08932584b5
This is useful because sometimes we need to get the current matrix, which is too expensive when indirect rendering. In addition, this virtualization makes it easier to clean up the API in the future.
215 lines
5.9 KiB
C
215 lines
5.9 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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* 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().
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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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float _padding0[16];
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gulong _padding1;
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gulong _padding2;
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gulong _padding3;
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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_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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* @near: positive distance to near depth clipping plane
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* @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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*/
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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_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_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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const float *cogl_matrix_get_array (const CoglMatrix *matrix);
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G_END_DECLS
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#endif /* __COGL_MATRIX_H */
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