///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2004, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
//
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///////////////////////////////////////////////////////////////////////////
#ifndef INCLUDED_IMF_ENVMAP_H
#define INCLUDED_IMF_ENVMAP_H
//-----------------------------------------------------------------------------
//
// Environment maps
//
// Environment maps define a mapping from 3D directions to 2D
// pixel space locations. Environment maps are typically used
// in 3D rendering, for effects such as quickly approximating
// how shiny surfaces reflect their environment.
//
// Environment maps can be stored in scanline-based or in tiled
// OpenEXR files. The fact that an image is an environment map
// is indicated by the presence of an EnvmapAttribute whose name
// is "envmap". (Convenience functions to access this attribute
// are defined in header file ImfStandardAttributes.h.)
// The attribute's value defines the mapping from 3D directions
// to 2D pixel space locations.
//
// This header file defines the set of possible EnvmapAttribute
// values.
//
// For each possible EnvmapAttribute value, this header file also
// defines a set of convienience functions to convert between 3D
// directions and 2D pixel locations.
//
// Most of the convenience functions defined below require a
// dataWindow parameter. For scanline-based images, and for
// tiled images with level mode ONE_LEVEL, the dataWindow
// parameter should be set to the image's data window, as
// defined in the image header. For tiled images with level
// mode MIPMAP_LEVELS or RIPMAP_LEVELS, the data window of the
// image level that is being accessed should be used instead.
// (See the dataWindowForLevel() methods in ImfTiledInputFile.h
// and ImfTiledOutputFile.h.)
//
//-----------------------------------------------------------------------------
#include "ImathBox.h"
namespace Imf {
//--------------------------------
// Supported environment map types
//--------------------------------
enum Envmap
{
ENVMAP_LATLONG = 0, // Latitude-longitude environment map
ENVMAP_CUBE = 1, // Cube map
NUM_ENVMAPTYPES // Number of different environment map types
};
//-------------------------------------------------------------------------
// Latitude-Longitude Map:
//
// The environment is projected onto the image using polar coordinates
// (latitude and longitude). A pixel's x coordinate corresponds to
// its longitude, and the y coordinate corresponds to its latitude.
// Pixel (dataWindow.min.x, dataWindow.min.y) has latitude +pi/2 and
// longitude +pi; pixel (dataWindow.max.x, dataWindow.max.y) has
// latitude -pi/2 and longitude -pi.
//
// In 3D space, latitudes -pi/2 and +pi/2 correspond to the negative and
// positive y direction. Latitude 0, longitude 0 points into positive
// z direction; and latitude 0, longitude pi/2 points into positive x
// direction.
//
// The size of the data window should be 2*N by N pixels (width by height),
// where N can be any integer greater than 0.
//-------------------------------------------------------------------------
namespace LatLongMap
{
//----------------------------------------------------
// Convert a 3D direction to a 2D vector whose x and y
// components represent the corresponding latitude
// and longitude.
//----------------------------------------------------
Imath::V2f latLong (const Imath::V3f &direction);
//--------------------------------------------------------
// Convert the position of a pixel to a 2D vector whose
// x and y components represent the corresponding latitude
// and longitude.
//--------------------------------------------------------
Imath::V2f latLong (const Imath::Box2i &dataWindow,
const Imath::V2f &pixelPosition);
//-------------------------------------------------------------
// Convert a 2D vector, whose x and y components represent
// longitude and latitude, into a corresponding pixel position.
//-------------------------------------------------------------
Imath::V2f pixelPosition (const Imath::Box2i &dataWindow,
const Imath::V2f &latLong);
//-----------------------------------------------------
// Convert a 3D direction vector into a corresponding
// pixel position. pixelPosition(dw,dir) is equivalent
// to pixelPosition(dw,latLong(dw,dir)).
//-----------------------------------------------------
Imath::V2f pixelPosition (const Imath::Box2i &dataWindow,
const Imath::V3f &direction);
//--------------------------------------------------------
// Convert the position of a pixel in a latitude-longitude
// map into a corresponding 3D direction.
