create readable colour map

Question

Hi =]

I want to output my 2D array to a texture, then read that texture back later to populate that array with the same information

So (thanks to Unity Answers) I have the save part of the script (The chunk of script at the end of the question). Now that part seems to be working excellently, the console returns nice values that are multiples of 0.02

Here is an output for a simple 4x4 map (scaled of course!) :

alt text

ok, so now for my reader. It does not return nice friendly values that are multiples of 0.02 at all :

 // me =]
 
 function ReadFromTexture()
 {
     // reset lists
     tileHeight = new int[ heightTexture.width, heightTexture.height ];
     
     Debug.Log( "gridSize H " + heightTexture.width + "," + heightTexture.height + " : T " + typeTexture.width + "," + typeTexture.height );
     
     // populate list with pixel info
     
     for ( var y : int = 0; y < heightTexture.height; y ++ ) 
     {
         for ( var x : int = 0; x < heightTexture.width; x ++ ) 
         {
             // -- HEIGHT --
             
             var heightPxlColour : Color = heightTexture.GetPixel( x, y );
             
             //var tempHeight : float = ( heightPxlColour.r + heightPxlColour.g + heightPxlColour.b ) / 3.0;
             var tempHeight : float = heightPxlColour.r;
             Debug.Log( "tempHeight = " + tempHeight );
             
             tempHeight = tempHeight * 50.0; // 1/0.02;
             Debug.Log( "tempHeight * 50 = " + tempHeight ); 
             
             tempHeight -= 10.0; // from +
             Debug.Log( "tempHeight - 10 = " + tempHeight ); 
             
             //              
             Debug.Log( " " + x + " " + y + " : tileHeight = " + tempHeight );            
             
             tileHeight[ x, y ] = parseInt( tempHeight );
         }
     }
     
     // assign all to TileManager ....
 }

I have set the Texture Import settings to :

 Advanced
 (power of 2 is greyed out, otherwise would be set to none/single)
 Read/Write enabled = true
 mode = Clamp
 max size = 32
 format = automatic truecolor

How can I generate a 'heightmap' from a 2 dimensinal array, then read that texture to return the exact same values.

The 2D array is an array of integers.

Thanks.

Write Texture Script :

 function GenerateMap() 
 {
     // Create a new texture and assign it to the renderer's material
     var texHeight = new Texture2D( tileManager.gridSize.x, tileManager.gridSize.y ); // height texture
     
     // Fill the texture information from tileHeight array
     for ( var y : int = 0; y < texHeight.height; y ++ ) 
     {
         for ( var x : int = 0; x < texHeight.width; x ++ ) 
         {
             // -- height texture --
             
             var hColor : Color;
             
             // - set the colour range -
             
             // range is based on tiles being between
             // -10 and 40 on the Y_axis
             
             var tempColour : float = 0.0;
             
             tempColour = ( parseFloat( tileHeight[ x, y ] ) + 10.0 ); // +10 makes range = 0 to 50
             
             Debug.Log( "tempColour at   height + 10 = " + tempColour );
             
             tempColour = tempColour * 0.02; // 1/50 of the position
             
             Debug.Log( "tempColour at   tempColour * 0.02 = " + tempColour );
             
             tempColour = Mathf.Clamp( tempColour, 0.0, 1.0 ); // clamp 
             
             Debug.Log( "tileHeight " + (x+(x*y)) + " " + tileHeight[ x, y ] + " : tempColour " + tempColour );
             
             hColor = Color( tempColour, 0.0, 0.0 );
             
             texHeight.SetPixel( x, y, hColor );
         }
     }
     
     // Apply all SetPixel calls
     texHeight.Apply();
     
     // save to system
     var timeStamp : String = GetSystemDateTime();
     
     SaveTextureToFile( texHeight, timeStamp + "_heightmap.png" ); // height texture
 }
 
 // http://answers.unity3d.com/questions/245600/saving-a-png-image-to-hdd-in-standalone-build.html
 
 function SaveTextureToFile( texture : Texture2D, fileName )
 {
     var bytes = texture.EncodeToPNG();
     var file = new File.Open( Application.dataPath + "/" + fileName, FileMode.Create );
     var binary = new BinaryWriter(file);
     binary.Write(bytes);
     file.Close();
 }

Edit :

Here is the test code I wrote using Set/GetPixels32. It stores ints between 0 and 255, and returns correct values from the texture :

 #pragma strict
 
 private var myArray : int[ , ];
 
 public var inputTexture : Texture2D;
 private var readArray : int[ , ];
 
 function Start() 
 {
     PopulateArray();
 }
 
 function Update() 
 {
     if ( Input.GetMouseButtonDown(0) || Input.GetKeyDown(KeyCode.F1) )
     {
         GenerateTexture();
     }
     else if ( Input.GetMouseButtonDown(1) || Input.GetKeyDown(KeyCode.F2) )
     {
         ReadTexture();
     }
 }
 
