Class TTerrainSceneNode

DescriptionHierarchyFieldsMethodsProperties

Unit

Irrlicht

Declaration

type TTerrainSceneNode = class(TSceneNode)

Description

A scene node for displaying terrain using the geo mip map algorithm.
The code for the TerrainSceneNode is based on the Terrain renderer by Soconne and the GeoMipMapSceneNode developed by Spintz. They made their code available for Irrlicht and allowed it to be distributed under this licence. I only modified some parts. A lot of thanks go to them.
This scene node is capable of very quickly loading terrains and updating the indices at runtime to enable viewing very large terrains. It uses a CLOD (Continuous Level of Detail) algorithm which updates the indices for each patch based on a LOD (Level of Detail) which is determined based on a patch's distance from the camera.
The Patch Size of the terrain must always be a size of ( 2ˆN+1, i.e. 8+1(9), 16+1(17), etc. ). The MaxLOD available is directly dependent on the patch size of the terrain. LOD 0 contains all of the indices to draw all the triangles at the max detail for a patch. As each LOD goes up by 1 the step taken, in generating indices increases by - 2ˆLOD, so for LOD 1, the step taken is 2, for LOD 2, the step taken is 4, LOD 3 - 8, etc. The step can be no larger than the size of the patch, so having a LOD of 8, with a patch size of 17, is asking the algoritm to generate indices every 2ˆ8 ( 256 ) vertices, which is not possible with a patch size of 17. The maximum LOD for a patch size of 17 is 2ˆ4 ( 16 ). So, with a MaxLOD of 5, you'll have LOD 0 ( full detail ), LOD 1 ( every 2 vertices ), LOD 2 ( every 4 vertices ), LOD 3 ( every 8 vertices ) and LOD 4 ( every 16 vertices ).

Hierarchy

Overview

Methods

Public function GetBoundingBox(PatchX, PatchZ: LongInt): TBoundingBox; inline;
Public function GetCurrentLODOfPatches: TLongIntArray; inline;
Public function GetHeight(X, Z: Single): Single; inline;
Public function GetIndicesForPatch(PatchX, PatchZ, LOD: LongInt): TLongWordArray; inline;
Public function GetMesh: TMesh; inline;
Public function GetRenderBuffer: TMeshBuffer; inline;
Public function LoadHeightMap(RFile: TReadFile; VertexColor: TARGBColor = $ffffffff; SmoothFactor: LongInt = 0): Boolean; inline;
Public function LoadHeightMapRaw(RFile: TReadFile; BitsPerPixel: LongInt = 16; SignedData: Boolean = False; FloatVals: Boolean = False; Width: LongInt = 0; VertexColor: TARGBColor = $ffffffff; SmoothFactor: LongInt = 0): Boolean; inline;
Public function OverrideLODDistance(LOD: LongInt; NewDistance: Double): Boolean; inline;
Public procedure GetMeshBufferForLOD(Buffer: TDynamicMeshBuffer; LOD: LongInt); inline;
Public procedure ScaleTexture(Scale: Single = 1; Scale2: Single = 0); inline;
Public procedure SetCameraMovementDelta(Delta: Single); inline;
Public procedure SetCameraRotationDelta(Delta: Single); inline;
Public procedure SetDynamicSelectorUpdate(Update: Boolean); inline;
Public procedure SetLODOfPatch(PatchX, PatchZ, LOD: LongInt); inline;

Properties

Public property IndexCount: LongWord read GetIndexCount;
Public property TerrainCenter: TVector3D read GetTerrainCenter;

Description

Methods

Public function GetBoundingBox(PatchX, PatchZ: LongInt): TBoundingBox; inline;

Gets the bounding box of a patch.

Parameters
PatchX
Patch X coordinate.
PatchZ
Patch Z coordinate.
Returns

The bounding box.

Public function GetCurrentLODOfPatches: TLongIntArray; inline;

Returns an array containing the current LOD of each patch.

Public function GetHeight(X, Z: Single): Single; inline;

Returns the height of a point in the terrain.

Public function GetIndicesForPatch(PatchX, PatchZ, LOD: LongInt): TLongWordArray; inline;

Returns the indices for a specified patch at a specified Level of Detail.

