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====== Loading terrain ======

Gorilla3D provides a simple terrain component for generation from height-map image. Besides the default usage, different procedural builders are available: diamond square, mandelbrot, perlin-noise (linear, cosine and cubic), plateau algorithms. The resolution / number of vertices is configurable.


For detailed information about the component and its methods, check out: Gorilla.Terrain


===== Creating a terrain at runtime from heightmap =====

<file pascal Form1.pas>
uses
  Gorilla.Terrain,
  Gorilla.Material.Lambert;

procedure TForm1.FormCreate(Sender: TObject);
var LTexturePath : String;
begin
  LTexturePath := IncludeTrailingPathDelimiter(ExtractFilePath(ParamStr(0)));
  
  FTerrain := TGorillaTerrain.Create(fGorilla);
  FTerrain.Parent := FGorillaViewport;
  
  // set resolution of terrain to 256 x 256 sections
  // this generates 65.536 cells with 131.072 triangles and 393.216 vertices.
  FTerrain.ResolutionX := 256;
  FTerrain.ResolutionY := 256;
  
  // here we load the height map image
  FTerrain.HeightMap.LoadFromFile(LTexturePath + 'terrain-h.jpg');
  
  // adjust terrain size and scaling
  FTerrain.HeightScale := 10;
  FTerrain.Scale.X := 100;
  FTerrain.Scale.Y := 10;
  FTerrain.Scale.Z := 100;

  // build terrain mesh from previously loaded heightmap
  // 1st param: static buffering for large number of vertices.
  // 2nd param: decimation disabled
  FTerrain.RebuildTerrain(true, false);

  // apply a material as texture to it
  FTerrainMaterial := TGorillaLambertMaterialSource.Create(FTerrain);
  FTerrainMaterial.Parent := FTerrain;
  FTerrainMaterial.Texture.LoadFromFile(LTexturePath + 'terrain-c.jpg');
  FTerrain.MaterialSource := FTerrainMaterial;
end;
</file>
				

===== Creating a terrain at runtime by procedural method =====

<file pascal Form1.pas>
uses
  Gorilla.Terrain,
  Gorilla.Material.Lambert;

procedure TForm1.FormCreate(Sender: TObject);
var LTexturePath : String;
begin
  LTexturePath := IncludeTrailingPathDelimiter(ExtractFilePath(ParamStr(0)));
  
  FTerrain := TGorillaTerrain.Create(fGorilla);
  FTerrain.Parent := FGorillaViewport;
  
  // set resolution of terrain to 256 x 256 sections
  // this generates 65.536 cells with 131.072 triangles and 393.216 vertices.
  FTerrain.ResolutionX := 256;
  FTerrain.ResolutionY := 256;
  
  // adjust terrain size and scaling
  FTerrain.HeightScale := 10;
  FTerrain.Scale.X := 100;
  FTerrain.Scale.Y := 10;
  FTerrain.Scale.Z := 100;

  // build a random terrain by a predefined procedural algorithm
  FTerrain.RandomTerrain(TRandomTerrainAlgorithmType.DiamondSquare);

  // apply a material as texture to it
  FTerrainMaterial := TGorillaLambertMaterialSource.Create(FTerrain);
  FTerrainMaterial.Parent := FTerrain;
  FTerrainMaterial.Texture.LoadFromFile(LTexturePath + 'terrain-c.jpg');
  FTerrain.MaterialSource := FTerrainMaterial;
end;
</file>
				
__NOTICE:__ Once you build a random terrain, you are able to store the heightmap bitmap and reload later. 

==== Implemented terrain algorithms ====


^ Algorithm ^ Notice ^
| Hill | A basic procedural hill algorithm. The algorithm will produce smooth hills by radius settings and a given count. | 
| DiamondSquare | A very popular algorithm to build random terrain. The algorithm creates randomly lows and highs for a realisic terrain. | 
| Mandelbrot | Creates the typical mandelbrot pattern: https://en.wikipedia.org/wiki/Mandelbrot_set This is a fixed result, but you could use this as basis for further computation. | 
| PerlinNoise | Perlin noise terrains are a good choice for random terrain. The component provides different mathmatical interpolation methods (linear, cosine, cubic). | 
| Plateau | A plateau terrain is described by a specific number of high and flat areas,  while the rest is much lower. The algorithm extends the TDiamondSquareTerrain. | 
| Brownian | Brownian terrains or brownian surface is based on the diamond square based terrain algorithm: https://en.wikipedia.org/wiki/Brownian_surface The component computes peaks by a specific number of random particles. Afterwards the complete terrain will be smooth to create a realistic landscape. | 

