Function updatePositionProgram

src/lib/programs/updatePositionProgram.js:12–199

(ctx)

const particlePositionShaderCodeBuilder = new UpdatePositionGraph();

export default function updatePositionProgram(ctx) {
  var gl = ctx.gl;
  var readTextures, writeTextures;
  var particleStateResolution;
  var updateProgram;
  var readVelocity = makeReadProgram(ctx);

  // If someone needs to get vectors out from the GPU, they send a `vector-lines-request`
  // over the bus. This request is delayed until next compute frame. Once it is handled,
  // we send them back response with calculated vectors.
  var pendingVectorLines;

  // TODO: need to make sure we are not leaking.
  bus.on('vector-lines-request', putVectorLinesRequestIntoQueue);

  return {
    updateCode,
    updateParticlesPositions,
    updateParticlesCount,
    prepareToDraw,
  };

  function updateCode(vectorField) {
    particlePositionShaderCodeBuilder.setCustomVectorField(vectorField);
    let fragment = particlePositionShaderCodeBuilder.getFragmentShader();
    let vertex = particlePositionShaderCodeBuilder.getVertexShader();

    let newProgram = util.createProgram(gl, vertex, fragment);

    if (updateProgram) updateProgram.unload();
    updateProgram = newProgram;

    if (ctx.colorMode === ColorMode.VELOCITY) readVelocity.requestSpeedUpdate();
  }
  
  function updateParticlesCount(x, y) {
    particleStateResolution = ctx.particleStateResolution;

    var dimensions = [{
      name: 'x',
      particleState: x
    }, {
      name: 'y',
      particleState: y
    }];

    if (readTextures) readTextures.dispose();
    readTextures = textureCollection(gl, dimensions, particleStateResolution);

    if (writeTextures) writeTextures.dispose();
    writeTextures = textureCollection(gl, dimensions, particleStateResolution);

    readVelocity.updateParticlesCount();
  }

  function prepareToDraw(program) {
    var colorMode = ctx.colorMode;
    if (colorMode === ColorMode.VELOCITY) readVelocity.setColorMinMax(program);