Add brightness and contrast controls, thanks @evanw

src/ol/webgl/layerrenderer.js

@@ -56,6 +56,22 @@ ol.webgl.LayerRenderer.prototype.getMap = function() {
 ol.webgl.LayerRenderer.prototype.getMatrix = goog.abstractMethod;
 
 
+/**
+ * @inheritDoc
+ */
+ol.webgl.LayerRenderer.prototype.handleLayerBrightnessChange = function() {
+  this.dispatchChangeEvent();
+};
+
+
+/**
+ * @inheritDoc
+ */
+ol.webgl.LayerRenderer.prototype.handleLayerContrastChange = function() {
+  this.dispatchChangeEvent();
+};
+
+
 /**
  * @inheritDoc
  */

src/ol/webgl/map.js

@@ -34,6 +34,7 @@ ol.DEBUG_WEBGL = false;
 /**
  * @constructor
  * @extends {ol.webgl.shader.Fragment}
+ * @see https://github.com/evanw/glfx.js/blob/master/src/filters/adjust/brightnesscontrast.js
  * @see https://github.com/evanw/glfx.js/blob/master/src/filters/adjust/huesaturation.js
  */
 ol.webgl.map.shader.Fragment = function() {
@@ -41,6 +42,8 @@ ol.webgl.map.shader.Fragment = function() {
     'precision mediump float;',
     '',
     'uniform mat4 uMatrix;',
+    'uniform float uBrightness;',
+    'uniform float uContrast;',
     'uniform float uHue;',
     'uniform float uOpacity;',
     'uniform float uSaturation;',
@@ -71,6 +74,13 @@ ol.webgl.map.shader.Fragment = function() {
     '    color.rgb += (average - color.rgb) * (-uSaturation);',
     '  }',
     '',
+    '  color.rgb += uBrightness;',
+    '  if (uContrast > 0.0) {',
+    '    color.rgb = (color.rgb - 0.5) / (1.0 - uContrast) + 0.5;',
+    '  } else {',
+    '    color.rgb = (color.rgb - 0.5) * (1.0 + uContrast) + 0.5;',
+    '  }',
+    '',
     '  color.a = color.a * uOpacity;',
     '',
     '  gl_FragColor = color;',
@@ -156,6 +166,8 @@ ol.webgl.Map = function(target, opt_values) {
    * @private
    * @type {{aPosition: number,
    *         aTexCoord: number,
+   *         uBrightness: WebGLUniformLocation,
+   *         uContrast: WebGLUniformLocation,
    *         uHue: WebGLUniformLocation,
    *         uMatrix: WebGLUniformLocation,
    *         uOpacity: WebGLUniformLocation,
@@ -484,6 +496,8 @@ ol.webgl.Map.prototype.renderInternal = function() {
     this.locations_ = {
       aPosition: gl.getAttribLocation(program, 'aPosition'),
       aTexCoord: gl.getAttribLocation(program, 'aTexCoord'),
+      uBrightness: gl.getUniformLocation(program, 'uBrightness'),
+      uContrast: gl.getUniformLocation(program, 'uContrast'),
       uHue: gl.getUniformLocation(program, 'uHue'),
       uMatrix: gl.getUniformLocation(program, 'uMatrix'),
       uOpacity: gl.getUniformLocation(program, 'uOpacity'),
@@ -517,6 +531,8 @@ ol.webgl.Map.prototype.renderInternal = function() {
   this.forEachVisibleLayer(function(layer, layerRenderer) {
     gl.uniformMatrix4fv(
         this.locations_.uMatrix, false, layerRenderer.getMatrix());
+    gl.uniform1f(this.locations_.uBrightness, layer.getBrightness());
+    gl.uniform1f(this.locations_.uContrast, layer.getContrast());
     gl.uniform1f(this.locations_.uHue, layer.getHue());
     gl.uniform1f(this.locations_.uOpacity, layer.getOpacity());
     gl.uniform1f(this.locations_.uSaturation, layer.getSaturation());