flow like the river

VISUALIZACION/node_modules/three/examples/jsm/shaders/HueSaturationShader.js

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+/**
+ * Hue and saturation adjustment
+ * https://github.com/evanw/glfx.js
+ * hue: -1 to 1 (-1 is 180 degrees in the negative direction, 0 is no change, etc.
+ * saturation: -1 to 1 (-1 is solid gray, 0 is no change, and 1 is maximum contrast)
+ */
+
+const HueSaturationShader = {
+
+	name: 'HueSaturationShader',
+
+	uniforms: {
+
+		'tDiffuse': { value: null },
+		'hue': { value: 0 },
+		'saturation': { value: 0 }
+
+	},
+
+	vertexShader: /* glsl */`
+
+		varying vec2 vUv;
+
+		void main() {
+
+			vUv = uv;
+
+			gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
+
+		}`,
+
+	fragmentShader: /* glsl */`
+
+		uniform sampler2D tDiffuse;
+		uniform float hue;
+		uniform float saturation;
+
+		varying vec2 vUv;
+
+		void main() {
+
+			gl_FragColor = texture2D( tDiffuse, vUv );
+
+			// hue
+			float angle = hue * 3.14159265;
+			float s = sin(angle), c = cos(angle);
+			vec3 weights = (vec3(2.0 * c, -sqrt(3.0) * s - c, sqrt(3.0) * s - c) + 1.0) / 3.0;
+			float len = length(gl_FragColor.rgb);
+			gl_FragColor.rgb = vec3(
+				dot(gl_FragColor.rgb, weights.xyz),
+				dot(gl_FragColor.rgb, weights.zxy),
+				dot(gl_FragColor.rgb, weights.yzx)
+			);
+
+			// saturation
+			float average = (gl_FragColor.r + gl_FragColor.g + gl_FragColor.b) / 3.0;
+			if (saturation > 0.0) {
+				gl_FragColor.rgb += (average - gl_FragColor.rgb) * (1.0 - 1.0 / (1.001 - saturation));
+			} else {
+				gl_FragColor.rgb += (average - gl_FragColor.rgb) * (-saturation);
+			}
+
+		}`
+
+};
+
+export { HueSaturationShader };