How to get a "Glow" shader effect in OpenGL ES 2.0?

Question

I'm writing a 3D app for iOS. I'm new to OpenGL ES 2.0, so I'm still getting myself around writing basic shaders. I really need to implement a "Glow" effect on some of my models, based on the texturing.

Here's a sample:

.

I'm looking for code examples for OpenGL ES 2.0. Most code I find on the internet is either for desktop OpenGL or D3D.

Any ideas?

Answer 1

First of all there are tons of algorithms and techniques to generate a glow effect. I just want to present one possibility.

Create a Material that is luminescent. For this I use a modified Blinn-Phong light model, where the direction to the light source is always the inverse direction of the normal vector of the fragment.

varying vec3 vertPos; varying vec3 vertNV; varying vec3 vertCol;  uniform float u_glow;  void main() {     vec3 color = vertCol;      float shininess = 10.0;     vec3  normalV = normalize( vertNV );     vec3  eyeV    = normalize( -vertPos );     vec3  halfV   = normalize( eyeV + normalV );     float NdotH   = max( 0.0, dot( normalV, halfV ) );     float glowFac = ( shininess + 2.0 ) * pow( NdotH, shininess ) / ( 2.0 * 3.14159265 );      gl_FragColor = vec4( u_glow * (0.1 + color.rgb * glowFac * 0.5), 1.0 ); } 

In a second step a gaussian blur algorithm is performed on the output. The scene is written to frame buffer with a texture bound to the color plane. A screen space pass uses the texture as the input to blur the output.
For performance reasons, the blur algorithm is first performed along the X-axis of the viewport and in a further step along the Y-axis of the viewport.

varying vec2 vertPos; uniform sampler2D u_textureCol; uniform vec2 u_textureSize; uniform float u_sigma; uniform int u_width;  float CalcGauss( float x, float sigma )  {   float coeff = 1.0 / (2.0 * 3.14157 * sigma);   float expon = -(x*x) / (2.0 * sigma);   return (coeff*exp(expon)); }  void main() {     vec2 texC = vertPos.st * 0.5 + 0.5;     vec4 texCol = texture( u_textureCol, texC );     vec4 gaussCol = vec4( texCol.rgb, 1.0 );     vec2 step = 1.0 / u_textureSize;     for ( int i = 1; i <= u_width; ++ i )     {         vec2 actStep = vec2( float(i) * step.x, 0.0 );   // this is for the X-axis         // vec2 actStep = vec2( 0.0, float(i) * step.y );   this would be for the Y-axis          float weight = CalcGauss( float(i) / float(u_width), u_sigma );         texCol = texture2D( u_textureCol, texC + actStep );             gaussCol += vec4( texCol.rgb * weight, weight );         texCol = texture2D( u_textureCol, texC - actStep );         gaussCol += vec4( texCol.rgb * weight, weight );     }     gaussCol.rgb /= gaussCol.w;     gl_FragColor = vec4( gaussCol.rgb, 1.0 ); } 

For the implementation of a blur algorithm see also the answer to the questions:

• OpenGL es 2.0 Gaussian blur on triangle
• What kind of blurs can be implemented in pixel shaders?

See the following similar WebGL example which puts all together:

