mesh.md

title
Polygon Meshes

Polygon Meshes

All visible game elements in a scene, whether it is a Model or a Shape, are made up of polygon meshes. JME3 has a com.jme3.scene.Mesh class that represents all meshes.

• Meshes are made up of triangles: getTriangleCount(…) and getTriangle(…)
• Each mesh has a unique ID: getId()
• Meshes have transformations: Location (local translation), rotation, scale.
• Meshes have a bounding volume. jME3 can detect intersections (that is, non-physical collisions) between meshes, or between meshes and 2D elements such as rays: collideWith().
• Meshes are locked with setStatic() and unlocked with setDynamic().
  • Static Meshes cannot be modified, but are more optimized and faster (they can be precalculated).
  • Dynamic Meshes can be modified live, but are not optimized and slower.

You have several options when creating Geometries from meshes:

• Use built-in Shapes as meshes;
• Load 3D models (that is, meshes created in external applications); or
• Create free-form custom meshes programmatically.

Vertex Buffer

The VertexBuffer contains a particular type of geometry data used by Meshes. Every VertexBuffer set on a Mesh is sent as an attribute to the vertex shader to be processed.

Mesh Vertex Buffers

Vertex Buffer Type	Description
Type.Position	Position of the vertex (3 floats)
Type.Index	Specifies the index buffer, must contain integer data.
Type.TexCoord	Texture coordinate
Type.TexCoord2	Texture coordinate #2
Type.Normal	Normal vector, normalized.
Type.Tangent	Tangent vector, normalized.
Type.Binormal	Binormal vector, normalized.
Type.Color	Color and Alpha (4 floats)
Type.Size	The size of the point when using point buffers.
Type.InterleavedData	Specifies the source data for various vertex buffers when interleaving is used.
Type.BindPosePosition	Inital vertex position, used with animation.
Type.BindPoseNormal	Inital vertex normals, used with animation
Type.BoneWeight	Bone weights, used with animation
Type.BoneIndex	Bone indices, used with animation

Mesh Properties

Mesh method	Description
setLineWidth(1)	the thickness of the line if using Mode.Lines
setPointSize(4.0f)	the thickness of the point when using Mode.Points
setBound(boundingVolume)	if you need to specifiy a custom optimized bounding volume
setStatic()	Locks the mesh so you cannot modify it anymore, thus optimizing its data (faster).
setDynamic()	Unlocks the mesh so you can modified it, but this will un-optimize the data (slower).
setMode(Mesh.Mode.Points)	Used to set mesh rendering modes, see below.
getId()	returns the Mesh ID
getTriangle(int,tri)	returns data of triangle number int into variable tri
scaleTextureCoordinates(Vector2f)	How the texture will be stretched over the whole mesh.

Mesh Rendering Modes

Mesh Mode	Description
Mesh.Mode.Points	Show only corner points (vertices) of mesh
Mesh.Mode.Lines	Show lines (edges) of mesh
Mesh.Mode.LineLoop	?
Mesh.Mode.LineStrip	?
Mesh.Mode.Triangles	?
Mesh.Mode.TriangleStrip	?
Mesh.Mode.TriangleFan	?
Mesh.Mode.Hybrid	?

Level of Detail

Optionally, custom meshes can have a LOD (level of detail optimization) that renders more or less detail, depending on the distance of the mesh from the camera. You have to specify several vertex buffers, one for each level of detail you want (very far away with few details, close up with all details, and something in the middle). Use setLodLevels(VertexBuffer[] lodLevels).

spatial, node, mesh, geometry, scenegraph