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webgl-2d-matrixstack-03.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 - 2D - DrawImage with MatrixStack images at 4 corners</title>
<link type="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<canvas id="canvas" width="400" height="300"></canvas>
</body>
<script src="resources/webgl-utils.js"></script>
<script src="resources/webgl-lessons-helper.js"></script>
<script src="resources/3d-math.js"></script>
<script>
"use strict";
var vertexShaderSource = `#version 300 es
in vec4 a_position;
in vec2 a_texcoord;
uniform mat4 u_matrix;
uniform mat4 u_textureMatrix;
out vec2 v_texcoord;
void main() {
gl_Position = u_matrix * a_position;
v_texcoord = (u_textureMatrix * vec4(a_texcoord, 0, 1)).xy;
}
`;
var fragmentShaderSource = `#version 300 es
precision mediump float;
in vec2 v_texcoord;
uniform sampler2D u_texture;
out vec4 outColor;
void main() {
outColor = texture(u_texture, v_texcoord);
}
`;
function MatrixStack() {
this.stack = [];
// since the stack is empty this will put an initial matrix in it
this.restore();
}
// Pops the top of the stack restoring the previously saved matrix
MatrixStack.prototype.restore = function() {
this.stack.pop();
// Never let the stack be totally empty
if (this.stack.length < 1) {
this.stack[0] = m4.identity();
}
};
// Pushes a copy of the current matrix on the stack
MatrixStack.prototype.save = function() {
this.stack.push(this.getCurrentMatrix());
};
// Gets a copy of the current matrix (top of the stack)
MatrixStack.prototype.getCurrentMatrix = function() {
return this.stack[this.stack.length - 1].slice(); // makes a copy
};
// Lets us set the current matrix
MatrixStack.prototype.setCurrentMatrix = function(m) {
return this.stack[this.stack.length - 1] = m;
};
// Translates the current matrix
MatrixStack.prototype.translate = function(x, y, z) {
if (z === undefined) {
z = 0;
}
var m = this.getCurrentMatrix();
this.setCurrentMatrix(m4.translate(m, x, y, z));
};
// Rotates the current matrix around Z
MatrixStack.prototype.rotateZ = function(angleInRadians) {
var m = this.getCurrentMatrix();
this.setCurrentMatrix(m4.zRotate(m, angleInRadians));
};
// Scales the current matrix
MatrixStack.prototype.scale = function(x, y, z) {
if (z === undefined) {
z = 1;
}
var m = this.getCurrentMatrix();
this.setCurrentMatrix(m4.scale(m, x, y, z));
};
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;
}
var matrixStack = new MatrixStack();
// 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 texcoordAttributeLocation = gl.getAttribLocation(program, "a_texcoord");
// lookup uniforms
var matrixLocation = gl.getUniformLocation(program, "u_matrix");
var textureLocation = gl.getUniformLocation(program, "u_texture");
var textureMatrixLocation = gl.getUniformLocation(program, "u_textureMatrix");
// Create a vertex array object (attribute state)
var vao = gl.createVertexArray();
// and make it the one we're currently working with
gl.bindVertexArray(vao);
// create the position buffer, make it the current ARRAY_BUFFER
// and copy in the color values
var positionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Put a unit quad in the buffer
var positions = [
0, 0,
0, 1,
1, 0,
1, 0,
0, 1,
1, 1,
]
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);
// Turn on the attribute
gl.enableVertexAttribArray(positionAttributeLocation);
// Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 2; // 2 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 texcoord buffer, make it the current ARRAY_BUFFER
// and copy in the texcoord values
var texcoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);
// Put texcoords in the buffer
var texcoords = [
0, 0,
0, 1,
1, 0,
1, 0,
0, 1,
1, 1,
]
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(texcoords), gl.STATIC_DRAW);
// Turn on the attribute
gl.enableVertexAttribArray(texcoordAttributeLocation);
// Tell the attribute how to get data out of colorBuffer (ARRAY_BUFFER)
var size = 2; // 3 components per iteration
var type = gl.FLOAT; // the data is 32bit floats
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(
texcoordAttributeLocation, size, type, normalize, stride, offset);
// creates a texture info { width: w, height: h, texture: tex }
// The texture will start with 1x1 pixels and be updated
// when the image has loaded
function loadImageAndCreateTextureInfo(url) {
var tex = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, tex);
// 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]));
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);
var textureInfo = {
width: 1, // we don't know the size until it loads
height: 1,
texture: tex,
};
var img = new Image();
img.addEventListener('load', function() {
textureInfo.width = img.width;
textureInfo.height = img.height;