var readInput = true; function changeEventHandler(event){     readInput = true; }    (function loadscene() {      var resize, gl, progDraw, progBlurX, progPost, vp_size, blurFB;   var bufCube = {};   var bufQuad = {};   var shininess = 10.0;   var glow = 10.0;   var sigma = 0.8;      function render(delteMS){        //if ( readInput ) {           readInput = false;           var sliderScale = 100;           shininess = document.getElementById( "shine" ).value;           glow      = document.getElementById( "glow" ).value / sliderScale;           sigma     = document.getElementById( "sigma" ).value / sliderScale;       //}        Camera.create();       Camera.vp = vp_size;                  gl.enable( gl.DEPTH_TEST );       gl.clearColor( 0.0, 0.0, 0.0, 1.0 );       gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );        // set up framebuffer       gl.bindFramebuffer( gl.FRAMEBUFFER, blurFB[0] );       gl.viewport( 0, 0, blurFB[0].width, blurFB[0].height );       gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );          // set up draw shader       ShaderProgram.Use( progDraw.prog );       ShaderProgram.SetUniformM44( progDraw.prog, "u_projectionMat44", Camera.Perspective() );       ShaderProgram.SetUniformM44( progDraw.prog, "u_viewMat44", Camera.LookAt() );       var modelMat = IdentityMat44()       modelMat = RotateAxis( modelMat, CalcAng( delteMS, 13.0 ), 0 );       modelMat = RotateAxis( modelMat, CalcAng( delteMS, 17.0 ), 1 );       ShaderProgram.SetUniformM44( progDraw.prog, "u_modelMat44", modelMat );       ShaderProgram.SetUniformF1( progDraw.prog, "u_shininess", shininess );       ShaderProgram.SetUniformF1( progDraw.prog, "u_glow", glow );              // draw scene       VertexBuffer.Draw( bufCube );        // set blur-X framebuffer and bind frambuffer texture       gl.bindFramebuffer( gl.FRAMEBUFFER, blurFB[1] );       gl.viewport( 0, 0, blurFB[1].width, blurFB[1].height );       gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );       var texUnit = 1;       gl.activeTexture( gl.TEXTURE0 + texUnit );       gl.bindTexture( gl.TEXTURE_2D, blurFB[0].color0_texture );        // set up blur-X shader       ShaderProgram.Use( progBlurX.prog );       ShaderProgram.SetUniformI1( progBlurX.prog , "u_texture", texUnit )       ShaderProgram.SetUniformF2( progBlurX.prog , "u_textureSize", vp_size );       ShaderProgram.SetUniformF1( progBlurX.prog , "u_sigma", sigma )        // draw full screen space       gl.enableVertexAttribArray( progBlurX.inPos );       gl.bindBuffer( gl.ARRAY_BUFFER, bufQuad.pos );       gl.vertexAttribPointer( progBlurX.inPos, 2, gl.FLOAT, false, 0, 0 );        gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufQuad.inx );       gl.drawElements( gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0 );       gl.disableVertexAttribArray( progBlurX.inPos );        // reset framebuffer and bind frambuffer texture       gl.bindFramebuffer( gl.FRAMEBUFFER, null );       gl.viewport( 0, 0, vp_size[0], vp_size[1] );       gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );       texUnit = 2;       gl.activeTexture( gl.TEXTURE0 + texUnit );       gl.bindTexture( gl.TEXTURE_2D, blurFB[1].color0_texture );        // set up pst process shader       ShaderProgram.Use( progPost.prog );       ShaderProgram.SetUniformI1( progPost.prog, "u_texture", texUnit )       ShaderProgram.SetUniformF2( progPost.prog, "u_textureSize", vp_size );       ShaderProgram.SetUniformF1( progPost.prog, "u_sigma", sigma );        // draw full screen