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webgl-3d-step4.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>WebGL2 - 3D Step 4 - Cull backfaces</title>
<link type="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<div class="description">
Drag sliders to translate, rotate, and scale.
</div>
<canvas id="canvas" width="400" height="300"></canvas>
<div id="uiContainer">
<div id="ui">
<div id="x"></div>
<div id="y"></div>
<div id="z"></div>
<div id="angleX"></div>
<div id="angleY"></div>
<div id="angleZ"></div>
<div id="scaleX"></div>
<div id="scaleY"></div>
<div id="scaleZ"></div>
</div>
</div>
</body>
<script src="resources/webgl-utils.js"></script>
<script src="resources/webgl-lessons-helper.js"></script>
<script>
"use strict";
var vertexShaderSource = `#version 300 es
// an attribute is an input (in) to a vertex shader.
// It will receive data from a buffer
in vec4 a_position;
in vec4 a_color;
// A matrix to transform the positions by
uniform mat4 u_matrix;
// a varying the color to the fragment shader
out vec4 v_color;
// all shaders have a main function
void main() {
// Multiply the position by the matrix.
gl_Position = u_matrix * a_position;
// Pass the color to the fragment shader.
v_color = a_color;
}
`;
var fragmentShaderSource = `#version 300 es
precision mediump float;
// the varied color passed from the vertex shader
in vec4 v_color;
// we need to declare an output for the fragment shader
out vec4 outColor;
void main() {
outColor = v_color;
}
`;
function main() {
// Get A WebGL context
var canvas = document.getElementById("canvas");
webglLessonsHelper.setupLesson(canvas);
/** @type {WebGLRenderingContext} */
var gl = canvas.getContext("webgl2");
if (!gl) {
webglLessonsHelper.showNeedWebGL2(canvas);
return;
}
// Use our boilerplate utils to compile the shaders and link into a program
var program = webglUtils.createProgramFromSources(gl,
[vertexShaderSource, fragmentShaderSource]);
// look up where the vertex data needs to go.
var positionAttributeLocation = gl.getAttribLocation(program, "a_position");
var colorAttributeLocation = gl.getAttribLocation(program, "a_color");
// look up uniform locations
var matrixLocation = gl.getUniformLocation(program, "u_matrix");
// Create a buffer
var positionBuffer = gl.createBuffer();
// Create a vertex array object (attribute state)
var vao = gl.createVertexArray();
// and make it the one we're currently working with
gl.bindVertexArray(vao);
// Turn on the attribute
gl.enableVertexAttribArray(positionAttributeLocation);
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Set Geometry.
setGeometry(gl);
// Tell the 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(
positionAttributeLocation, size, type, normalize, stride, offset);
// create the color buffer, make it the current ARRAY_BUFFER
// and copy in the color values
var colorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer);
setColors(gl);
// Turn on the attribute
gl.enableVertexAttribArray(colorAttributeLocation);
// Tell the attribute how to get data out of colorBuffer (ARRAY_BUFFER)
var size = 3; // 3 components per iteration
var type = gl.UNSIGNED_BYTE; // the data is 8bit unsigned bytes
var normalize = true; // convert from 0-255 to 0.0-1.0
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next color
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
colorAttributeLocation, size, type, normalize, stride, offset);
function radToDeg(r) {
return r * 180 / Math.PI;
}
function degToRad(d) {
return d * Math.PI / 180;
}
// First let's make some variables
// to hold the translation,
var translation = [45, 150, 0];
var rotation = [degToRad(40), degToRad(25), degToRad(325)];
var scale = [1, 1, 1];
var color = [Math.random(), Math.random(), Math.random(), 1];
drawScene();
// Setup a ui.
