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webgl-planar-projection-with-projection-matrix.html
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<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>WebGL - Planar Projection with lines</title>
<link type="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<div class="description">
Planar Projection with lines
</div>
<canvas id="canvas"></canvas>
<div id="uiContainer">
<div id="ui">
</div>
</div>
</body>
<!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See https://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and https://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<script src="resources/webgl-lessons-ui.js"></script>
<script src="resources/webgl-utils.js"></script>
<script src="resources/m4.js"></script>
<script src="resources/primitives.js"></script>
<!-- vertex shader -->
<script id="vertex-shader-3d" type="x-shader/x-vertex">
attribute vec4 a_position;
attribute vec2 a_texcoord;
uniform mat4 u_projection;
uniform mat4 u_view;
uniform mat4 u_world;
uniform mat4 u_textureMatrix;
varying vec2 v_texcoord;
varying vec4 v_projectedTexcoord;
void main() {
// Multiply the position by the matrix.
vec4 worldPosition = u_world * a_position;
gl_Position = u_projection * u_view * worldPosition;
// Pass the texture coord to the fragment shader.
v_texcoord = a_texcoord;
v_projectedTexcoord = u_textureMatrix * worldPosition;
}
</script>
<!-- fragment shader -->
<script id="fragment-shader-3d" type="x-shader/x-fragment">
precision mediump float;
// Passed in from the vertex shader.
varying vec2 v_texcoord;
varying vec4 v_projectedTexcoord;
uniform vec4 u_colorMult;
uniform sampler2D u_texture;
uniform sampler2D u_projectedTexture;
void main() {
vec3 projectedTexcoord = v_projectedTexcoord.xyz / v_projectedTexcoord.w;
bool inRange =
projectedTexcoord.x >= 0.0 &&
projectedTexcoord.x <= 1.0 &&
projectedTexcoord.y >= 0.0 &&
projectedTexcoord.y <= 1.0;
vec4 projectedTexColor = texture2D(u_projectedTexture, projectedTexcoord.xy);
vec4 texColor = texture2D(u_texture, v_texcoord) * u_colorMult;
float projectedAmount = inRange ? 1.0 : 0.0;
gl_FragColor = mix(texColor, projectedTexColor, projectedAmount);
}
</script>
<!-- vertex shader -->
<script id="color-vertex-shader" type="x-shader/x-vertex">
attribute vec4 a_position;
uniform mat4 u_projection;
uniform mat4 u_view;
uniform mat4 u_world;
void main() {
// Multiply the position by the matrices.
gl_Position = u_projection * u_view * u_world * a_position;
}
</script>
<!-- fragment shader -->
<script id="color-fragment-shader" type="x-shader/x-fragment">
precision mediump float;
uniform vec4 u_color;
void main() {
gl_FragColor = u_color;
}
</script>
<script>
'use strict';
function main() {
// Get A WebGL context
/** @type {HTMLCanvasElement} */
const canvas = document.querySelector('#canvas');
const gl = canvas.getContext('webgl');
if (!gl) {
return;
}
// setup GLSL programs
const textureProgramInfo = webglUtils.createProgramInfo(gl, ['vertex-shader-3d', 'fragment-shader-3d']);
const colorProgramInfo = webglUtils.createProgramInfo(gl, ['color-vertex-shader', 'color-fragment-shader']);
const sphereBufferInfo = primitives.createSphereBufferInfo(
gl,
1, // radius
12, // subdivisions around
6, // subdivisions down
);
const planeBufferInfo = primitives.createPlaneBufferInfo(
gl,
20, // width
20, // height
1, // subdivisions across
1, // subdivisions down
);
const cubeLinesBufferInfo = webglUtils.createBufferInfoFromArrays(gl, {
position: [
-1, -1, -1,
1, -1, -1,
-1, 1, -1,
1, 1, -1,
-1, -1, 1,
1, -1, 1,
-1, 1, 1,
1, 1, 1,
],
indices: [
0, 1,
1, 3,
3, 2,
2, 0,
4, 5,
5, 7,
7, 6,
6, 4,
0, 4,
1, 5,
3, 7,
2, 6,
],
});
// make a 8x8 checkerboard texture
const checkerboardTexture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, checkerboardTexture);
gl.texImage2D(
gl.TEXTURE_2D,
0, // mip level
gl.LUMINANCE, // internal format
8, // width
8, // height
0, // border
gl.LUMINANCE, // format
gl.UNSIGNED_BYTE, // type
new Uint8Array([ // data
0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC,
0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF,
0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC,
0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF,
0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC,
0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF,
0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC,
0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF, 0xCC, 0xFF,
]));
gl.generateMipmap(gl.TEXTURE_2D);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
function loadImageTexture(url) {
// Create a texture.
const texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
// Fill the texture with a 1x1 blue pixel.
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, 1, 1, 0, gl.RGBA, gl.UNSIGNED_BYTE,
new Uint8Array([0, 0, 255, 255]));
// Asynchronously load an image
const image = new Image();
image.src = url;
image.addEventListener('load', function() {
// Now that the image has loaded make copy it to the texture.
