Using RenderTexture Painting Shader

Leave persistent damage from laser or other weapons on the environment

Setup:

This is the basic setup from linked code, Raycast to the mouse position when you click, adding the brush texture to the lightmap based RenderTexture result on collision 

Trails

Let the player leave trails with depth in snow/ sand

Setup:

Set up your shader for tesselation, the Unity Manual here shows how to 

Add a vertex function for displacement, using the Paintmap as a texture reference for pushing the vertices

void disp(inout appdata v)
{
float d = tex2Dlod(_PaintMap, float4(v.texcoord1.xy, 0, 0)).r * _Height;
v.vertex.xyz += v.normal *d;
}

Now the untouched parts of the snow/sand are slightly higher, and the paintbrush script will push it down

Map Notes

Letting the Player add notes or draw on a map

Setup:

You dont need the shader for this
Set up a canvas with a raw image, and make a RenderTexture for it

Instead of Raycasting, use the mouse position to paint to the RenderTexture. Get the X and Y coordinates by 

xCoordinate = Mathf.Floor(Input.mousePosition.x – rawImage.rectTransform.position.x);

yCoordinate = Mathf.Floor(Input.mousePosition.y – rawImage.rectTransform.position.y);

DrawTexture(texture, xCoordinate, yCoordinate);

With this you can draw on the RawImage UI component

Player Made Textures

Use the painted RenderTextures as a Texture2D for models

Setup:

Start the same way as the draw map example

To convert the rendertexture to a usable texture, Make a new Texture2D and read the active RenderTexture’s pixels

 Texture2D toTexture2D(RenderTexture rTex)

{
sourceTex = new Texture2D(rTex.width, rTex.height, TextureFormat.RGB24, false);
RenderTexture.active = rTex;
sourceTex.ReadPixels(new Rect(0, 0, rTex.width, rTex.height), 0, 0);
sourceTex.Apply();
RenderTexture.active = null;
return sourceTex;
}

Then assign the result texture to your renderer, and you’ve got a user made custom material!

Joyce (MinionsArt) 

Make sure to follow Joyce on Twitter and support the artist on Patreon if you find his work useful.