Animated Noise Cloud Shader

This algorithm utilized a 3D Perlin noise function provided from the OpenGL Orange Book. This noise function created a 3D noise texture which can be passed into the GLSL shader. The shader than uses the current execution time of the OpenGL program as an offset for the texture lookup. As a result this creates a very smooth animation as clouds appear to drift, shrink, grow, or even disappear. While this algorithm was very simple it's result created a very visually appealing cloud animation.

Animated noise based cloud shader.

	/**
	* GLSL fragment shader for the noise clouds.
	*
	* @author Ian Stewart
	*
	*/
	varying float LightIntensity;
	varying vec3 MCposition;
	uniform sampler3D Noise;
	uniform vec3 SkyColor;
	uniform vec3 CloudColor;
	uniform int TIME_FROM_INIT;
	vec3 Offset = vec3(0.0,0.0,0.0);
	void main()
	{
	float offset = float(TIME_FROM_INIT) *0.00005;
	Offset = vec3(-offset, offset, offset);
	vec4 noisevec = texture3D(Noise, MCposition+Offset);
	float intensity = (noisevec[0] + noisevec[1] + noisevec[2]
	+ noisevec[3] + 0.03125) * 1.0;
	vec3 color = mix(SkyColor, CloudColor, intensity) * LightIntensity;
	color = clamp(color, 0.0, 1.0);
	gl_FragData[0] = vec4(color, 1.0);
	}

view raw perlin.frag hosted with ❤ by GitHub

	/**
	* GLSL vertex shader for the noise clouds.
	*
	* @author Ian Stewart
	*
	*/
	varying float LightIntensity;
	varying vec3 MCposition;
	uniform vec3 LightPos;
	uniform float Scale;
	void main()
	{
	gl_Position = ftransform();
	vec3 ECposition = vec3(gl_ModelViewMatrix * gl_Vertex);
	MCposition = vec3(gl_Vertex) * Scale;
	vec3 tnorm = -normalize(vec3(gl_NormalMatrix * gl_Normal));
	LightIntensity = dot(normalize(LightPos - ECposition), tnorm) * 1.5;
	//LightIntensity = 1.5;
	}

view raw perlin.vert hosted with ❤ by GitHub