Comment obtenir un effet" Glow " dans OpenGLES 2.0?

tout d'abord, il y a des tonnes d'algorithmes et de techniques pour générer un effet de lueur. Je veux juste présenter une possibilité.

d'Abord, vous devez créer un Matériau qui est auto-lumineux. Pour cela j'utilise un modèle de lumière modifié blinn-phong, dans lequel la direction de la source lumineuse est toujours la direction inverse du vecteur normal du 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 );

    fragColor = vec4( u_glow * (0.1 + color.rgb * glowFac * 0.5), 1.0 );
}

dans une deuxième étape un algorithme gaussien flou est effectué sur le sortie. La scène est écrite pour encadrer le tampon avec une texture liée au plan de couleur. Une passe d'espace d'écran utilise la texture comme entrée pour brouiller la sortie.

Pour des raisons de performance, l'algorithme de flou est d'abord exécuté le long de l'axe X du viewport et dans une autre étape le long de l'axe Y du viewport.

Une description détaillée de l'algorithme de flou peut être trouvée à la réponse à la question OpenGL es 2.0 Gaussian flou sur triangle .

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 );
}

Voir aussi les réponses à la question suivante:

• OpenGL es 2.0, flou Gaussien sur le triangle
• quel type de flou peut être mis en œuvre dans les pixels shaders?

voir l'exemple WebGL similaire suivant qui réunit tous les éléments:

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>

Le site web GLSL bac à sable a une collection de shader exemples. celui-ci a la lueur et semble pouvoir compiler pour ES .

vous devriez pouvoir les Modifier pour tirer les uv de votre texture.

Voici un code provenant directement de ce site:

#ifdef GL_ES
precision mediump float;
#endif

#extension GL_OES_standard_derivatives : enable

uniform float time;
uniform vec2 mouse;
uniform vec2 resolution;

void main(void){

    vec2 p = (gl_FragCoord.xy * 2.0 - resolution) / min(resolution.x, resolution.y);
    vec3 color1 = vec3(0.0, 0.3, 0.5);
    vec3 color2 = vec3(0.5, 0.0, 0.3);

    float f = 0.0;
    float g = 0.0;
    float h = 0.0;
    float PI = 3.14159265;
    for(float i = 0.0; i < 40.0; i++){
        if (floor(mouse.x * 41.0) < i)
            break;
        float s = sin(time + i * PI / 20.0) * 0.8;
        float c = cos(time + i * PI / 20.0) * 0.8;
        float d = abs(p.x + c);
        float e = abs(p.y + s);
        f += 0.001 / d;
        g += 0.001 / e;
        h += 0.00003 / (d * e);
    }


    gl_FragColor = vec4(f * color1 + g * color2 + vec3(h), 1.0);
}