webglLessonsHelper.setupSlider("#x", {value: translation[0], slide: updatePosition(0), max: gl.canvas.width });
webglLessonsHelper.setupSlider("#y", {value: translation[1], slide: updatePosition(1), max: gl.canvas.height});
webglLessonsHelper.setupSlider("#z", {value: translation[2], slide: updatePosition(2), max: gl.canvas.height});
webglLessonsHelper.setupSlider("#angleX", {value: radToDeg(rotation[0]), slide: updateRotation(0), max: 360});
webglLessonsHelper.setupSlider("#angleY", {value: radToDeg(rotation[1]), slide: updateRotation(1), max: 360});
webglLessonsHelper.setupSlider("#angleZ", {value: radToDeg(rotation[2]), slide: updateRotation(2), max: 360});
webglLessonsHelper.setupSlider("#scaleX", {value: scale[0], slide: updateScale(0), min: -5, max: 5, step: 0.01, precision: 2});
webglLessonsHelper.setupSlider("#scaleY", {value: scale[1], slide: updateScale(1), min: -5, max: 5, step: 0.01, precision: 2});
webglLessonsHelper.setupSlider("#scaleZ", {value: scale[2], slide: updateScale(2), min: -5, max: 5, step: 0.01, precision: 2});
function updatePosition(index) {
return function(event, ui) {
translation[index] = ui.value;
drawScene();
}
}
function updateRotation(index) {
return function(event, ui) {
var angleInDegrees = ui.value;
var angleInRadians = degToRad(angleInDegrees);
rotation[index] = angleInRadians;
drawScene();
}
}
function updateScale(index) {
return function(event, ui) {
scale[index] = ui.value;
drawScene();
}
}
// Draw the scene.
function drawScene() {
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
// Clear the canvas
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// tell webgl to cull faces
gl.enable(gl.CULL_FACE);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// Bind the attribute/buffer set we want.
gl.bindVertexArray(vao);
// Compute the matrix
var matrix = m4.projection(gl.canvas.clientWidth, gl.canvas.clientHeight, 400);
matrix = m4.translate(matrix, translation[0], translation[1], translation[2]);
matrix = m4.xRotate(matrix, rotation[0]);
matrix = m4.yRotate(matrix, rotation[1]);
matrix = m4.zRotate(matrix, rotation[2]);
matrix = m4.scale(matrix, scale[0], scale[1], scale[2]);
// Set the matrix.
gl.uniformMatrix4fv(matrixLocation, false, matrix);
// Draw the geometry.
var primitiveType = gl.TRIANGLES;
var offset = 0;
var count = 16 * 6;
gl.drawArrays(primitiveType, offset, count);
}
}
// Fill the current ARRAY_BUFFER buffer
// with the values that define a letter 'F'.
function setGeometry(gl) {
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array([
// left column front
0, 0, 0,
30, 0, 0,
0, 150, 0,
0, 150, 0,
30, 0, 0,
30, 150, 0,
// top rung front
30, 0, 0,
100, 0, 0,
30, 30, 0,
30, 30, 0,
100, 0, 0,
100, 30, 0,
// middle rung front
30, 60, 0,
67, 60, 0,
30, 90, 0,
30, 90, 0,
67, 60, 0,
67, 90, 0,
// left column back
0, 0, 30,
30, 0, 30,
0, 150, 30,
0, 150, 30,
30, 0, 30,
30, 150, 30,
// top rung back
30, 0, 30,
100, 0, 30,
30, 30, 30,
30, 30, 30,
100, 0, 30,
100, 30, 30,
// middle rung back
30, 60, 30,
67, 60, 30,
30, 90, 30,
30, 90, 30,
67, 60, 30,
67, 90, 30,
// top
0, 0, 0,
100, 0, 0,
100, 0, 30,
0, 0, 0,
100, 0, 30,
0, 0, 30,
// top rung right
100, 0, 0,
100, 30, 0,
100, 30, 30,
100, 0, 0,
100, 30, 30,
100, 0, 30,
// under top rung
30, 30, 0,
30, 30, 30,
100, 30, 30,
30, 30, 0,
100, 30, 30,
100, 30, 0,
// between top rung and middle
30, 30, 0,
30, 30, 30,
30, 60, 30,
30, 30, 0,
30, 60, 30,
30, 60, 0,
// top of middle rung
30, 60, 0,
30, 60, 30,
67, 60, 30,
30, 60, 0,
67, 60, 30,
67, 60, 0,
// right of middle rung
67, 60, 0,
67, 60, 30,
67, 90, 30,
67, 60, 0,
67, 90, 30,
67, 90, 0,
// bottom of middle rung.