===== Creating an individual procedural terrain algorithm =====

You can also develop your own procedural algorithm by extending TRandomTerrainAlgorithm or any descendant. In the example below, we generate a random terrain: 

<file pascal MyTerrainAlg.pas>
type
  TMyTerrainAlgorithm = class(TRandomTerrainAlgorithm)
    protected
      procedure Generate();
    public
      function GetHeightMap() : TBitmap; override;    
  end;  
  
{ TMyTerrainAlgorithm }


procedure TMyTerrainAlgorithm.Generate();
var x, z: Integer;
       i : Integer;
begin
  System.SetLength(FData, 256);
  for i := 0 to High(FData) do
    System.SetLength(FData[i], 256);
    
  for x := 0 to 255 do
    for z := 0 to 255 do
    begin
      FData[x, z] := Random(100) / 100;
    end;
end;

function TMyTerrainAlgorithm.GetHeightMap() : TBitmap;
begin
  Generate();

  result := inherited;
end;
			
LMyTerrainAlgorithm := TMyTerrainAlgorithm.Create();
try
  FTerrain.RandomTerrain(LMyTerrainAlgorithm);
finally
  FreeAndNil(LMyTerrainAlgorithm);
end;
</file>

===== Resolution =====
It is recommend to use 2 ^ X resolution sizes for your terrain.
Set resolution by the published properties "ResolutionX" and "ResolutionY".

The table below lists common terrain sizes and their resulting vertices.

^ Size ^ Vertex-Count ^ Index-Count ^ Triangles ^ Memory-Size ^
| 16 x 16 | 289 | 1536 | 512 | 26.952 Bytes |
| 32 x 32 | 1089 | 6144 | 2048 | 102.984 Bytes |
| 64 x 64| 4225 | 24.576 | 8192 | 402.504 Bytes |
| 128 x 128 | 16.641 | 98.304 | 32.768 | 1.591.368 Bytes |
| 256 x 256 | 66.049 | 393.216 | 131.072 | 6.328.392 Bytes |
| 512 x 512 | 263.169 | 1.572.864 | 524.288 | 25.239.624 Bytes |
| 1024 x 1024 | 1.050.625 | 6.291.456 | 2.097.152 | 100.810.824 Bytes |
| 2048 x 2048 | 4.198.401 | 25.165.824 | 8.388.608 | 402.948.168 Bytes |

__Notice:__ When using terrain on Android, remember the 16-Bit vertex and index limitation.
You are allowed to use at max 65536 indices per mesh on Android systems.
===== Smoothing =====

In case you are using a height-map smaller than your terrain-resolution, the resulting terrain could show some unlovely steps.
Therefore the component provides the published "Smoothing" property. Set a value between 1 and 20 to apply smoothing algorithm onto your heightmap. A value of zero means that smoothing is deactivated.

===== Decimation =====

Due to optimization reasons the component provides an **experimental** decimation algorithm.

<file pascal>
// 1st parameter - static buffering of vertex data
// 2nd parameter - decimation algorithm execution
FTerrain.RebuildTerrain(true, >>>true<<<);
</file>

Generating a procedural terrain by algorithm, activate decimation like this:

<file pascal>
// 1st parameter - type of terrain algorithm
// 2nd parameter - static buffering of vertex data
// 3rd parameter - decimation algorithm execution
FTerrain.RandomTerrain(TRandomTerrainAlgorithmType.DiamondSquare, true, >>>true<<<);
</file>

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