WebGLShaderPrecisionFormat : Object

WebGLShaderPrecisionFormat describes the precision of a WebGLShader. WebGLShaderPrecisionFormats are returned from getShaderPrecisionFormat().

Spec

Instance Properties

precision : Number readonly

The number of bits of precision for the specified type. INT types always return 0.

Example:

<canvas id='canvas'></canvas>
<script>
  var canvas = document.getElementById('canvas');
  var gl = canvas.getContext('webgl') || canvas.getContext('experimental-webgl');

  var precisionTypes = ['LOW_FLOAT', 'MEDIUM_FLOAT', 'HIGH_FLOAT',
                        'LOW_INT',   'MEDIUM_INT',   'HIGH_INT'];
  var targetTypes = ['FRAGMENT_SHADER', 'VERTEX_SHADER'];

  precisionTypes.forEach(function(precisionType) {
    targetTypes.forEach(function(targetType) {
      var format = gl.getShaderPrecisionFormat(gl[targetType], gl[precisionType]);
      console.log(targetType + ', ' + precisionType);
      console.log('    precision: ' + format.precision +
                  ', rangeMin: ' + format.rangeMin +
                  ', rangeMax: ' + format.rangeMax);
    });
  });
</script>

Run

Results:

rangeMax : Number readonly

The log base 2 of the maximum value that can be represented by the specified type. For example, if rangeMax is 31, the maximum value that can be represented is Math.pow(2, 31).

Example:

<canvas id='canvas'></canvas>
<script>
  var canvas = document.getElementById('canvas');
  var gl = canvas.getContext('webgl') || canvas.getContext('experimental-webgl');

  var precisionTypes = ['LOW_FLOAT', 'MEDIUM_FLOAT', 'HIGH_FLOAT',
                        'LOW_INT',   'MEDIUM_INT',   'HIGH_INT'];
  var targetTypes = ['FRAGMENT_SHADER', 'VERTEX_SHADER'];

  precisionTypes.forEach(function(precisionType) {
    targetTypes.forEach(function(targetType) {
      var format = gl.getShaderPrecisionFormat(gl[targetType], gl[precisionType]);
      console.log(targetType + ', ' + precisionType);
      console.log('    precision: ' + format.precision +
                  ', rangeMin: ' + format.rangeMin +
                  ', rangeMax: ' + format.rangeMax);
    });
  });
</script>

Run

Results:

rangeMin : Number readonly

The log base 2 of the absolute value of the minimum (ie, most negative) value that can be represented by the specified type. For example, if rangeMin is 31, the minimum value that can be represented is -Math.pow(2, 31).

Example:

<canvas id='canvas'></canvas>
<script>
  var canvas = document.getElementById('canvas');
  var gl = canvas.getContext('webgl') || canvas.getContext('experimental-webgl');

  var precisionTypes = ['LOW_FLOAT', 'MEDIUM_FLOAT', 'HIGH_FLOAT',
                        'LOW_INT',   'MEDIUM_INT',   'HIGH_INT'];
  var targetTypes = ['FRAGMENT_SHADER', 'VERTEX_SHADER'];

  precisionTypes.forEach(function(precisionType) {
    targetTypes.forEach(function(targetType) {
      var format = gl.getShaderPrecisionFormat(gl[targetType], gl[precisionType]);
      console.log(targetType + ', ' + precisionType);
      console.log('    precision: ' + format.precision +
                  ', rangeMin: ' + format.rangeMin +
                  ', rangeMax: ' + format.rangeMax);
    });
  });
</script>

Run

Results:

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