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Since the CoglMatrix type was added for supporting texture matrices recently it made sense to be consistent accross the Cogl API and use the Cogl type over the GL style GLfloat m[16] arrays.
183 lines
4.7 KiB
C
183 lines
4.7 KiB
C
#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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/**
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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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* <programlisting>
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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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* </programlisting>
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* Where w is normally 1
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*/
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typedef struct _CoglMatrix {
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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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/*< private >*/
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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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} CoglMatrix;
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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_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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/**
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* cogl_matrix_init_from_gl_matrix:
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* @matrix: A 4x4 transformation matrix
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* @gl_matrix: A linear array of 16 Glfloats (column-major)
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*
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* This initialises @matrix with the contents of @gl_matrix
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*/
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void cogl_matrix_init_from_gl_matrix (CoglMatrix *matrix, const float *gl_matrix);
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/**
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* cogl_matrix_get_gl_matrix:
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* @matrix: A 4x4 transformation matrix
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*
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* This casts a CoglMatrix to a GLfloat array which can be directly passed to
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* OpenGL.
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*/
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const float *cogl_matrix_get_gl_matrix (const CoglMatrix *matrix);
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G_END_DECLS
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#endif /* __COGL_MATRIX_H */
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