 // ----
 
 function PopulateArray() 
 {
     myArray = new int[ 4, 4 ];
     
     for ( var i:int = 0; i < 4; i ++ )
     {
         myArray[ 0, i ] = i;
         myArray[ 1, i ] = i * 20;
         myArray[ 2, i ] = i * 50;
         myArray[ 3, i ] = i * 62;
     }
 }
 
 // ----
 
 function GenerateTexture() 
 {
     var tempTexture : Texture2D = new Texture2D( 4, 4 );
     var tempColourArray : Color32[] = new Color32[ 16 ];
     var index : int = 0;
     
     for ( var y : int = 0; y < tempTexture.height; y ++ ) 
     {
         for ( var x : int = 0; x < tempTexture.width; x ++ ) 
         {
             tempColourArray[ index ++ ] = Color( myArray[ x, y ] / 255.0, 0.0, 0.0 );
         }
     }
     
     tempTexture.SetPixels32( tempColourArray, 0 );
     tempTexture.Apply( false );
     
     // save to system
     var timeStamp : String = GetSystemDateTime();
     SaveTextureToFile( tempTexture, timeStamp + "_colourmaptest.png" );
 }
 
 // ----
 
 function ReadTexture() 
 {
     var tempArray : Color32[] = inputTexture.GetPixels32( 0 );
     readArray = new int[ 4, 4 ];
     
     var success : boolean = true;
     var index : int = 0;
     
     for ( var y:int = 0; y < 4; y ++ )
     {
         for ( var x:int = 0; x < 4; x ++ )
         {
             readArray[ x, y ] = parseInt( tempArray[ index ].r * 1.0 );
             
             if ( readArray[ x, y ] != myArray[ x, y ] )
             {
                 Debug.Log( "index " + index + " mismatch at ( " + x + ", " + y + " ) : read = " + readArray[ x, y ] + " : write = " + myArray[ x, y ] );
                 success = false;
             }
             
             index ++;
         }
     }
     
     Debug.Log( "success = " + success );
 }
 
 // ----
 
 // http://answers.unity3d.com/questions/245600/saving-a-png-image-to-hdd-in-standalone-build.html
 
 function SaveTextureToFile( texture : Texture2D, fileName )
 {
     var bytes = texture.EncodeToPNG();
     var file = new File.Open( Application.dataPath + "/" + fileName, FileMode.Create );
     var binary = new BinaryWriter(file);
     binary.Write(bytes);
     file.Close();
 }
 
 // ----
 
 // Me
 
 function GetSystemDateTime() : String
 {
     // get the date time
     var tempStamp : String = System.DateTime.Now.ToString();
     // remove "/"
     var dateStampSplit : String[] = tempStamp.Split( "/"[0] );
     // remove ":"
     var timeStampSplit : String[] = dateStampSplit[2].Split( ":"[0] );
     // remove " "
     var space1split : String[] = timeStampSplit[0].Split( " "[0] );
     var space2split : String[] = timeStampSplit[2].Split( " "[0] );
     // put timeStamp together
     var timeStamp : String = "";
     timeStamp = dateStampSplit[0] + dateStampSplit[1] + space1split[0] + space1split[1] + timeStampSplit[1] + space2split[0] + space2split[1];
     return timeStamp;
 }
 
 // ----

Answer 1

Best Answer

Answer by whydoidoit · Dec 02, 2012 at 12:04 PM

So images are not stored using floating points - they are stored using bytes :) Your code is therefore:

Converting an int to a float
Messing with it
Converting back into an int (with only 255 discrete values) by writing it to an image!

You really want to be using the GetPixels32 to return the whole image as an array and then you can actually access the integers stored in the file :)

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AlucardJay · Dec 02, 2012 at 12:21 PM 0

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Thanks, as this is new ground for me, have some testing to do. Even the API says Using SetPixels32 is faster than calling SetPixels. , so shall let you know how I go with converting my 2D arrays to textures and back. (another command I was not aware of, thanks).

messing with it ... still chuckling. I get that sometimes from my colleague, or as he says doing it longhand. I thought I did ok normalizing an integer value between -10 and +40 :)

whydoidoit · Dec 02, 2012 at 12:22 PM 0

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Yeah that's why there's so much inaccuracy in the values coming back - they've been hacked around with too much. You could probably get away with it by using Mathf.RoundToInt() but it's not really the right method. We think of colours as floats in Unity - but that's really not the case anywhere but in the shader.

AlucardJay · Dec 02, 2012 at 12:50 PM 0

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thanks for the SetPixels32 help, that was a silly mistake.

AlucardJay · Dec 03, 2012 at 07:13 AM 0

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Here's what I came up with (see edit to question). Many thanks for all your help and pointers, have learned a new technique and a new command. Awesome.

AlucardJay · Dec 03, 2012 at 07:47 AM 0

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What I was having problems with ( and cannot get my head around) is that when the pixel is assigned, I divide by 255 :

 tempColourArray[ index ] = Color( myArray[ x, y ] / 255.0, 0.0, 0.0 );

when I read the pixel, it already comes back multiplied :

 readArray[ x, y ] = parseInt( tempArray[ index ].r * 1.0 );

so I write a value of value/255 and read value for the same value. I shall not question, it works.

create readable colour map

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