space       gl.enableVertexAttribArray( progPost.inPos );       gl.bindBuffer( gl.ARRAY_BUFFER, bufQuad.pos );       gl.vertexAttribPointer( progPost.inPos, 2, gl.FLOAT, false, 0, 0 );        gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufQuad.inx );       gl.drawElements( gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0 );       gl.disableVertexAttribArray( progPost.inPos );        requestAnimationFrame(render);   }      function resize() {       //vp_size = [gl.drawingBufferWidth, gl.drawingBufferHeight];       vp_size = [window.innerWidth, window.innerHeight]       canvas.width = vp_size[0];       canvas.height = vp_size[1];        var fbsize = Math.max(vp_size[0], vp_size[1])-1;       fbsize = 1 << 31 - Math.clz32(fbsize); // nearest power of 2       fbsize = fbsize * 2        blurFB = [];       for ( var i = 0; i < 2; ++ i ) {           fb = gl.createFramebuffer();           fb.width = fbsize;           fb.height = fbsize;           gl.bindFramebuffer( gl.FRAMEBUFFER, fb );           fb.color0_texture = gl.createTexture();           gl.bindTexture( gl.TEXTURE_2D, fb.color0_texture );           gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST );           gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST );           gl.texImage2D( gl.TEXTURE_2D, 0, gl.RGBA, fb.width, fb.height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null );           fb.renderbuffer = gl.createRenderbuffer();           gl.bindRenderbuffer( gl.RENDERBUFFER, fb.renderbuffer );           gl.renderbufferStorage( gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, fb.width, fb.height );           gl.framebufferTexture2D( gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, fb.color0_texture, 0 );           gl.framebufferRenderbuffer( gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, fb.renderbuffer );           gl.bindTexture( gl.TEXTURE_2D, null );           gl.bindRenderbuffer( gl.RENDERBUFFER, null );           gl.bindFramebuffer( gl.FRAMEBUFFER, null );           blurFB.push( fb );       }   }      function initScene() {          canvas = document.getElementById( "canvas");       gl = canvas.getContext( "experimental-webgl" );       if ( !gl )         return null;          progDraw = {}       progDraw.prog = ShaderProgram.Create(          [ { source : "draw-shader-vs", stage : gl.VERTEX_SHADER },           { source : "draw-shader-fs", stage : gl.FRAGMENT_SHADER }         ] );       if ( !progDraw.prog )           return null;       progDraw.inPos = gl.getAttribLocation( progDraw.prog, "inPos" );       progDraw.inNV  = gl.getAttribLocation( progDraw.prog, "inNV" );       progDraw.inCol = gl.getAttribLocation( progDraw.prog, "inCol" );        progBlurX = {}       progBlurX.prog = ShaderProgram.Create(          [ { source : "post-shader-vs", stage : gl.VERTEX_SHADER },           { source : "blurX-shader-fs", stage : gl.FRAGMENT_SHADER }         ] );       progBlurX.inPos = gl.getAttribLocation( progBlurX.prog, "inPos" );       if ( !progBlurX.prog )           return;            progPost = {}       progPost.prog = ShaderProgram.Create(          [ { source : "post-shader-vs", stage : gl.VERTEX_SHADER },           { source : "blurY-shader-fs", stage : gl.FRAGMENT_SHADER }         ] );       progPost.inPos = gl.getAttribLocation( progPost.prog, "inPos" );       if ( !progPost.prog )           return;              // create cube       var cubePos = [         -1.0, -1.0,  1.0,  1.0, -1.0,  1.0,  1.0,  1.0,  1.0, -1.0,  1.0,  1.0,         -1.0, -1.0, -1.0,  