Old Unity Examples

 
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shawnpigott



Joined: 28 Sep 2005
Posts: 213
Location: Vancouver Island Canada
PostPosted: Fri Oct 31, 2008 3:07 am    Post subject: Old Unity Examples Reply with quote
A while back there was an example project on the Unity website that showed how to paint directly onto objects. I think it may have used vertex colouring. In any event, I can't find it on the site and was wondering if anyone knew where to find a copy.

I'm hoping to modify it so that I can create the effects of scrubbing paint off of a wall. My idea is to have an alpha texture map that is slowly painted away to reveal an image map underneath. I'm not sure if I'm on the right track, but I thought that it would be a good place to start.
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StarManta



Joined: 23 Oct 2006
Posts: 1522
Location: Columbus, OH
PostPosted: Fri Oct 31, 2008 4:29 am    Post subject: Reply with quote
I don't know where the example is, but it used RaycastHit.textureCoords to modify the texture itself (not vertex coloring). I think the RaycastHit documentation has some info that should get you started.
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drJones



Joined: 19 Oct 2005
Posts: 1342
Location: New Hampshire
PostPosted: Fri Oct 31, 2008 1:02 pm    Post subject: Reply with quote
its in the *old* procedural package, haven't checked if it works with 2.1 but this should be the script:


Code:
/*
Allows you to paint on textures with arbitrary brushes.

* You have to use MeshColliders, otherwise the
* texture coordinates cant be determined.
* You have to map your textures uniquely (no repeating textures) and
* your textures may not use texture compression.
*/


// The decal texture we use to paint. Alpha of the texture can be used to fade in the decal.
var decalMap : Texture2D;
//
var opacity = 1.0;
// Tint's the color we paint into the texture
var tintColor = Color.white;

// Enable this when painting normal maps
var paintNormalMap = false;

var instantiateModifiedTextures = true;

private var instantiatedTextures = ArrayList ();

function ApplyDecal (uv : Vector2, target : Texture2D)
{
   var pixelX : int = uv.x * target.width;
   var pixelY : int = uv.y * target.height;

   var unmodifiedMinX : int = pixelX - decalMap.width / 2;
   var unmodifiedMinY : int = pixelY - decalMap.height / 2;
   
   var minx : int = Mathf.Clamp(pixelX - decalMap.width / 2, 0, target.width);
   var miny : int = Mathf.Clamp(pixelY - decalMap.height / 2, 0, target.width);

   var maxX : int = Mathf.Clamp(pixelX + decalMap.width / 2, 0, target.width);
   var maxY : int = Mathf.Clamp(pixelY + decalMap.height / 2, 0, target.height);

   // Painting into empty an empty area? Don't do that
   if (minx == maxX || miny == maxY)
   {
      target.Apply();
      return;
   }

   // Read the pixels from the target texture
   var srcPixels = target.GetPixels(minx, miny, maxX - minx, maxY - miny);
   
   // Read the pixels from the decal texture
   var decalPixels = decalMap.GetPixels(minx - unmodifiedMinX, miny - unmodifiedMinY, maxX - minx, maxY - miny);

   // Paint the pixels
   // We use the alpha of the decal to fade in the decal smoothly
   for (var i=0;i<srcPixels.Length;i++)
   {
      var blendFactor = decalPixels[i].a * opacity;
      var targetColor = tintColor * decalPixels[i];
      srcPixels[i] = Color.Lerp(srcPixels[i], targetColor, blendFactor);
   }
   
   // Apply the pixels
   target.SetPixels(minx, miny, maxX - minx, maxY - miny, srcPixels);
   target.Apply();
}

function GrabTexture (renderer : Renderer)
{
   // Get the bump map or diffuse texture
   var paintTex : Texture2D;
   if (paintNormalMap)
      paintTex = renderer.sharedMaterial.GetTexture("_BumpMap") as Texture2D;
   else
      paintTex = renderer.sharedMaterial.mainTexture as Texture2D;

   // Should we duplicate the texture before modifying it?   
   if (instantiateModifiedTextures)
   {
      if (instantiatedTextures.IndexOf(renderer) == -1)
      {
         var cloned : Texture2D;
         if (paintTex != null)
         {
            cloned = new Texture2D (paintTex.width, paintTex.height);
            cloned.SetPixels(paintTex.GetPixels());
            paintTex = cloned;
         }
         else
         {
            cloned = new Texture2D (256, 256);
            var colors = new Color[cloned.width * cloned.height];
            var clearColor = Color.white;
            if (paintNormalMap)
               clearColor = Color (0.5,0.5,1,1);
            
            for (var i=0;i<colors.length;i++)
               colors[i] = clearColor;

            cloned.SetPixels(colors);
            paintTex = cloned;
         }
         
         if (paintNormalMap)
            renderer.material.SetTexture("_BumpMap", paintTex);
         else
            renderer.material.mainTexture = paintTex;
      }
   }
   
   return paintTex;
}

// Attach this script to a camera and it will paint black pixels in 3D
// on whatever the user clicks. Make sure the mesh you want to paint
// on has a mesh collider attached.
function Update () {
   // Only when we press the mouse
   if (!Input.GetMouseButton (0))
      return;
   
   // Only if we hit something, do we continue
   var hit : RaycastHit;
   if (!Physics.Raycast (Camera.main.ScreenPointToRay(Input.mousePosition), hit))
      return;
   
   // Just in case, also make sure the collider has a renderer,
   // material and texture. Also we should ignore primitive colliders.
   var renderer : Renderer = hit.collider.renderer;
   var meshCollider = hit.collider as MeshCollider;
   if (renderer == null || renderer.sharedMaterial == null || meshCollider == null)
      return;
   
   var paintTex : Texture2D = GrabTexture(renderer);
   // And just apply those pixels   
   if (paintTex != null)   
      ApplyDecal(hit.textureCoord, paintTex);
}

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shawnpigott



Joined: 28 Sep 2005
Posts: 213
Location: Vancouver Island Canada
PostPosted: Fri Oct 31, 2008 10:58 pm    Post subject: Reply with quote
This is great. I haven't tested it with 2.1 yet but (technically) it's exactly what I was looking for. Thanks for the help.
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shawnpigott



Joined: 28 Sep 2005
Posts: 213
Location: Vancouver Island Canada
PostPosted: Sat Nov 01, 2008 8:06 am    Post subject: Reply with quote
I would appreciate some help with modifying the above script. I'm trying to get it to do the opposite of what it is currently doing. Instead of painting a new texture onto an object, I want to paint an alpha map onto an object so that you can see through it. Think scraping frost off of a window.

I think the code that needs modified is in this section.

Code:
   // Paint the pixels
   // We use the alpha of the decal to fade in the decal smoothly
   for (var i=0;i<srcPixels.Length;i++)
   {
      var blendFactor = decalPixels[i].a * opacity;
      var targetColor = tintColor * decalPixels[i];
      srcPixels[i] = Color.Lerp(srcPixels[i], targetColor, blendFactor);
   }
   
   // Apply the pixels
   target.SetPixels(minx, miny, maxX - minx, maxY - miny, srcPixels);
   target.Apply();


I've been playing with it but have had with no success so far.
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