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This new API takes advantage of the recently imported Mesa code to support inverse matrix calculation. The matrix code keeps track (via internal flags) of the transformations a matrix represents so that it can select an optimized inversion function. Note: although other aspects of the Cogl matrix API have followed a similar style to Cairo's matrix API we haven't added a cogl_matrix_invert API because the inverse of a CoglMatrix is actually cached as part of the CoglMatrix structure meaning a destructive API like cogl_matrix_invert doesn't let users take advantage of this caching design.
312 lines
9.5 KiB
C
312 lines
9.5 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2008,2009 Intel Corporation.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*
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* Authors:
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* Robert Bragg <robert@linux.intel.com>
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*/
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#ifndef __COGL_MATRIX_H
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#define __COGL_MATRIX_H
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#include <glib.h>
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G_BEGIN_DECLS
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/**
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* SECTION:cogl-matrix
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* @short_description: Fuctions for initializing and manipulating 4x4
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* matrices.
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*
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* Matrices are used in Cogl to describe affine model-view transforms, texture
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* transforms, and projective transforms. This exposes a utility API that can
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* be used for direct manipulation of these matrices.
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*/
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typedef struct _CoglMatrix CoglMatrix;
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/**
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* CoglMatrix:
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*
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* A CoglMatrix holds a 4x4 transform matrix. This is a single precision,
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* column-major matrix which means it is compatible with what OpenGL expects.
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*
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* A CoglMatrix can represent transforms such as, rotations, scaling,
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* translation, sheering, and linear projections. You can combine these
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* transforms by multiplying multiple matrices in the order you want them
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* applied.
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*
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* The transformation of a vertex (x, y, z, w) by a CoglMatrix is given by:
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*
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* |[
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* x_new = xx * x + xy * y + xz * z + xw * w
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* y_new = yx * x + yy * y + yz * z + yw * w
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* z_new = zx * x + zy * y + zz * z + zw * w
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* w_new = wx * x + wy * y + wz * z + ww * w
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* ]|
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*
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* Where w is normally 1
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*
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* <note>You must consider the members of the CoglMatrix structure read only,
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* and all matrix modifications must be done via the cogl_matrix API. This
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* allows Cogl to annotate the matrices internally. Violation of this will give
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* undefined results. If you need to initialize a matrix with a constant other
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* than the identity matrix you can use cogl_matrix_init_from_array().</note>
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*/
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struct _CoglMatrix
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{
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/*< private >*/
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/* column 0 */
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float xx;
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float yx;
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float zx;
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float wx;
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/* column 1 */
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float xy;
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float yy;
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float zy;
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float wy;
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/* column 2 */
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float xz;
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float yz;
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float zz;
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float wz;
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/* column 3 */
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float xw;
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float yw;
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float zw;
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float ww;
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/* Note: we may want to extend this later with private flags
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* and a cache of the inverse transform matrix. */
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float inv[16];
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gulong type;
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gulong flags;
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gulong _padding3;
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};
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/**
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* cogl_matrix_init_identity:
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* @matrix: A 4x4 transformation matrix
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*
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* Resets matrix to the identity matrix:
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* <programlisting>
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* .xx=1; .xy=0; .xz=0; .xw=0;
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* .yx=0; .yy=1; .yz=0; .yw=0;
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* .zx=0; .zy=0; .zz=1; .zw=0;
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* .wx=0; .wy=0; .wz=0; .ww=1;
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* </programlisting>
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*/
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void cogl_matrix_init_identity (CoglMatrix *matrix);
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/**
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* cogl_matrix_multiply:
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* @result: The address of a 4x4 matrix to store the result in
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* @a: A 4x4 transformation matrix
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* @b: A 4x4 transformation matrix
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*
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* This function multiples the two supplied matricies together and stores
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* the result in @result
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*/
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void cogl_matrix_multiply (CoglMatrix *result,
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const CoglMatrix *a,
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const CoglMatrix *b);
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/**
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* cogl_matrix_rotate:
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* @matrix: A 4x4 transformation matrix
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* @angle: The angle you want to rotate in degrees
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* @x: X component of your rotation vector
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* @y: Y component of your rotation vector
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* @z: Z component of your rotation vector
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*
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* This function multiples your matrix with a rotation matrix that applies
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* a rotation of #angle degrees around the specified 3D vector.
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*/
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void cogl_matrix_rotate (CoglMatrix *matrix,
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float angle,
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float x,
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float y,
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float z);
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/* cogl_matrix_translate:
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* @matrix: A 4x4 transformation matrix
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* @x: The X translation you want to apply
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* @y: The Y translation you want to apply
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* @z: The Z translation you want to apply
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*
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* This function multiples your matrix with a transform matrix that translates
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* along the X, Y and Z axis.
