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