30, 90, 0,
30, 90, 30,
67, 90, 30,
30, 90, 0,
67, 90, 30,
67, 90, 0,
// right of bottom
30, 90, 0,
30, 90, 30,
30, 150, 30,
30, 90, 0,
30, 150, 30,
30, 150, 0,
// bottom
0, 150, 0,
0, 150, 30,
30, 150, 30,
0, 150, 0,
30, 150, 30,
30, 150, 0,
// left side
0, 0, 0,
0, 0, 30,
0, 150, 30,
0, 0, 0,
0, 150, 30,
0, 150, 0,
]),
gl.STATIC_DRAW);
}
// Fill the current ARRAY_BUFFER buffer with colors for the 'F'.
function setColors(gl) {
gl.bufferData(
gl.ARRAY_BUFFER,
new Uint8Array([
// left column front
200, 70, 120,
200, 70, 120,
200, 70, 120,
200, 70, 120,
200, 70, 120,
200, 70, 120,
// top rung front
200, 70, 120,
200, 70, 120,
200, 70, 120,
200, 70, 120,
200, 70, 120,
200, 70, 120,
// middle rung front
200, 70, 120,
200, 70, 120,
200, 70, 120,
200, 70, 120,
200, 70, 120,
200, 70, 120,
// left column back
80, 70, 200,
80, 70, 200,
80, 70, 200,
80, 70, 200,
80, 70, 200,
80, 70, 200,
// top rung back
80, 70, 200,
80, 70, 200,
80, 70, 200,
80, 70, 200,
80, 70, 200,
80, 70, 200,
// middle rung back
80, 70, 200,
80, 70, 200,
80, 70, 200,
80, 70, 200,
80, 70, 200,
80, 70, 200,
// top
70, 200, 210,
70, 200, 210,
70, 200, 210,
70, 200, 210,
70, 200, 210,
70, 200, 210,
// top rung right
200, 200, 70,
200, 200, 70,
200, 200, 70,
200, 200, 70,
200, 200, 70,
200, 200, 70,
// under top rung
210, 100, 70,
210, 100, 70,
210, 100, 70,
210, 100, 70,
210, 100, 70,
210, 100, 70,
// between top rung and middle
210, 160, 70,
210, 160, 70,
210, 160, 70,
210, 160, 70,
210, 160, 70,
210, 160, 70,
// top of middle rung
70, 180, 210,
70, 180, 210,
70, 180, 210,
70, 180, 210,
70, 180, 210,
70, 180, 210,
// right of middle rung
100, 70, 210,
100, 70, 210,
100, 70, 210,
100, 70, 210,
100, 70, 210,
100, 70, 210,
// bottom of middle rung.
76, 210, 100,
76, 210, 100,
76, 210, 100,
76, 210, 100,
76, 210, 100,
76, 210, 100,
// right of bottom
140, 210, 80,
140, 210, 80,
140, 210, 80,
140, 210, 80,
140, 210, 80,
140, 210, 80,
// bottom
90, 130, 110,
90, 130, 110,
90, 130, 110,
90, 130, 110,
90, 130, 110,
90, 130, 110,
// left side
160, 160, 220,
160, 160, 220,
160, 160, 220,
160, 160, 220,
160, 160, 220,
160, 160, 220]),
gl.STATIC_DRAW);
}
var m4 = {
projection: function(width, height, depth) {
// Note: This matrix flips the Y axis so 0 is at the top.
