webgl-fundamentals/webgl/webgl-3d-textures-texture-atlas.html at master · gfxfundamentals/webgl-fundamentals · GitHub

Name: webgl-fundamentals/webgl/webgl-3d-textures-texture-atlas.html at master · gfxfundamentals/webgl-fundamentals · GitHub
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<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
<head>
<metacharset="utf-8">
<metaname="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>WebGL - Textures - Texture Atlas</title>
<linktype="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<divclass="description">
Textured Cube with a different image on each face using a texture altas. <br/>
</div>
<canvasid="canvas"></canvas>
</body>
<!-- vertex shader -->
<scriptid="vertex-shader-3d" type="x-shader/x-vertex">
attributevec4a_position;
attributevec2a_texcoord;

uniformmat4u_matrix;

varyingvec2v_texcoord;

voidmain(){
// Multiply the position by the matrix.
gl_Position=u_matrix*a_position;

// Pass the texcoord to the fragment shader.
v_texcoord=a_texcoord;
}
</script>
<!-- fragment shader -->
<scriptid="fragment-shader-3d" type="x-shader/x-fragment">
precisionmediumpfloat;

// Passed in from the vertex shader.
varyingvec2v_texcoord;

// The texture.
uniformsampler2Du_texture;

voidmain(){
gl_FragColor=texture2D(u_texture,v_texcoord);
}
</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.
-->
<scriptsrc="resources/webgl-utils.js"></script>
<scriptsrc="resources/m4.js"></script>
<script>
"use strict";

functionmain(){
// Get A WebGL context
/** @type {HTMLCanvasElement} */
varcanvas=document.querySelector("#canvas");
vargl=canvas.getContext("webgl");
if(!gl){
return;
}

// setup GLSL program
varprogram=webglUtils.createProgramFromScripts(gl,["vertex-shader-3d","fragment-shader-3d"]);

// look up where the vertex data needs to go.
varpositionLocation=gl.getAttribLocation(program,"a_position");
vartexcoordLocation=gl.getAttribLocation(program,"a_texcoord");

// lookup uniforms
varmatrixLocation=gl.getUniformLocation(program,"u_matrix");
vartextureLocation=gl.getUniformLocation(program,"u_texture");

// Create a buffer for positions
varpositionBuffer=gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER,positionBuffer);
// Put the positions in the buffer
setGeometry(gl);

// provide texture coordinates for the rectangle.
vartexcoordBuffer=gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER,texcoordBuffer);
// Set Texcoords.
setTexcoords(gl);

// Create a texture.
vartexture=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,
newUint8Array([0,0,255,255]));
// Asynchronously load an image
varimage=newImage();
image.src="resources/noodles.jpg";
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);

// Check if the image is a power of 2 in both dimensions.
if(isPowerOf2(image.width)&&isPowerOf2(image.height)){
// Yes, it's a power of 2. Generate mips.
gl.generateMipmap(gl.TEXTURE_2D);
}else{
// No, it's not a power of 2. Turn of mips and set wrapping to clamp to edge
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.LINEAR);
}
});

functionisPowerOf2(value){
return(value&(value-1))===0;
}

functionradToDeg(r){
returnr*180/Math.PI;
}

functiondegToRad(d){
returnd*Math.PI/180;
}

varfieldOfViewRadians=degToRad(60);
varmodelXRotationRadians=degToRad(0);
varmodelYRotationRadians=degToRad(0);

// Get the starting time.
varthen=0;

requestAnimationFrame(drawScene);

// Draw the scene.
functiondrawScene(time){
// convert to seconds
time*=0.001;
// Subtract the previous time from the current time
vardeltaTime=time-then;
// Remember the current time for the next frame.
then=time;

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);

// Animate the rotation
modelYRotationRadians+=-0.7*deltaTime;
modelXRotationRadians+=-0.4*deltaTime;

// Clear the canvas AND the depth buffer.
gl.clear(gl.COLOR_BUFFER_BIT|gl.DEPTH_BUFFER_BIT);

// 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)
varsize=3;// 3 components per iteration
vartype=gl.FLOAT;// the data is 32bit floats
varnormalize=false;// don't normalize the data
varstride=0;// 0 = move forward size * sizeof(type) each iteration to get the next position
varoffset=0;// start at the beginning of the buffer
gl.vertexAttribPointer(
positionLocation,size,type,normalize,stride,offset);