Parameters
PatchX
Patch X coordinate.
PatchZ:
Patch Z coordinate.
LOD
The level of detail to get for that patch. If -1, then get the CurrentLOD. If the CurrentLOD is set to -1, meaning it's not shown, then it will retrieve the triangles at the highest LOD (0).
Public function GetMesh: TMesh; inline;

Returns the terrain mesh.

Public function GetRenderBuffer: TMeshBuffer; inline;

Returns the buffer used by the terrain. Usually used internally.

Public function LoadHeightMap(RFile: TReadFile; VertexColor: TARGBColor = $ffffffff; SmoothFactor: LongInt = 0): Boolean; inline;

Initializes the terrain data. Loads the vertices from the RFile.
The file must contain a loadable image of the heightmap. The heightmap must be square.

Parameters
RFile
The file to read the image from. File is not rewinded.
VertexColor
Color of all vertices.
SmoothFactor
Number of smoothing passes.
Public function LoadHeightMapRaw(RFile: TReadFile; BitsPerPixel: LongInt = 16; SignedData: Boolean = False; FloatVals: Boolean = False; Width: LongInt = 0; VertexColor: TARGBColor = $ffffffff; SmoothFactor: LongInt = 0): Boolean; inline;

Initializes the terrain data. Loads the vertices from the RFile.
The data is interpreted as (signed) integers of the given bit size or floats (with 32bits, signed). Allowed bitsizes for integers are 8, 16, and 32. The heightmap must be square.

Parameters
RFile
The file to read the RAW data from. File is not rewinded.
BitsPerPixel
Size of data if integers used, for floats always use 32.
SignedData
Whether we use signed or unsigned ints, ignored for floats.
FloatVals
Whether the data is float or int.
Width
Width (and also Height, as it must be square) of the heightmap. Use 0 for autocalculating from the filesize.
VertexColor
Color of all vertices.
SmoothFactor
Number of smoothing passes.
Public function OverrideLODDistance(LOD: LongInt; NewDistance: Double): Boolean; inline;

Override the default generation of distance thresholds.
For determining the LOD a patch is rendered at. If any LOD is overridden, then the scene node will no longer apply scaling factors to these values. If you override these distances, and then apply a scale to the scene node, it is your responsibility to update the new distances to work best with your new terrain size.

Public procedure GetMeshBufferForLOD(Buffer: TDynamicMeshBuffer; LOD: LongInt); inline;

Fetches the meshbuffer data based on a specified level of detail.

Parameters
Buffer
The target TDynamicMeshBuffer object.
LOD
The level of detail you want the indices from.
Public procedure ScaleTexture(Scale: Single = 1; Scale2: Single = 0); inline;

Scales the base texture, similar to makePlanarTextureMapping.

Parameters
Scale
The scaling amount. Values above 1.0 increase the number of time the texture is drawn on the terrain. Values below 0 will decrease the number of times the texture is drawn on the terrain. Using negative values will flip the texture, as well as still scaling it.
Scale2
If set to 0 (default value), this will set the second texture coordinate set to the same values as in the first set. If this is another value than zero, it will scale the second texture coordinate set by this value.
Public procedure SetCameraMovementDelta(Delta: Single); inline;

Sets the movement camera threshold.
It is used to determine when to recalculate indices for the scene node. The default value is 10.0f.

Public procedure SetCameraRotationDelta(Delta: Single); inline;

Sets the rotation camera threshold.
It is used to determine when to recalculate indices for the scene node. The default value is 1.0f.

Public procedure SetDynamicSelectorUpdate(Update: Boolean); inline;

Sets whether or not the node should dynamically update its associated selector when the geomipmap data changes.

Parameters
Update
Boolean value representing whether or not to update selector dynamically.
Public procedure SetLODOfPatch(PatchX, PatchZ, LOD: LongInt); inline;

Manually sets the LOD of a patch.

Parameters
PatchX
Patch x coordinate.
PatchZ
Patch z coordinate.
LOD
The level of detail to set the patch to.

Properties

Public property IndexCount: LongWord read GetIndexCount;

The number of indices currently in the mesh buffer.

Public property TerrainCenter: TVector3D read GetTerrainCenter;

The terrain's center.

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