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*/
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void cogl_matrix_translate (CoglMatrix *matrix,
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float x,
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float y,
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float z);
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/**
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* cogl_matrix_scale:
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* @matrix: A 4x4 transformation matrix
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* @sx: The X scale factor
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* @sy: The Y scale factor
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* @sz: The Z scale factor
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*
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* This function multiples your matrix with a transform matrix that scales
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* along the X, Y and Z axis.
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*/
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void cogl_matrix_scale (CoglMatrix *matrix,
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float sx,
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float sy,
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float sz);
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/**
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* cogl_matrix_frustum:
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* @matrix: A 4x4 transformation matrix
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* @left: coord of left vertical clipping plane
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* @right: coord of right vertical clipping plane
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* @bottom: coord of bottom horizontal clipping plane
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* @top: coord of top horizontal clipping plane
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* @z_near: positive distance to near depth clipping plane
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* @z_far: positive distance to far depth clipping plane
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*
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* Multiplies the matrix by the given frustum perspective matrix.
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*/
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void cogl_matrix_frustum (CoglMatrix *matrix,
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float left,
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float right,
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float bottom,
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float top,
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float z_near,
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float z_far);
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/**
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* cogl_matrix_perspective:
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* @matrix: A 4x4 transformation matrix
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* @fov_y: A field of view angle for the Y axis
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* @aspect: The ratio of width to height determining the field of view angle
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* for the x axis.
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* @z_near: The distance to the near clip plane.
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* Never pass 0 and always pass a positive number.
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* @z_far: The distance to the far clip plane. (Should always be positive)
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*
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* Multiplies the matrix by the described perspective matrix
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*
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* Note: you should be careful not to have to great a @z_far / @z_near ratio
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* since that will reduce the effectiveness of depth testing since there wont
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* be enough precision to identify the depth of objects near to each other.
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*/
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void
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cogl_matrix_perspective (CoglMatrix *matrix,
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float fov_y,
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float aspect,
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float z_near,
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float z_far);
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/**
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* cogl_matrix_ortho:
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* @matrix: A 4x4 transformation matrix
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* @left: The coordinate for the left clipping plane
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* @right: The coordinate for the right clipping plane
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* @bottom: The coordinate for the bottom clipping plane
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* @top: The coordinate for the top clipping plane
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* @z_near: The coordinate for the near clipping plane (may be negative if
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* the plane is behind the viewer)
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* @z_far: The coordinate for the far clipping plane (may be negative if
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* the plane is behind the viewer)
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*
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* Multiples the matrix by a parallel projection matrix.
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*/
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void
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cogl_matrix_ortho (CoglMatrix *matrix,
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float left,
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float right,
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float bottom,
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float top,
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float z_near,
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float z_far);
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/**
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* cogl_matrix_init_from_array:
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* @matrix: A 4x4 transformation matrix
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* @array: A linear array of 16 floats (column-major order)
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*
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* This initialises @matrix with the contents of @array
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*/
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void cogl_matrix_init_from_array (CoglMatrix *matrix, const float *array);
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/**
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* cogl_matrix_get_array:
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* @matrix: A 4x4 transformation matrix
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*
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* This casts a CoglMatrix to a float array which can be directly passed to
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* OpenGL.
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*
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* Return value: a pointer to the float array
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*/
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G_CONST_RETURN float *cogl_matrix_get_array (const CoglMatrix *matrix);
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/**
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* cogl_matrix_get_inverse:
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* @matrix: A 4x4 transformation matrix
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* @inverse: The destination for a 4x4 inverse transformation matrix
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*
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* This gets the inverse transform of a given matrix and uses it to initialize
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* a new CoglMatrix.
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*
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* Note: that although the first parameter is annotated as const to indicate
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* that the transform it represents isn't modified this function may
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* technically save a copy of the inverse transform within the given CoglMatrix
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* so that subsequent requests for the inverse transform may avoid costly
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* inversion calculations.
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*
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* Returns TRUE if the inverse was successfully calculated or FALSE for
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* degenerate transformations that can't be inverted (in this case the matrix
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* will simply be initialized with the identity matrix)
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*/
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gboolean
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cogl_matrix_get_inverse (const CoglMatrix *matrix, CoglMatrix *inverse);
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/**
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* cogl_matrix_transform_point:
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* @matrix: A 4x4 transformation matrix
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* @x: The X component of your points position [in:out]
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* @y: The Y component of your points position [in:out]
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* @z: The Z component of your points position [in:out]
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* @w: The W component of your points position [in:out]
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*
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* This transforms a point whos position is given and returned
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* as four float components.
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*/
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void
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cogl_matrix_transform_point (const CoglMatrix *matrix,
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float *x,
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float *y,
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float *z,
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float *w);
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G_END_DECLS
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#endif /* __COGL_MATRIX_H */
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