webgl-fundamentals/webgl/webgl-attributes-2-shaders-same-data.html at master · gfxfundamentals/webgl-fundamentals · GitHub

Name: webgl-fundamentals/webgl/webgl-attributes-2-shaders-same-data.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 - Attributes - 2 shaders same data</title>
<linktype="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<canvasid="canvas"></canvas>
</body>
<!-- vertex shader -->
<scriptid="vertex-color-vertex-shader" type="x-shader/x-vertex">
attributevec4a_position;
attributevec3a_color;

uniformmat4u_matrix;

varyingvec3v_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="vertex-color-fragment-shader" type="x-shader/x-fragment">
precisionmediumpfloat;

// Passed in from the vertex shader.
varyingvec3v_color;

voidmain(){
gl_FragColor=vec4(v_color,1);
}
</script>
<!-- vertex shader -->
<scriptid="solid-color-vertex-shader" type="x-shader/x-vertex">
attributevec4a_position;

uniformmat4u_matrix;

voidmain(){
// Multiply the position by the matrix.
gl_Position=u_matrix*a_position;
}
</script>
<!-- fragment shader -->
<scriptid="solid-color-fragment-shader" type="x-shader/x-fragment">
precisionmediumpfloat;

uniformvec3u_color;

voidmain(){
gl_FragColor=vec4(u_color,1);
}
</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>
<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 programs
varsolidColorProgram=webglUtils.createProgramFromScripts(
gl,["solid-color-vertex-shader","solid-color-fragment-shader"]);
varvertexColorProgram=webglUtils.createProgramFromScripts(
gl,["vertex-color-vertex-shader","vertex-color-fragment-shader"]);

varsolidColorProgramInfo={
program: solidColorProgram,
attribLocations: {
position: gl.getAttribLocation(solidColorProgram,"a_position"),
},
uniformLocations: {
u_color: gl.getUniformLocation(solidColorProgram,"u_color"),
u_matrix: gl.getUniformLocation(solidColorProgram,"u_matrix"),
},
};

varvertexColorProgramInfo={
program: vertexColorProgram,
attribLocations: {
position: gl.getAttribLocation(vertexColorProgram,"a_position"),
color: gl.getAttribLocation(vertexColorProgram,"a_color"),
},
uniformLocations: {
u_matrix: gl.getUniformLocation(vertexColorProgram,"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 color data into buffer
setColors(gl);

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 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);

functionsetupBufferAndAttributes(programInfo){
// Turn on the position attribute
gl.enableVertexAttribArray(programInfo.attribLocations.position);

// 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(
programInfo.attribLocations.position,size,type,normalize,stride,offset);

if(programInfo.attribLocations.color===undefined){
return;
}

// Turn on the color attribute
gl.enableVertexAttribArray(programInfo.attribLocations.color);

// 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.FLOAT;// the data is 32bit floating point values
varnormalize=false;// 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(
programInfo.attribLocations.color,size,type,normalize,stride,offset);
}

// Compute the projection matrix
varfieldOfViewRadians=50*Math.PI/180;
varaspect=gl.canvas.clientWidth/gl.canvas.clientHeight;
varzNear=0.1;
varzFar=200;
varprojectionMatrix=m4.perspective(fieldOfViewRadians,aspect,zNear,zFar);

// Compute the camera's matrix
varcamera=[4,2,5];
vartarget=[0,0,0];
varup=[0,1,0];
varcameraMatrix=m4.lookAt(camera,target,up);

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

// Compute a view projection matrix
varviewProjectionMatrix=m4.multiply(projectionMatrix,viewMatrix);

// Draw a F at the origin
varworldMatrix=m4.identity();

// Multiply the matrices.
varworldViewProjectionMatrix=m4.multiply(viewProjectionMatrix,worldMatrix);

// Depth test passes if new depth value is less than existing depth value
gl.depthFunc(gl.LESS);

{
// Tell it to use our program (pair of shaders)
gl.useProgram(vertexColorProgramInfo.program);
setupBufferAndAttributes(vertexColorProgramInfo);

// Set the matrix.
gl.uniformMatrix4fv(vertexColorProgramInfo.uniformLocations.u_matrix,false,worldViewProjectionMatrix);

// Draw the geometry.
varprimitiveType=gl.TRIANGLES;
varoffset=0;
varcount=6*6;
gl.drawArrays(primitiveType,offset,count);
}

// Depth test passes if new depth value is less than or equal to existing depth value
gl.depthFunc(gl.LEQUAL);

{
gl.useProgram(solidColorProgramInfo.program);
setupBufferAndAttributes(solidColorProgramInfo);

// Set the matrix.
gl.uniformMatrix4fv(solidColorProgramInfo.uniformLocations.u_matrix,false,worldViewProjectionMatrix);

// Set the color to use
gl.uniform3fv(solidColorProgramInfo.uniformLocations.u_color,[2,2,2]);// white

// Draw the geometry.
varprimitiveType=gl.LINE_STRIP;
varoffset=0;
varcount=6*6;
gl.drawArrays(primitiveType,offset,count);
}
}
}

// Fill the buffer with the values that define a letter 'F'.
functionsetGeometry(gl){
varpositions=newFloat32Array([
-1,-1,1,
1,-1,1,
-1,1,1,
-1,1,1,
1,-1,1,
1,1,1,
1,-1,1,
1,-1,-1,
1,1,1,
1,1,1,
1,-1,-1,
1,1,-1,
1,-1,-1,
-1,-1,-1,
1,1,-1,
1,1,-1,
-1,-1,-1,
-1,1,-1,
-1,-1,-1,
-1,-1,1,
-1,1,-1,
-1,1,-1,
-1,-1,1,
-1,1,1,
1,1,-1,
-1,1,-1,
1,1,1,
1,1,1,
-1,1,-1,
-1,1,1,
1,-1,1,
-1,-1,1,
1,-1,-1,
1,-1,-1,
-1,-1,1,
-1,-1,-1,
]);
gl.bufferData(gl.ARRAY_BUFFER,positions,gl.STATIC_DRAW);
}

functionsetColors(gl){
varcolors=newFloat32Array([
0.25,0.25,0.75,
0.75,0.25,0.75,
0.25,0.75,0.75,
0.25,0.75,0.75,
0.75,0.25,0.75,
0.75,0.75,0.75,
0.75,0.25,0.75,
0.75,0.25,0.25,
0.75,0.75,0.75,
0.75,0.75,0.75,
0.75,0.25,0.25,
0.75,0.75,0.25,
0.75,0.25,0.25,
0.25,0.25,0.25,
0.75,0.75,0.25,
0.75,0.75,0.25,
0.25,0.25,0.25,
0.25,0.75,0.25,
0.25,0.25,0.25,
0.25,0.25,0.75,
0.25,0.75,0.25,
0.25,0.75,0.25,
0.25,0.25,0.75,
0.25,0.75,0.75,
0.75,0.75,0.25,
0.25,0.75,0.25,
0.75,0.75,0.75,
0.75,0.75,0.75,
0.25,0.75,0.25,
0.25,0.75,0.75,
0.75,0.25,0.75,
0.25,0.25,0.75,
0.75,0.25,0.25,
0.75,0.25,0.25,
0.25,0.25,0.75,
0.25,0.25,0.25,
]);
gl.bufferData(gl.ARRAY_BUFFER,colors,gl.STATIC_DRAW);
}

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