How to encode and send float data to GLSL from Javascript/THREE.js and decode results -


i encode object positions (x,y,z) , send glsl shader, decode data, perform calculations , send results cpu. have researched issue , have found partial answers decode rgb value single float without bit-shift in glsl, have not been successful in encoding , decoding results.

here part of code.`...

function init() {    ...    buffer = gl.createbuffer();    gl.bindbuffer(gl.array_buffer, buffer);    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    );      texture = gl.createtexture();    gl.bindtexture(gl.texture_2d, texture);      vec1 = new three.vector3(2.6, 3.3, 100.80); //example position vector      data = new uint8array([float2color(vec1.x).r, float2color(vec1.x).g, float2color(vec1.x).b, 255, //x      float2color(vec1.y).r, float2color(vec1.y).g, float2color(vec1.y).b, 255, //y      float2color(vec1.z).r, float2color(vec1.z).g, float2color(vec1.z).b, 255 //z    ]);     // encodes give me int8array [ 2, 0, 0, 255, 3, 0, 0, 255, 100, 0, 2 more… ]        gl.teximage2d(gl.texture_2d, level, gl.rgba, width, height, 0, gl.rgba, gl.unsigned_byte, data);  }    //render function    function render() {    ...    gl.drawarrays(gl.points, 0, 2);    var pixels = new uint8array(width * height * 4);    gl.readpixels(0, 0, width, height, gl.rgba, gl.float, pixels);    pixels = new uint8array(pixels.buffer);        //after getting results glsl, pixels    //uint8array [ 255, 0, 0, 255, 255, 0, 0, 255, 255, 0, … ]           var color = {      r: pixels[0],      g: pixels[1],      b: pixels[2]    };    float1 = decodevec3tofloat(color); // decode , use data after position updated in glsl  }    function float2color( f ) {          b = math.floor(f / 255.0 / 255.0);          g = math.floor((f - (b * 255.0 * 255.0) ) / 255.0);          // r = math.floor(f - (b * 255.0 * 255.0) - (g * 255.0) );          r = math.floor(f % 255);          return {r:r, g:g, b:b};      }    function decodevec3tofloat(color) {          var result;          result = color.r * 255.0;          result += color.g * 255.0 * 255.0;          result += color.b * 255.0 * 255.0 * 255.0;          return result;      }

i've been working sort of thing myself. can use datatextures achieve this, , pass them in , out buffers manipulated simulation shader. best example i've found far uses dated version of three.js (v58) can updated. found helpful scripts updated , toy around until understood enough use case. note in example there fixed values passed through in simulation shader, changing x,y,z values rendered in , out on buffers. luck!

update:

i have since discoverer old three.fboutils script using above has been updated , reworked , called three.gpucomputationrenderer -- works great! (v80)


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