webgl - Using sample2D as position in vertex shader -

i'm learning how manipulate particles fbo in webgl, tried store position texture , use position reference, nothing came on stage.

fragment shaders

precision mediump float;  void main() {  gl_fragcolor = vec4(vec3(1.0), 1.0);  }  </script> 

vertex render shader script

attribute vec2 atextureuv; uniform sampler2d utexture;  void main() { vec4 texture = texture2d( utexture, atextureuv ); gl_position = vec4( texture.rgb, 1.0 ); gl_pointsize = 3; }  </script> 

js script

// determine uvs var uvs = new float32array([ 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 1.0, 1.0 ])  var uvbuffer = gl.createbuffer(); gl.bindbuffer( gl.array_buffer, uvbuffer ); gl.bufferdata( gl.array_buffer, uvs, gl.static_draw ); gl.enablevertexattribarray( defaultprogram.atextureuvloc ); gl.vertexattribpointer( defaultprogram.atextureuvloc, 2, gl.float, false, 0, 0);  // texture initialization for(var = 0; < particlecount; i++) {             initialdata.push(                 math.random(),                 math.random(),                 math.random(),                 0             );         }  var texture = gl.createtexture(); gl.activetexture( gl.texture0 ); gl.bindtexture( gl.texture_2d, texture ); gl.pixelstorei( gl.unpack_alignment, 1 );  gl.teximage2d( gl.texture_2d, 0, gl.rgba, fbowidth, fbowidth, 0, gl.rgba, gl.float, new float32array(initialdata) );  gl.texparameteri(gl.texture_2d, gl.texture_min_filter, gl.nearest); gl.texparameteri(gl.texture_2d, gl.texture_mag_filter, gl.nearest);  .....   function draw() {     requestanimationframe( draw );     gl.viewport( 0, 0, gl.drawingbufferwidth, gl.drawingbufferheight );    gl.clear( gl.color_buffer_bit | gl.depth_buffer_bit);    gl.drawarrays( gl.points, 0, particlecount ); } 

can't comment yet, desktop gl remark, can see 1) there no actual draw calls in script i.e. gldrawelements/gldrawarrays (unless you've left parts of out), , 2) you're missing fragment shader. refer e.g. this.