//--------------------------------------------------------
Imath::V3f direction (const Imath::Box2i &dataWindow,
const Imath::V2f &pixelPosition);
}
//--------------------------------------------------------------
// Cube Map:
//
// The environment is projected onto the six faces of an
// axis-aligned cube. The cube's faces are then arranged
// in a 2D image as shown below.
//
// 2-----------3
// / /|
// / / | Y
// / / | |
// 6-----------7 | |
// | | | |
// | | | |
// | 0 | 1 *------- X
// | | / /
// | | / /
// | |/ /
// 4-----------5 Z
//
// dataWindow.min
// /
// /
// +-----------+
// |3 Y 7|
// | | |
// | | |
// | ---+---Z | +X face
// | | |
// | | |
// |1 5|
// +-----------+
// |6 Y 2|
// | | |
// | | |
// | Z---+--- | -X face
// | | |
// | | |
// |4 0|
// +-----------+
// |6 Z 7|
// | | |
// | | |
// | ---+---X | +Y face
// | | |
// | | |
// |2 3|
// +-----------+
// |0 1|
// | | |
// | | |
// | ---+---X | -Y face
// | | |
// | | |
// |4 Z 5|
// +-----------+
// |7 Y 6|
// | | |
// | | |
// | X---+--- | +Z face
// | | |
// | | |
// |5 4|
// +-----------+
// |2 Y 3|
// | | |
// | | |
// | ---+---X | -Z face
// | | |
// | | |
// |0 1|
// +-----------+
// /
// /
// dataWindow.max
//
// The size of the data window should be N by 6*N pixels
// (width by height), where N can be any integer greater
// than 0.
//
//--------------------------------------------------------------
//------------------------------------
// Names for the six faces of the cube
//------------------------------------
enum CubeMapFace
{
CUBEFACE_POS_X, // +X face
CUBEFACE_NEG_X, // -X face
CUBEFACE_POS_Y, // +Y face
CUBEFACE_NEG_Y, // -Y face
CUBEFACE_POS_Z, // +Z face
CUBEFACE_NEG_Z // -Z face
};
namespace CubeMap
{
//---------------------------------------------
// Width and height of a cube's face, in pixels
//---------------------------------------------
int sizeOfFace (const Imath::Box2i &dataWindow);
//------------------------------------------
// Compute the region in the environment map
// that is covered by the specified face.
//------------------------------------------
Imath::Box2i dataWindowForFace (CubeMapFace face,
const Imath::Box2i &dataWindow);
//----------------------------------------------------
// Convert the coordinates of a pixel within a face
// [in the range from (0,0) to (s-1,s-1), where
// s == sizeOfFace(dataWindow)] to pixel coordinates
// in the environment map.
//----------------------------------------------------
Imath::V2f pixelPosition (CubeMapFace face,
const Imath::Box2i &dataWindow,
Imath::V2f positionInFace);
//--------------------------------------------------------------
// Convert a 3D direction into a cube face, and a pixel position
// within that face.
//
// If you have a 3D direction, dir, the following code fragment
// finds the position, pos, of the corresponding pixel in an
// environment map with data window dw:
//
// CubeMapFace f;
// V2f pif, pos;
//
// faceAndPixelPosition (dir, dw, f, pif);
// pos = pixelPosition (f, dw, pif);
//
//--------------------------------------------------------------
void faceAndPixelPosition (const Imath::V3f &direction,
const Imath::Box2i &dataWindow,
CubeMapFace &face,
Imath::V2f &positionInFace);
// --------------------------------------------------------
// Given a cube face and a pixel position within that face,
// compute the corresponding 3D direction.
// --------------------------------------------------------
Imath::V3f direction (CubeMapFace face,
const Imath::Box2i &dataWindow,
const Imath::V2f &positionInFace);
}
} // namespace Imf
#endif