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA,gl.UNSIGNED_BYTE, image);
// assumes this texture is a power of 2
gl.generateMipmap(gl.TEXTURE_2D);
render();
});
return texture;
}
const imageTexture = loadImageTexture('resources/f-texture.png'); /* webglfundamentals: url */
function degToRad(d) {
return d * Math.PI / 180;
}
const settings = {
cameraX: 2.75,
cameraY: 5,
posX: 2.5,
posY: 4.8,
posZ: 4.3,
targetX: 2.5,
targetY: 0,
targetZ: 3.5,
projWidth: 1,
projHeight: 1,
perspective: true,
fieldOfView: 45,
};
webglLessonsUI.setupUI(document.querySelector('#ui'), settings, [
{ type: 'slider', key: 'cameraX', min: -10, max: 10, change: render, precision: 2, step: 0.001, },
{ type: 'slider', key: 'cameraY', min: 1, max: 20, change: render, precision: 2, step: 0.001, },
{ type: 'slider', key: 'posX', min: -10, max: 10, change: render, precision: 2, step: 0.001, },
{ type: 'slider', key: 'posY', min: 1, max: 20, change: render, precision: 2, step: 0.001, },
{ type: 'slider', key: 'posZ', min: 1, max: 20, change: render, precision: 2, step: 0.001, },
{ type: 'slider', key: 'targetX', min: -10, max: 10, change: render, precision: 2, step: 0.001, },
{ type: 'slider', key: 'targetY', min: 0, max: 20, change: render, precision: 2, step: 0.001, },
{ type: 'slider', key: 'targetZ', min: -10, max: 20, change: render, precision: 2, step: 0.001, },
{ type: 'slider', key: 'projWidth', min: 0, max: 2, change: render, precision: 2, step: 0.001, },
{ type: 'slider', key: 'projHeight', min: 0, max: 2, change: render, precision: 2, step: 0.001, },
{ type: 'checkbox', key: 'perspective', change: render, },
{ type: 'slider', key: 'fieldOfView', min: 1, max: 179, change: render, },
]);
const fieldOfViewRadians = degToRad(60);
// Uniforms for each object.
const planeUniforms = {
u_colorMult: [0.5, 0.5, 1, 1], // lightblue
u_texture: checkerboardTexture,
u_world: m4.translation(0, 0, 0),
};
const sphereUniforms = {
u_colorMult: [1, 0.5, 0.5, 1], // pink
u_texture: checkerboardTexture,
u_world: m4.translation(2, 3, 4),
};
function drawScene(projectionMatrix, cameraMatrix) {
// Make a view matrix from the camera matrix.
const viewMatrix = m4.inverse(cameraMatrix);
const textureWorldMatrix = m4.lookAt(
[settings.posX, settings.posY, settings.posZ], // position
[settings.targetX, settings.targetY, settings.targetZ], // target
[0, 1, 0], // up
);
const textureProjectionMatrix = settings.perspective
? m4.perspective(
degToRad(settings.fieldOfView),
settings.projWidth / settings.projHeight,
0.1, // near
200) // far
: m4.orthographic(
-settings.projWidth / 2, // left
settings.projWidth / 2, // right
-settings.projHeight / 2, // bottom
settings.projHeight / 2, // top
0.1, // near
200); // far
let textureMatrix = m4.identity();
textureMatrix = m4.translate(textureMatrix, 0.5, 0.5, 0.5);
textureMatrix = m4.scale(textureMatrix, 0.5, 0.5, 0.5);
textureMatrix = m4.multiply(textureMatrix, textureProjectionMatrix);
// use the inverse of this world matrix to make
// a matrix that will transform other positions
// to be relative this world space.
textureMatrix = m4.multiply(
textureMatrix,
m4.inverse(textureWorldMatrix));
gl.useProgram(textureProgramInfo.program);
// set uniforms that are the same for both the sphere and plane
webglUtils.setUniforms(textureProgramInfo, {
u_view: viewMatrix,
u_projection: projectionMatrix,
u_textureMatrix: textureMatrix,
u_projectedTexture: imageTexture,
});
// ------ Draw the sphere --------
// Setup all the needed attributes.
webglUtils.setBuffersAndAttributes(gl, textureProgramInfo, sphereBufferInfo);
// Set the uniforms unique to the sphere
webglUtils.setUniforms(textureProgramInfo, sphereUniforms);
// calls gl.drawArrays or gl.drawElements
webglUtils.drawBufferInfo(gl, sphereBufferInfo);
// ------ Draw the plane --------
// Setup all the needed attributes.
webglUtils.setBuffersAndAttributes(gl, textureProgramInfo, planeBufferInfo);
// Set the uniforms we just computed
webglUtils.setUniforms(textureProgramInfo, planeUniforms);
// calls gl.drawArrays or gl.drawElements
webglUtils.drawBufferInfo(gl, planeBufferInfo);
// ------ Draw the cube ------
gl.useProgram(colorProgramInfo.program);
// Setup all the needed attributes.
webglUtils.setBuffersAndAttributes(gl, colorProgramInfo, cubeLinesBufferInfo);
// scale the cube in Z so it's really long
// to represent the texture is being projected to
// infinity
const mat = m4.multiply(
textureWorldMatrix, m4.inverse(textureProjectionMatrix));
// Set the uniforms we just computed
webglUtils.setUniforms(colorProgramInfo, {
u_color: [0, 0, 0, 1],
u_view: viewMatrix,
u_projection: projectionMatrix,
u_world: mat,
});
// calls gl.drawArrays or gl.drawElements
webglUtils.drawBufferInfo(gl, cubeLinesBufferInfo, gl.LINES);
}
// Draw the scene.
function render() {
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
gl.enable(gl.CULL_FACE);
gl.enable(gl.DEPTH_TEST);
// Clear the canvas AND the depth buffer.
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// Compute the projection matrix
const aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
const projectionMatrix =
m4.perspective(fieldOfViewRadians, aspect, 1, 2000);
// Compute the camera's matrix using look at.
const cameraPosition = [settings.cameraX, settings.cameraY, 7];
const target = [0, 0, 0];
const up = [0, 1, 0];
const cameraMatrix = m4.lookAt(cameraPosition, target, up);
drawScene(projectionMatrix, cameraMatrix);
}
render();
}
main();
</script>
</html>