VertexDisplacement.md

Vertex displacement

All magic in a vertex displacement shader takes place in the vertex shader(obviously). Most include manipulation of the vertex position put sometimes it also includes its normal and UV cordinates.

Displace over time based on world position

void vert(inout appdata_full v) {
	half3  position = v.vertex.xyz;
	half3 offset = mul(unity_WorldToObject, sin(_Time.w));
	position.xz += (offset.xz * localStrength);	// Only move vertex along the XZ plane
	v.vertex.xyz = position;
}

Displacement based on model space

Displaces vertex in its (local) YZ plane base on its distance from origo in model space.

void vert(inout appdata_full v){
	float3 position = v.vertex.xyz;
	float amplitude = 0.001 * _Amplitude * abs(position.y);
	float waves = 2 * UNITY_PI / _WaveLength;

	float ofset = waves * (position.y + _Time.w * _Speed);
	float3 tangent = normalize(float3(1, waves * amplitude * cos(ofset), 0));
	float3 normal = float3(-tangent.y, tangent.x, 0);

	position.z = (sin(ofset) - 0.75) * amplitude ;

	v.vertex.xyz = position;
	v.normal = normal;
}

Displace based on normals

Displaces the vertex "forward" based on their normal direction.

(This shader also uses a grab pass display the underlying render buffer displaced and heavy alpha in the middle (with a Rim effect) to display the underlying render buffer unaltered).

half4 pos = UnityObjectToClipPos(v.vertex);
o._uvGrabTex = ComputeGrabScreenPos(pos);
float3 worldPos = mul (unity_ObjectToWorld, v.vertex).xyz;
v.vertex.xyz += v.normal * sin((_Time * 5) + worldPos.xyz) * 0.1;