return [
2 / width, 0, 0, 0,
0, -2 / height, 0, 0,
0, 0, 2 / depth, 0,
-1, 1, 0, 1,
];
},
multiply: function(a, b) {
var a00 = a[0*4+0];
var a01 = a[0*4+1];
var a02 = a[0*4+2];
var a03 = a[0*4+3];
var a10 = a[1*4+0];
var a11 = a[1*4+1];
var a12 = a[1*4+2];
var a13 = a[1*4+3];
var a20 = a[2*4+0];
var a21 = a[2*4+1];
var a22 = a[2*4+2];
var a23 = a[2*4+3];
var a30 = a[3*4+0];
var a31 = a[3*4+1];
var a32 = a[3*4+2];
var a33 = a[3*4+3];
var b00 = b[0*4+0];
var b01 = b[0*4+1];
var b02 = b[0*4+2];
var b03 = b[0*4+3];
var b10 = b[1*4+0];
var b11 = b[1*4+1];
var b12 = b[1*4+2];
var b13 = b[1*4+3];
var b20 = b[2*4+0];
var b21 = b[2*4+1];
var b22 = b[2*4+2];
var b23 = b[2*4+3];
var b30 = b[3*4+0];
var b31 = b[3*4+1];
var b32 = b[3*4+2];
var b33 = b[3*4+3];
return [
b00 * a00 + b01 * a10 + b02 * a20 + b03 * a30,
b00 * a01 + b01 * a11 + b02 * a21 + b03 * a31,
b00 * a02 + b01 * a12 + b02 * a22 + b03 * a32,
b00 * a03 + b01 * a13 + b02 * a23 + b03 * a33,
b10 * a00 + b11 * a10 + b12 * a20 + b13 * a30,
b10 * a01 + b11 * a11 + b12 * a21 + b13 * a31,
b10 * a02 + b11 * a12 + b12 * a22 + b13 * a32,
b10 * a03 + b11 * a13 + b12 * a23 + b13 * a33,
b20 * a00 + b21 * a10 + b22 * a20 + b23 * a30,
b20 * a01 + b21 * a11 + b22 * a21 + b23 * a31,
b20 * a02 + b21 * a12 + b22 * a22 + b23 * a32,
b20 * a03 + b21 * a13 + b22 * a23 + b23 * a33,
b30 * a00 + b31 * a10 + b32 * a20 + b33 * a30,
b30 * a01 + b31 * a11 + b32 * a21 + b33 * a31,
b30 * a02 + b31 * a12 + b32 * a22 + b33 * a32,
b30 * a03 + b31 * a13 + b32 * a23 + b33 * a33,
];
},
translation: function(tx, ty, tz) {
return [
1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
tx, ty, tz, 1,
];
},
xRotation: function(angleInRadians) {
var c = Math.cos(angleInRadians);
var s = Math.sin(angleInRadians);
return [
1, 0, 0, 0,
0, c, s, 0,
0, -s, c, 0,
0, 0, 0, 1,
];
},
yRotation: function(angleInRadians) {
var c = Math.cos(angleInRadians);
var s = Math.sin(angleInRadians);
return [
c, 0, -s, 0,
0, 1, 0, 0,
s, 0, c, 0,
0, 0, 0, 1,
];
},
zRotation: function(angleInRadians) {
var c = Math.cos(angleInRadians);
var s = Math.sin(angleInRadians);
return [
c, s, 0, 0,
-s, c, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1,
];
},
scaling: function(sx, sy, sz) {
return [
sx, 0, 0, 0,
0, sy, 0, 0,
0, 0, sz, 0,
0, 0, 0, 1,
];
},
translate: function(m, tx, ty, tz) {
return m4.multiply(m, m4.translation(tx, ty, tz));
},
xRotate: function(m, angleInRadians) {
return m4.multiply(m, m4.xRotation(angleInRadians));
},
yRotate: function(m, angleInRadians) {
return m4.multiply(m, m4.yRotation(angleInRadians));
},
zRotate: function(m, angleInRadians) {
return m4.multiply(m, m4.zRotation(angleInRadians));
},
scale: function(m, sx, sy, sz) {
return m4.multiply(m, m4.scaling(sx, sy, sz));
},
};
main();
</script>
</html>