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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>
<metacharset="utf-8">
<metaname="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>WebGL - 3D Step 4 - Cull backfaces</title>
<linktype="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<divclass="description">
Drag sliders to translate, rotate, and scale.
</div>
<canvasid="canvas"></canvas>
<divid="uiContainer">
<divid="ui">
<divid="x"></div>
<divid="y"></div>
<divid="z"></div>
<divid="angleX"></div>
<divid="angleY"></div>
<divid="angleZ"></div>
<divid="scaleX"></div>
<divid="scaleY"></div>
<divid="scaleZ"></div>
</div>
</div>
</body>
<!-- vertex shader -->
<scriptid="vertex-shader-3d" type="x-shader/x-vertex">
attributevec4a_position;
attributevec4a_color;
uniformmat4u_matrix;
varyingvec4v_color;
voidmain(){
// Multiply the position by the matrix.
gl_Position=u_matrix*a_position;
// Pass the color to the fragment shader.
v_color=a_color;
}
</script>
<!-- fragment shader -->
<scriptid="fragment-shader-3d" type="x-shader/x-fragment">
precisionmediumpfloat;
// Passed in from the vertex shader.
varyingvec4v_color;
voidmain(){
gl_FragColor=v_color;
}
</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/webgl-lessons-ui.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");
varcolorLocation=gl.getAttribLocation(program,"a_color");
// lookup uniforms
varmatrixLocation=gl.getUniformLocation(program,"u_matrix");
// Create a buffer to put positions in
varpositionBuffer=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
setGeometry(gl);
// Create a buffer to put colors in
varcolorBuffer=gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = colorBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER,colorBuffer);
// Put geometry data into buffer
setColors(gl);
functionradToDeg(r){
returnr*180/Math.PI;
}
functiondegToRad(d){
returnd*Math.PI/180;
}
vartranslation=[45,150,0];
varrotation=[degToRad(40),degToRad(25),degToRad(325)];
varscale=[1,1,1];
drawScene();
// Setup a ui.
webglLessonsUI.setupSlider("#x",{value: translation[0],slide: updatePosition(0),max: gl.canvas.width});
webglLessonsUI.setupSlider("#y",{value: translation[1],slide: updatePosition(1),max: gl.canvas.height});
webglLessonsUI.setupSlider("#z",{value: translation[2],slide: updatePosition(2),max: gl.canvas.height});
webglLessonsUI.setupSlider("#angleX",{value: radToDeg(rotation[0]),slide: updateRotation(0),max: 360});
webglLessonsUI.setupSlider("#angleY",{value: radToDeg(rotation[1]),slide: updateRotation(1),max: 360});
webglLessonsUI.setupSlider("#angleZ",{value: radToDeg(rotation[2]),slide: updateRotation(2),max: 360});
webglLessonsUI.setupSlider("#scaleX",{value: scale[0],slide: updateScale(0),min: -5,max: 5,step: 0.01,precision: 2});
webglLessonsUI.setupSlider("#scaleY",{value: scale[1],slide: updateScale(1),min: -5,max: 5,step: 0.01,precision: 2});
webglLessonsUI.setupSlider("#scaleZ",{value: scale[2],slide: updateScale(2),min: -5,max: 5,step: 0.01,precision: 2});
functionupdatePosition(index){
returnfunction(event,ui){
translation[index]=ui.value;
drawScene();
};
}
functionupdateRotation(index){
returnfunction(event,ui){
varangleInDegrees=ui.value;
varangleInRadians=angleInDegrees*Math.PI/180;
rotation[index]=angleInRadians;
drawScene();
};
}
functionupdateScale(index){
returnfunction(event,ui){
scale[index]=ui.value;
drawScene();
};
}
// Draw the scene.
functiondrawScene(){
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.
gl.clear(gl.COLOR_BUFFER_BIT);
// Turn on culling. By default backfacing triangles
// will be culled.
gl.enable(gl.CULL_FACE);
// 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 color attribute
gl.enableVertexAttribArray(colorLocation);
// Bind the color buffer.
gl.bindBuffer(gl.ARRAY_BUFFER,colorBuffer);
// Tell the attribute how to get data out of colorBuffer (ARRAY_BUFFER)
varsize=3;// 3 components per iteration
vartype=gl.UNSIGNED_BYTE;// the data is 8bit unsigned values
varnormalize=true;// normalize the data (convert from 0-255 to 0-1)
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(
colorLocation,size,type,normalize,stride,offset);
// Compute the matrices
varmatrix=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.
varprimitiveType=gl.TRIANGLES;
varoffset=0;
varcount=16*6;
gl.drawArrays(primitiveType,offset,count);
}
}
varm4={
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){
vara00=a[0*4+0];
vara01=a[0*4+1];
vara02=a[0*4+2];
vara03=a[0*4+3];
vara10=a[1*4+0];
vara11=a[1*4+1];
vara12=a[1*4+2];
vara13=a[1*4+3];
vara20=a[2*4+0];
vara21=a[2*4+1];
vara22=a[2*4+2];
vara23=a[2*4+3];
vara30=a[3*4+0];
vara31=a[3*4+1];
vara32=a[3*4+2];
vara33=a[3*4+3];
varb00=b[0*4+0];
varb01=b[0*4+1];
varb02=b[0*4+2];
varb03=b[0*4+3];
varb10=b[1*4+0];
varb11=b[1*4+1];
varb12=b[1*4+2];
varb13=b[1*4+3];
varb20=b[2*4+0];
varb21=b[2*4+1];
varb22=b[2*4+2];
varb23=b[2*4+3];
varb30=b[3*4+0];
varb31=b[3*4+1];
varb32=b[3*4+2];
varb33=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){
varc=Math.cos(angleInRadians);
vars=Math.sin(angleInRadians);
return[
1,0,0,0,
0,c,s,0,
0,-s,c,0,
0,0,0,1,
];
},
yRotation: function(angleInRadians){
varc=Math.cos(angleInRadians);
vars=Math.sin(angleInRadians);
return[
c,0,-s,0,
0,1,0,0,
s,0,c,0,
0,0,0,1,
];
},
zRotation: function(angleInRadians){
varc=Math.cos(angleInRadians);
vars=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){
returnm4.multiply(m,m4.translation(tx,ty,tz));
},
xRotate: function(m,angleInRadians){
returnm4.multiply(m,m4.xRotation(angleInRadians));
},
yRotate: function(m,angleInRadians){
returnm4.multiply(m,m4.yRotation(angleInRadians));
},
zRotate: function(m,angleInRadians){
returnm4.multiply(m,m4.zRotation(angleInRadians));
},
scale: function(m,sx,sy,sz){
returnm4.multiply(m,m4.scaling(sx,sy,sz));
},
};
// Fill the buffer with the values that define a letter 'F'.
functionsetGeometry(gl){
gl.bufferData(
gl.ARRAY_BUFFER,
newFloat32Array([
// 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 buffer with colors for the 'F'.
functionsetColors(gl){
gl.bufferData(
gl.ARRAY_BUFFER,
newUint8Array([
// 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);
}
main();
</script>
</html>