gl.bindTexture(gl.TEXTURE_2D, textureInfo.texture);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, img);
gl.generateMipmap(gl.TEXTURE_2D);
});
img.src = url;
return textureInfo;
}
var textureInfo = loadImageAndCreateTextureInfo('resources/star.jpg');
function draw(time) {
// 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);
matrixStack.save();
matrixStack.translate(gl.canvas.width / 2, gl.canvas.height / 2);
matrixStack.rotateZ(time);
matrixStack.save();
{
matrixStack.translate(textureInfo.width / -2, textureInfo.height / -2);
drawImage(
textureInfo.texture,
textureInfo.width,
textureInfo.height,
0, 0);
}
matrixStack.restore();
matrixStack.save();
{
// We're at the center of the center image so go to the top/left corner
matrixStack.translate(textureInfo.width / -2, textureInfo.height / -2);
matrixStack.rotateZ(Math.sin(time * 2.2));
matrixStack.scale(0.2, 0.2);
// Now we want the bottom/right corner of the image we're about to draw
matrixStack.translate(-textureInfo.width, -textureInfo.height);
drawImage(
textureInfo.texture,
textureInfo.width,
textureInfo.height,
0, 0);
}
matrixStack.restore();
matrixStack.save();
{
// We're at the center of the center image so go to the top/right corner
matrixStack.translate(textureInfo.width / 2, textureInfo.height / -2);
matrixStack.rotateZ(Math.sin(time * 2.3));
matrixStack.scale(0.2, 0.2);
// Now we want the bottom/right corner of the image we're about to draw
matrixStack.translate(0, -textureInfo.height);
drawImage(
textureInfo.texture,
textureInfo.width,
textureInfo.height,
0, 0);
}
matrixStack.restore();
matrixStack.save();
{
// We're at the center of the center image so go to the bottom/left corner
matrixStack.translate(textureInfo.width / -2, textureInfo.height / 2);
matrixStack.rotateZ(Math.sin(time * 2.4));
matrixStack.scale(0.2, 0.2);
// Now we want the top/right corner of the image we're about to draw
matrixStack.translate(-textureInfo.width, 0);
drawImage(
textureInfo.texture,
textureInfo.width,
textureInfo.height,
0, 0);
}
matrixStack.restore();
matrixStack.save();
{
// We're at the center of the center image so go to the bottom/right corner
matrixStack.translate(textureInfo.width / 2, textureInfo.height / 2);
matrixStack.rotateZ(Math.sin(time * 2.5));
matrixStack.scale(0.2, 0.2);
// Now we want the top/left corner of the image we're about to draw
matrixStack.translate(0, 0); // 0,0 means this line is not really doing anything
drawImage(
textureInfo.texture,
textureInfo.width,
textureInfo.height,
0, 0);
}
matrixStack.restore();
matrixStack.restore();
}
var then = 0;
function render(time) {
time *= 0.001;
draw(time);
requestAnimationFrame(render);
}
requestAnimationFrame(render);
// Unlike images, textures do not have a width and height associated
// with them so we'll pass in the width and height of the texture
function drawImage(
tex, texWidth, texHeight,
srcX, srcY, srcWidth, srcHeight,
dstX, dstY, dstWidth, dstHeight) {
if (dstX === undefined) {
dstX = srcX;
}
if (dstY === undefined) {
dstY = srcY;
}
if (srcWidth === undefined) {
srcWidth = texWidth;
}
if (srcHeight === undefined) {
srcHeight = texHeight;
}
if (dstWidth === undefined) {
dstWidth = srcWidth;
}
if (dstHeight === undefined) {
dstHeight = srcHeight;
}
gl.useProgram(program);
// Setup the attributes for the quad
gl.bindVertexArray(vao);
var textureUnit = 0;
// The the shader we're putting the texture on texture unit 0
gl.uniform1i(textureLocation, textureUnit);
// Bind the texture to texture unit 0
gl.activeTexture(gl.TEXTURE0 + textureUnit);
gl.bindTexture(gl.TEXTURE_2D, tex);
// this matirx will convert from pixels to clip space
var matrix = m4.orthographic(
0, gl.canvas.clientWidth, gl.canvas.clientHeight, 0, -1, 1);
// The matrix stack is in pixels so it goes after the projection
// above which converted our space from clip space to pixel space
matrix = m4.multiply(matrix, matrixStack.getCurrentMatrix());
// translate our quad to dstX, dstY
matrix = m4.translate(matrix, dstX, dstY, 0);
// scale our 1 unit quad
// from 1 unit to dstWidth, dstHeight units
matrix = m4.scale(matrix, dstWidth, dstHeight, 1);
// Set the matrix.
gl.uniformMatrix4fv(matrixLocation, false, matrix);
// Because texture coordinates go from 0 to 1
// and because our texture coordinates are already a unit quad
// we can select an area of the texture by scaling the unit quad
// down
var texMatrix = m4.translation(srcX / texWidth, srcY / texHeight, 0);
texMatrix = m4.scale(texMatrix, srcWidth / texWidth, srcHeight / texHeight, 1);
// Set the texture matrix.
gl.uniformMatrix4fv(textureMatrixLocation, false, texMatrix);
// draw the quad (2 triangles, 6 vertices)
var offset = 0;
var count = 6;
gl.drawArrays(gl.TRIANGLES, offset, count);
}
}
main();
</script>
</html>