shader: function()

in effects/seriously.hue-saturation.js [24:94]

• 52 lines of code
• 1 McCabe index (conditional complexity)

		shader: function (inputs, shaderSource) {
			shaderSource.vertex = [
				'precision mediump float;',

				'attribute vec4 position;',
				'attribute vec2 texCoord;',

				'uniform vec2 resolution;',
				'uniform mat4 projection;',
				'uniform mat4 transform;',

				'uniform float hue;',
				'uniform float saturation;',

				'varying vec2 vTexCoord;',

				'varying vec3 weights;',

				'void main(void) {',
				'	float angle = hue * 3.14159265358979323846264;',
				'	float s = sin(angle);',
				'	float c = cos(angle);',
				'	weights = (vec3(2.0 * c, -sqrt(3.0) * s - c, sqrt(3.0) * s - c) + 1.0) / 3.0;',

				// first convert to screen space
				'	vec4 screenPosition = vec4(position.xy * resolution / 2.0, position.z, position.w);',
				'	screenPosition = transform * screenPosition;',

				// convert back to OpenGL coords
				'	gl_Position = screenPosition;',
				'	gl_Position.xy = screenPosition.xy * 2.0 / resolution;',
				'	gl_Position.z = screenPosition.z * 2.0 / (resolution.x / resolution.y);',
				'	vTexCoord = texCoord;',
				'}'
			].join('\n');
			shaderSource.fragment = [
				'precision mediump float;',

				'varying vec2 vTexCoord;',

				'varying vec3 weights;',

				'uniform sampler2D source;',
				'uniform float hue;',
				'uniform float saturation;',

				'void main(void) {',
				'	vec4 color = texture2D(source, vTexCoord);',

				//adjust hue
				'	float len = length(color.rgb);',
				'	color.rgb = vec3(' +
						'dot(color.rgb, weights.xyz), ' +
						'dot(color.rgb, weights.zxy), ' +
						'dot(color.rgb, weights.yzx) ' +
				');',

				//adjust saturation
				'	vec3 adjustment = (color.r + color.g + color.b) / 3.0 - color.rgb;',
				'	if (saturation > 0.0) {',
				'		adjustment *= (1.0 - 1.0 / (1.0 - saturation));',
				'	} else {',
				'		adjustment *= (-saturation);',
				'	}',
				'	color.rgb += adjustment;',

				'	gl_FragColor = color;',
				'}'
			].join('\n');
			return shaderSource;
		},