[Cyan]<Imaging>6.0>NewThreeDWorld>TextureMaps.mesa!9

TextureMaps.mesa

Last Edited by: Crow, May 24, 1986 12:31:49 pm PDT

DIRECTORY

Atom USING [PropList],

ScanConvert USING [Spot],

ThreeDScenes USING [Context, ShapeInstance],

Vector2 USING [VEC],

Rope USING [ROPE];

TextureMaps: CEDAR DEFINITIONS

~ BEGIN

Basic Types

TextureMapsError: SIGNAL [reason: ATOM];

Pair: TYPE ~ Vector2.VEC; -- [ x, y: REAL];

TextureMap: TYPE ~ RECORD[type: ATOM, pixels: REF ANY, props: Atom.PropList];

type: NIL, $Bump - intensity map, $Color - full color map.

Summed-Area Texture storage

IntSequence: TYPE ~ RECORD[SEQUENCE length: NAT OF INT];

ScanSequence: TYPE ~ RECORD[SEQUENCE length: NAT OF REF IntSequence];

SummedTexture: TYPE ~ RECORD[SEQUENCE length: NAT OF REF ScanSequence];

Procedures for Computing Texture Coordinates

MakeTxtrCoordsFromVtxNos: PROC[ shape: REF ThreeDScenes.ShapeInstance,

vtcesInRow, numberOfRows: NAT,

row0col0, rowNcol0, rowNcolM, row0ColM: Pair ];

For objects which are rectangular polygon grids pulled into a surface shape, eg. surfaces of revolution, this maps a texture onto the rectangular grid.

MakeTxtrCoordsFromNormals: PROC[ shape: REF ThreeDScenes.ShapeInstance,

botLeft: Pair ← [0.0, 0.0], topLeft: Pair ← [0.0, 1.0],
topRight: Pair ← [1.0, 1.0], botRight: Pair ← [1.0, 0.0],
sw: Pair ← [180.0, -90.0], nw: Pair ← [180.0, 90.0],
ne: Pair ← [-180.0, 90.0], se: Pair ← [-180.0, -90.0] ];

This takes the surface normals and maps from spherical coordinates into a rectangular texture. botLeft, topLeft, etc. allow mapping multiple, or skewed, instances of the texture onto the rectangle. longMin, longMax, etc. allow the area affected to be limited to a certain range of sperical coordinates.

Procedures for Reading and Preparing Texture Files

TextureFromAIS: PROC[context: REF ThreeDScenes.Context, fileName: Rope.ROPE,
type: ATOM ← $Intensity]
RETURNS[texture: REF TextureMap];

SetTexture: PROC[shape: REF ThreeDScenes.ShapeInstance, texture: REF TextureMap];

SumTexture: PROC[shape: REF ThreeDScenes.ShapeInstance];

Procedures for Evaluating Texture at a Spot

GetTxtrAt: PROC[smpl: ScanConvert.Spot] RETURNS[ScanConvert.Spot];

END.