1.0, -1.0, -1.0,  1.0,  1.0, -1.0, -1.0,  1.0, -1.0 ];       var cubeCol = [ 1.0, 0.0, 0.0, 1.0, 0.5, 0.0, 1.0, 0.0, 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0 ];       var cubeHlpInx = [ 0, 1, 2, 3, 1, 5, 6, 2, 5, 4, 7, 6, 4, 0, 3, 7, 3, 2, 6, 7, 1, 0, 4, 5 ];         var cubePosData = [];       for ( var i = 0; i < cubeHlpInx.length; ++ i ) {         cubePosData.push( cubePos[cubeHlpInx[i]*3], cubePos[cubeHlpInx[i]*3+1], cubePos[cubeHlpInx[i]*3+2] );       }       var cubeNVData = [];       for ( var i1 = 0; i1 < cubeHlpInx.length; i1 += 4 ) {       var nv = [0, 0, 0];       for ( i2 = 0; i2 < 4; ++ i2 ) {           var i = i1 + i2;           nv[0] += cubePosData[i*3]; nv[1] += cubePosData[i*3+1]; nv[2] += cubePosData[i*3+2];       }       for ( i2 = 0; i2 < 4; ++ i2 )         cubeNVData.push( nv[0], nv[1], nv[2] );       }       var cubeColData = [];       for ( var is = 0; is < 6; ++ is ) {         for ( var ip = 0; ip < 4; ++ ip ) {          cubeColData.push( cubeCol[is*3], cubeCol[is*3+1], cubeCol[is*3+2] );          }       }       var cubeInxData = [];       for ( var i = 0; i < cubeHlpInx.length; i += 4 ) {         cubeInxData.push( i, i+1, i+2, i, i+2, i+3 );          }       bufCube = VertexBuffer.Create(       [ { data : cubePosData, attrSize : 3, attrLoc : progDraw.inPos },         { data : cubeNVData,  attrSize : 3, attrLoc : progDraw.inNV },         { data : cubeColData, attrSize : 3, attrLoc : progDraw.inCol } ],         cubeInxData );        bufQuad.pos = gl.createBuffer();       gl.bindBuffer( gl.ARRAY_BUFFER, bufQuad.pos );       gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( [ -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0 ] ), gl.STATIC_DRAW );       bufQuad.inx = gl.createBuffer();       gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufQuad.inx );       gl.bufferData( gl.ELEMENT_ARRAY_BUFFER, new Uint16Array( [ 0, 1, 2, 0, 2, 3 ] ), gl.STATIC_DRAW );                  window.onresize = resize;       resize();       requestAnimationFrame(render);   }      function Fract( val ) {        return val - Math.trunc( val );   }   function CalcAng( deltaTime, intervall ) {       return Fract( deltaTime / (1000*intervall) ) * 2.0 * Math.PI;   }   function CalcMove( deltaTime, intervall, range ) {       var pos = self.Fract( deltaTime / (1000*intervall) ) * 2.0       var pos = pos < 1.0 ? pos : (2.0-pos)       return range[0] + (range[1] - range[0]) * pos;   }       function EllipticalPosition( a, b, angRag ) {       var a_b = a * a - b * b       var ea = (a_b <= 0) ? 0 : Math.sqrt( a_b );       var eb = (a_b >= 0) ? 0 : Math.sqrt( -a_b );       return [ a * Math.sin( angRag ) - ea, b * Math.cos( angRag ) - eb, 0 ];   }      glArrayType = typeof Float32Array !="undefined" ? Float32Array : ( typeof WebGLFloatArray != "undefined" ? WebGLFloatArray : Array );      function IdentityMat44() {     var m = new glArrayType(16);     m[0]  = 1; m[1]  = 0; m[2]  = 0; m[3]  = 0;     m[4]  = 0; m[5]  = 1; m[6]  = 0; m[7]  = 0;     m[8]  = 0; m[9]  = 0; m[10] = 1; m[11] = 0;     m[12] = 0; m[13] = 0; m[14] = 0; m[15] = 1;     return m;   };      function RotateAxis(matA, angRad, axis) {       var aMap = [ [1, 2], [2, 0], [0, 1] ];       var a0 = aMap[axis][0], a1 = aMap[axis][1];        var sinAng = Math.sin(angRad), cosAng = Math.cos(angRad);       var matB = new glArrayType(16);       for ( var i = 0; i < 16; ++ i ) matB[i] = matA[i];       for ( var i = 0; i < 3; ++ i ) {           matB[a0*4+i] = matA[a0*4+i] * cosAng + matA[a1*4+i] * sinAng;           matB[a1*4+i] = matA[a0*4+i] * -sinAng + matA[a1*4+i] * cosAng;       }       return matB;   }      function Cross( a, b ) { return [ a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0], 0.0 ]; }   function Dot( a, b ) { return a[0]*b[0] + a[1]*b[1] + a[2]*b[2]; }   function Normalize( v ) {       var len = Math.sqrt( v[0] * v[0] + v[1] * v[1] + v[2] * v[2] );       return [ v[0] / len, v[1] / len, v[2] / len ];   }      var Camera = {};   Camera.create = function() {       this.pos    = [0, 3, 0.0];       this.target = [0, 0, 0];       this.up     = [0, 0, 1];       this.fov_y  = 90;       this.vp     = [800, 600];       this.near   = 0.5;       this.far    = 100.0;   }   Camera.Perspective = function() {       var fn = this.far + this.near;       var f_n = this.far - this.near;       var r = this.vp[0] / this.vp[1];       var t = 1 / Math.tan( Math.PI * this.fov_y / 360 );       var m = IdentityMat44();       m[0]  = t/r; m[1]  = 0; m[2]  =  0;                              m[3]  = 0;       m[4]  = 0;   m[5]  = t; m[6]  =  0;                              m[7]  = 0;       m[8]  = 0;   m[9]  = 0; m[10] = -fn / f_n;                       m[11] = -1;       m[12] = 0;   m[13] = 0; m[14] = -2 * this.far * this.near / f_n; m[15] =  0;       return m;   }   Camera.LookAt = function() {       var mz = Normalize( [ this.pos[0]-this.target[0], this.pos[1]-this.target[1], this.pos[2]-this.target[2] ] );       var mx = Normalize( Cross( this.up, mz ) );       var my = Normalize( Cross( mz, mx ) );       var tx = Dot( mx, this.pos );       var ty = Dot( my, this.pos );       var tz = Dot( [-mz[0], -mz[1], -mz[2]], this.pos );        var m = IdentityMat44();       m[0]  = mx[0]; m[1]  = my[0]; m[2]  = mz[0]; m[3]  = 0;       m[4]  = mx[1]; m[5]  = my[1]; m[6]  = mz[1]; m[7]  = 0;       m[8]  = mx[2]; m[9]  = my[2]; m[10] = mz[2]; m[11] = 0;       m[12] = tx;    m[13] = ty;    m[14] = tz;    m[15] = 1;        return m;   }       var ShaderProgram = {};   ShaderProgram.Create = function( shaderList ) {       var shaderObjs = [];       for ( var i_sh = 0; i_sh < shaderList.length; ++ i_sh ) {           var shderObj = this.CompileShader( shaderList[i_sh].source, shaderList[i_sh].stage );           if ( shderObj == 0 )               return 0;           shaderObjs.push( shderObj );       }       var progObj = this.LinkProgram( shaderObjs )       if ( progObj != 0 ) {           progObj.attribIndex = {};           var noOfAttributes = gl.getProgramParameter( progObj, gl.ACTIVE_ATTRIBUTES );           for ( var i_n = 0; i_n < noOfAttributes; ++ i_n ) {               var name = gl.getActiveAttrib( progObj, i_n ).name;               progObj.attribIndex[name] = gl.getAttribLocation( progObj, name );           }           progObj.unifomLocation = {};           var noOfUniforms = gl.getProgramParameter( progObj, gl.ACTIVE_UNIFORMS );           for ( var i_n = 0; i_n < noOfUniforms; ++ i_n ) {               var name = gl.getActiveUniform( progObj, i_n ).name;               progObj.unifomLocation[name] = gl.getUniformLocation( progObj, name );           }       }       return progObj;   }   ShaderProgram.AttributeIndex = function( progObj, name ) { return progObj.attribIndex[name]; }    ShaderProgram.UniformLocation = function( progObj, name ) { return progObj.unifomLocation[name]; }    ShaderProgram.Use = function( progObj ) { gl.useProgram( progObj ); }    ShaderProgram.SetUniformI1  = function( progObj, name, val ) { if(progObj.unifomLocation[name]) gl.uniform1i( progObj.unifomLocation[name], val ); }   ShaderProgram.SetUniformF1  = function( progObj, name, val ) { if(progObj.unifomLocation[name]) gl.uniform1f( progObj.unifomLocation[name], val ); }   ShaderProgram.SetUniformF2  = function( progObj, name, arr ) { if(progObj.unifomLocation[name]) gl.uniform2fv( progObj.unifomLocation[name], arr ); }   ShaderProgram.SetUniformF3  = function( progObj, name, arr ) { if(progObj.unifomLocation[name]) gl.uniform3fv( progObj.unifomLocation[name], arr ); }   ShaderProgram.SetUniformF4  = function( progObj, name, arr ) { if(progObj.unifomLocation[name]) gl.uniform4fv( progObj.unifomLocation[name], arr ); }   ShaderProgram.SetUniformM33 = function( progObj, name, mat ) { if(progObj.unifomLocation[name]) gl.uniformMatrix3fv( progObj.unifomLocation[name], false, mat ); }   ShaderProgram.SetUniformM44 = function( progObj, name, mat ) { if(progObj.unifomLocation[name]) gl.uniformMatrix4fv( progObj.unifomLocation[name], false, mat ); }   ShaderProgram.CompileShader = function( source, shaderStage ) {       var shaderScript = document.getElementById(source);       if (shaderScript)         source = shaderScript.text;       var shaderObj = gl.createShader( shaderStage );       gl.shaderSource( shaderObj, source );       gl.compileShader( shaderObj );       var status = gl.getShaderParameter( shaderObj, gl.COMPILE_STATUS );       if ( !status ) alert(gl.getShaderInfoLog(shaderObj));       return status ? shaderObj : null;   }    ShaderProgram.LinkProgram = function( shaderObjs ) {       var prog = gl.createProgram();       for ( var i_sh = 0; i_sh < shaderObjs.length; ++ i_sh )           gl.attachShader( prog, shaderObjs[i_sh] );       gl.linkProgram( prog );       status = gl.getProgramParameter( prog, gl.LINK_STATUS );       if ( !status ) alert("Could not initialise shaders");       gl.useProgram( null );       return status ? prog : null;   }      var VertexBuffer = {};   VertexBuffer.Create = function( attributes, indices ) {       var buffer = {};       buffer.buf = [];       buffer.attr = []       for ( var i = 0; i < attributes.length; ++ i ) {           buffer.buf.push( gl.createBuffer() );           buffer.attr.push( { size : attributes[i].attrSize, loc : attributes[i].attrLoc } );           gl.bindBuffer( gl.ARRAY_BUFFER, buffer.buf[i] );           gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( attributes[i].data ), gl.STATIC_DRAW );       }       buffer.inx = gl.createBuffer();       gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, buffer.inx );       gl.bufferData( gl.ELEMENT_ARRAY_BUFFER, new Uint16Array( indices ), gl.STATIC_DRAW );       buffer.inxLen = indices.length;       gl.bindBuffer( gl.ARRAY_BUFFER, null );       gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, null );       return buffer;   }   VertexBuffer.Draw = function( bufObj ) {     for ( var i = 0; i < bufObj.buf.length; ++ i ) {           gl.bindBuffer( gl.ARRAY_BUFFER, bufObj.buf[i] );           gl.vertexAttribPointer( bufObj.attr[i].loc, bufObj.attr[i].size, gl.FLOAT, false, 0, 0 );           gl.enableVertexAttribArray( bufObj.attr[i].loc );       }       gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufObj.inx );       gl.drawElements( gl.TRIANGLES, bufObj.inxLen, gl.UNSIGNED_SHORT, 0 );       for ( var i = 0; i < bufObj.buf.length; ++ i )          gl.disableVertexAttribArray( bufObj.attr[i].loc );       gl.bindBuffer( gl.ARRAY_BUFFER, null );       gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, null );   }      initScene();    })();

