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webgl-ramp-texture.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 - Ramp Texture</title>
<link type="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<div class="description">
Drag slider to rotate
</div>
<canvas id="canvas"></canvas>
<div id="uiContainer">
<div id="ui">
<div id="fRotation"></div>
</div>
</div>
</body>
<!-- vertex shader -->
<script id="vertex-shader-3d" type="x-shader/x-vertex">
attribute vec4 a_position;
attribute vec3 a_normal;
uniform mat4 u_worldViewProjection;
uniform mat4 u_worldInverseTranspose;
varying vec3 v_normal;
void main() {
// Multiply the position by the matrix.
gl_Position = u_worldViewProjection * a_position;
// orient the normals and pass to the fragment shader
v_normal = mat3(u_worldInverseTranspose) * a_normal;
}
</script>
<!-- fragment shader -->
<script id="fragment-shader-3d" type="x-shader/x-fragment">
precision mediump float;
// Passed in from the vertex shader.
varying vec3 v_normal;
uniform vec3 u_reverseLightDirection;
uniform vec4 u_color;
uniform sampler2D u_ramp;
void main() {
// because v_normal is a varying it's interpolated
// so it will not be a unit vector. Normalizing it
// will make it a unit vector again
vec3 normal = normalize(v_normal);
float cosAngle = dot(normal, u_reverseLightDirection);
// convert from -1 <-> 1 to 0 <-> 1
float u = cosAngle * 0.5 + 0.5;
// make a texture coordinate
vec2 uv = vec2(u, 0.5);
// lookup a value from a 1d texture
vec4 rampColor = texture2D(u_ramp, uv);
gl_FragColor = u_color;
gl_FragColor *= rampColor;
}
</script>
<!--
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-utils.js"></script>
<script src="resources/webgl-lessons-ui.js"></script>
<script src="resources/m4.js"></script>
<script src="resources/headdata.js"></script>
<script>
"use strict";
function main() {
// Get A WebGL context
/** @type {HTMLCanvasElement} */
var canvas = document.querySelector("#canvas");
var gl = canvas.getContext("webgl");
if (!gl) {
return;
}
// setup GLSL program
var program = webglUtils.createProgramFromScripts(gl, ["vertex-shader-3d", "fragment-shader-3d"]);
// look up where the vertex data needs to go.
var positionLocation = gl.getAttribLocation(program, "a_position");
var normalLocation = gl.getAttribLocation(program, "a_normal");
// lookup uniforms
var worldViewProjectionLocation = gl.getUniformLocation(program, "u_worldViewProjection");
var worldInverseTransposeLocation = gl.getUniformLocation(program, "u_worldInverseTranspose");
var colorLocation = gl.getUniformLocation(program, "u_color");
var rampLocation = gl.getUniformLocation(program, "u_ramp");
var reverseLightDirectionLocation =
gl.getUniformLocation(program, "u_reverseLightDirection");
// Create a buffer to put positions in
var positionBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Put geometry data into buffer
var numElements = setGeometry(gl);
// Create a buffer to put normals in
var normalBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = normalBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, normalBuffer);
// Put normals data into buffer
setNormals(gl);
var tex = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, tex);
gl.texImage2D(
gl.TEXTURE_2D, // target
0, // mip level
gl.LUMINANCE, // internal format
2, // width
1, // height
0, // border
gl.LUMINANCE, // format
gl.UNSIGNED_BYTE, // type
new Uint8Array([90, 255]));
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
function radToDeg(r) {
return r * 180 / Math.PI;
}
function degToRad(d) {
return d * Math.PI / 180;
}
var fieldOfViewRadians = degToRad(60);
var fRotationRadians = 0;
drawScene();
// Setup a ui.
webglLessonsUI.setupSlider("#fRotation", {value: radToDeg(fRotationRadians), slide: updateRotation, min: -360, max: 360});
function updateRotation(event, ui) {
fRotationRadians = degToRad(ui.value);
drawScene();
}
// Draw the scene.
function drawScene() {
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
// Clear the canvas AND the depth buffer.
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// Turn on culling. By default backfacing triangles
// will be culled.
gl.enable(gl.CULL_FACE);
// Enable the depth buffer
gl.enable(gl.DEPTH_TEST);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// Turn on the position attribute
gl.enableVertexAttribArray(positionLocation);
// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Tell the position attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 3; // 3 components per iteration
var type = gl.FLOAT; // the data is 32bit floats
var normalize = false; // don't normalize the data
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
positionLocation, size, type, normalize, stride, offset);
// Turn on the normal attribute
gl.enableVertexAttribArray(normalLocation);
// Bind the normal buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, normalBuffer);
// Tell the attribute how to get data out of normalBuffer (ARRAY_BUFFER)
var size = 3; // 3 components per iteration
var type = gl.FLOAT; // the data is 32bit floating point values
var normalize = false; // normalize the data (convert from 0-255 to 0-1)
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
normalLocation, size, type, normalize, stride, offset);
// Compute the projection matrix
var aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
var zNear = 1;
var zFar = 50;
var projectionMatrix = m4.perspective(fieldOfViewRadians, aspect, zNear, zFar);
// Compute the camera's matrix
var camera = [0, 0, 20];
var target = [0, 0, 0];
var up = [0, 1, 0];
var cameraMatrix = m4.lookAt(camera, target, up);
// Make a view matrix from the camera matrix.
var viewMatrix = m4.inverse(cameraMatrix);
// Compute a view projection matrix
var viewProjectionMatrix = m4.multiply(projectionMatrix, viewMatrix);
// Draw a F at the origin
var worldMatrix = m4.yRotation(fRotationRadians);
// Multiply the matrices.
var worldViewProjectionMatrix = m4.multiply(viewProjectionMatrix, worldMatrix);
var worldInverseMatrix = m4.inverse(worldMatrix);
var worldInverseTransposeMatrix = m4.transpose(worldInverseMatrix);
// Set the matrices
gl.uniformMatrix4fv(worldViewProjectionLocation, false, worldViewProjectionMatrix);
gl.uniformMatrix4fv(worldInverseTransposeLocation, false, worldInverseTransposeMatrix);
// Set the color to use
gl.uniform4fv(colorLocation, [0.2, 1, 0.2, 1]); // green
// set the light direction.
gl.uniform3fv(reverseLightDirectionLocation, m4.normalize([-1.75, 0.7, 1]));
// bind the texture to active texture unit 0
gl.activeTexture(gl.TEXTURE0 + 0);
gl.bindTexture(gl.TEXTURE_2D, tex);
// tell the shader that u_ramp should use the texture on texture unit 0
gl.uniform1i(rampLocation, 0);
// Draw the geometry.
var primitiveType = gl.TRIANGLES;
var offset = 0;
gl.drawArrays(primitiveType, offset, numElements);
}
}
// Fill the buffer positions for the head.
function setGeometry(gl) {
var positions = new Float32Array(HeadData.positions);
gl.bufferData(gl.ARRAY_BUFFER, positions, gl.STATIC_DRAW);
return positions.length / 3;
}
// Fill the buffer with normals for the head.
function setNormals(gl, numElements) {
var normals = HeadData.normals;
gl.bufferData(
gl.ARRAY_BUFFER, new Float32Array(normals), gl.STATIC_DRAW);
}
main();
</script>
</html>