// Turn on the texcoord attribute
gl.enableVertexAttribArray(texcoordLocation);

// bind the texcoord buffer.
gl.bindBuffer(gl.ARRAY_BUFFER,texcoordBuffer);

// Tell the texcoord attribute how to get data out of texcoordBuffer (ARRAY_BUFFER)
varsize=2;// 2 components per iteration
vartype=gl.FLOAT;// the data is 32bit floats
varnormalize=false;// don't normalize the data
varstride=0;// 0 = move forward size * sizeof(type) each iteration to get the next position
varoffset=0;// start at the beginning of the buffer
gl.vertexAttribPointer(
texcoordLocation,size,type,normalize,stride,offset);

// Compute the projection matrix
varaspect=gl.canvas.clientWidth/gl.canvas.clientHeight;
varprojectionMatrix=
m4.perspective(fieldOfViewRadians,aspect,1,2000);

varcameraPosition=[0,0,2];
varup=[0,1,0];
vartarget=[0,0,0];

// Compute the camera's matrix using look at.
varcameraMatrix=m4.lookAt(cameraPosition,target,up);

// Make a view matrix from the camera matrix.
varviewMatrix=m4.inverse(cameraMatrix);

varviewProjectionMatrix=m4.multiply(projectionMatrix,viewMatrix);

varmatrix=m4.xRotate(viewProjectionMatrix,modelXRotationRadians);
matrix=m4.yRotate(matrix,modelYRotationRadians);

// Set the matrix.
gl.uniformMatrix4fv(matrixLocation,false,matrix);

// Tell the shader to use texture unit 0 for u_texture
gl.uniform1i(textureLocation,0);

// Draw the geometry.
gl.drawArrays(gl.TRIANGLES,0,6*6);

requestAnimationFrame(drawScene);
}
}

// Fill the buffer with the values that define a cube.
functionsetGeometry(gl){
varpositions=newFloat32Array(
[
-0.5,-0.5,-0.5,
-0.5,0.5,-0.5,
0.5,-0.5,-0.5,
-0.5,0.5,-0.5,
0.5,0.5,-0.5,
0.5,-0.5,-0.5,

-0.5,-0.5,0.5,
0.5,-0.5,0.5,
-0.5,0.5,0.5,
-0.5,0.5,0.5,
0.5,-0.5,0.5,
0.5,0.5,0.5,

-0.5,0.5,-0.5,
-0.5,0.5,0.5,
0.5,0.5,-0.5,
-0.5,0.5,0.5,
0.5,0.5,0.5,
0.5,0.5,-0.5,

-0.5,-0.5,-0.5,
0.5,-0.5,-0.5,
-0.5,-0.5,0.5,
-0.5,-0.5,0.5,
0.5,-0.5,-0.5,
0.5,-0.5,0.5,

-0.5,-0.5,-0.5,
-0.5,-0.5,0.5,
-0.5,0.5,-0.5,
-0.5,-0.5,0.5,
-0.5,0.5,0.5,
-0.5,0.5,-0.5,

0.5,-0.5,-0.5,
0.5,0.5,-0.5,
0.5,-0.5,0.5,
0.5,-0.5,0.5,
0.5,0.5,-0.5,
0.5,0.5,0.5,

]);
gl.bufferData(gl.ARRAY_BUFFER,positions,gl.STATIC_DRAW);
}

// Fill the buffer with texture coordinates the cube.
functionsetTexcoords(gl){
gl.bufferData(
gl.ARRAY_BUFFER,
newFloat32Array(
[
// select the top left image
0,0,
0,0.5,
0.25,0,
0,0.5,
0.25,0.5,
0.25,0,
// select the top middle image
0.25,0,
0.5,0,
0.25,0.5,
0.25,0.5,
0.5,0,
0.5,0.5,
// select to top right image
0.5,0,
0.5,0.5,
0.75,0,
0.5,0.5,
0.75,0.5,
0.75,0,
// select the bottom left image
0,0.5,
0.25,0.5,
0,1,
0,1,
0.25,0.5,
0.25,1,
// select the bottom middle image
0.25,0.5,
0.25,1,
0.5,0.5,
0.25,1,
0.5,1,
0.5,0.5,
// select the bottom right image
0.5,0.5,
0.75,0.5,
0.5,1,
0.5,1,
0.75,0.5,
0.75,1,

]),
gl.STATIC_DRAW);
}

main();
</script>
</html>