html,body {     height: 100%;     width: 100%;     margin: 0;     overflow: hidden; }  #gui {     position : absolute;     top : 0;     left : 0; }

<script id="draw-shader-vs" type="x-shader/x-vertex">     precision highp float;          attribute vec3 inPos;     attribute vec3 inNV;     attribute vec3 inCol;        varying vec3 vertPos;     varying vec3 vertNV;     varying vec3 vertCol;          uniform mat4 u_projectionMat44;     uniform mat4 u_viewMat44;     uniform mat4 u_modelMat44;          void main()     {            mat4 mv       = u_viewMat44 * u_modelMat44;          vertCol       = inCol;         vertNV        = normalize(mat3(mv) * inNV);         vec4 viewPos  = mv * vec4( inPos, 1.0 );         vertPos       = viewPos.xyz;         gl_Position   = u_projectionMat44 * viewPos;     } </script>    <script id="draw-shader-fs" type="x-shader/x-fragment">     precision mediump float;      varying vec3 vertPos;     varying vec3 vertNV;     varying vec3 vertCol;          uniform float u_shininess;     uniform float u_glow;          void main()     {         vec3 color = vertCol;         vec3  normalV  = normalize( vertNV );         vec3  eyeV     = normalize( -vertPos );         vec3  halfV    = normalize( eyeV + normalV );         float NdotH    = max( 0.0, dot( normalV, halfV ) );         float shineFac = ( u_shininess + 2.0 ) * pow( NdotH, u_shininess ) / ( 2.0 * 3.14159265 );         gl_FragColor   = vec4( u_glow*0.1 + color.rgb * u_glow * shineFac * 0.5, 1.0 );     }  </script>    <script id="post-shader-vs" type="x-shader/x-vertex">     precision mediump float;          attribute vec2 inPos;          varying   vec2 pos;          void main()     {         pos = inPos;         gl_Position = vec4( inPos, 0.0, 1.0 );     } </script>      <script id="blurX-shader-fs" type="x-shader/x-fragment">     precision mediump float;          varying vec2 pos;          uniform sampler2D u_texture;     uniform vec2      u_textureSize;     uniform float     u_sigma;          float CalcGauss( float x, float sigma )     {       float coeff = 1.0 / (2.0 * 3.14157 * sigma);       float expon = -(x*x) / (2.0 * sigma);       return (coeff*exp(expon));     }          void main()     {         vec2 texC = pos.st * 0.5 + 0.5;         vec4 texCol = texture2D( u_texture, texC );         vec4 gaussCol = vec4( texCol.rgb, 1.0 );         float stepX = 1.0 / u_textureSize.x;         for ( int i = 1; i <= 20; ++ i )         {             float weight = CalcGauss( float(i) / 32.0, u_sigma * 0.5 );             texCol = texture2D( u_texture, texC + vec2( float(i) * stepX, 0.0 ) );             gaussCol += vec4( texCol.rgb * weight, weight );             texCol = texture2D( u_texture, texC - vec2( float(i) * stepX, 0.0 ) );             gaussCol += vec4( texCol.rgb * weight, weight );         }         gaussCol.rgb /= gaussCol.w;         gl_FragColor = vec4( gaussCol.rgb, 1.0 );     } </script>      <script id="blurY-shader-fs" type="x-shader/x-fragment">     precision mediump float;          varying vec2 pos;          uniform sampler2D u_texture;     uniform vec2      u_textureSize;     uniform float     u_sigma;          float CalcGauss( float x, float sigma )     {       float coeff = 1.0 / (2.0 * 3.14157 * sigma);       float expon = -(x*x) / (2.0 * sigma);       return (coeff*exp(expon));     }          void main()     {         vec2 texC = pos.st * 0.5 + 0.5;         vec4 texCol = texture2D( u_texture, texC );         vec4 gaussCol = vec4( texCol.rgb, 1.0 );         float stepY = 1.0 / u_textureSize.y;         for ( int i = 1; i <= 20; ++ i )         {             float weight = CalcGauss( float(i) / 32.0, u_sigma * 0.5 );             texCol = texture2D( u_texture, texC + vec2( 0.0, float(i) * stepY ) );             gaussCol += vec4( texCol.rgb * weight, weight );             texCol = texture2D( u_texture, texC - vec2( 0.0, float(i) * stepY ) );             gaussCol += vec4( texCol.rgb * weight, weight );         }         vec3 hdrCol = 2.0 * gaussCol.xyz / gaussCol.w;         vec3 mappedCol = vec3( 1.0 ) - exp( -hdrCol.rgb * 3.0 );         gl_FragColor = vec4( clamp( mappedCol.rgb, 0.0, 1.0 ), 1.0 );     } </script>  <div>     <form id="gui" name="inputs">         <table>             <tr> <td> <font color= #CCF>shininess</font> </td>                   <td> <input type="range" id="shine" min="0" max="50" value="10" onchange="changeEventHandler(event);"/></td> </tr>             <tr> <td> <font color= #CCF>glow</font> </td>                   <td> <input type="range" id="glow" min="100" max="400" value="250" onchange="changeEventHandler(event);"/></td> </tr>             <tr> <td> <font color= #CCF>blur</font> </td>                   <td> <input type="range" id="sigma" min="1" max="100" value="60" onchange="changeEventHandler(event);"/></td> </tr>         </table>     </form> </div>  <canvas id="canvas" style="border: none;" width="100%" height="100%"></canvas>