferData(gl.ARRAY_BUFFER, x, gl.STATIC_DRAW);
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gl.bindBuffer(gl.ARRAY_BUFFER, yBuffer);
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gl.bufferData(gl.ARRAY_BUFFER, y, gl.STATIC_DRAW);
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const lineDrawer = new LineDrawer(gl);
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lineDrawer.set_xy(width, height, xBuffer, yBuffer, bbox);
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function drawMe() {
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gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
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gl.drawElements(gl.LINE_STRIP, 2*width*height - 1, gl.UNSIGNED_SHORT, 0);
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lineDrawer.draw();
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window.requestAnimationFrame(drawMe);
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}
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