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cogl-clip-state: Export transform_point internally to Cogl

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The transform_point function takes a modelview matrix, projection
matrix and a viewport and performs all three transformations on a
point to give a Cogl window coordinate. This is useful in a number of
places in Cogl so this patch moves it to cogl.c and adds it to
cogl-internal.h
This commit is contained in:
Neil Roberts 2010-04-22 13:48:49 +01:00
parent 4abd42aced
commit a9da7d72db
3 changed files with 49 additions and 42 deletions
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45
cogl/cogl-clip-state.c
View File

@ -38,6 +38,7 @@
#include "cogl-framebuffer-private.h"
#include "cogl-journal-private.h"
#include "cogl-util.h"
#include "cogl-matrix-private.h"
void
cogl_clip_push_window_rectangle (int x_offset,
@ -76,46 +77,6 @@ cogl_clip_push_window_rect (float x_offset,
cogl_clip_push_window_rectangle (x_offset, y_offset, width, height);
}
/* Scale from OpenGL normalized device coordinates (ranging from -1 to 1)
* to Cogl window/framebuffer coordinates (ranging from 0 to buffer-size) with
* (0,0) being top left. */
#define VIEWPORT_TRANSFORM_X(x, vp_origin_x, vp_width) \
( ( ((x) + 1.0) * ((vp_width) / 2.0) ) + (vp_origin_x) )
/* Note: for Y we first flip all coordinates around the X axis while in
* normalized device coodinates */
#define VIEWPORT_TRANSFORM_Y(y, vp_origin_y, vp_height) \
( ( ((-(y)) + 1.0) * ((vp_height) / 2.0) ) + (vp_origin_y) )
/* Transform a homogeneous vertex position from model space to Cogl
* window coordinates (with 0,0 being top left) */
static void
transform_point (CoglMatrix *matrix_mv,
CoglMatrix *matrix_p,
float *viewport,
float *x,
float *y)
{
float z = 0;
float w = 1;
/* Apply the modelview matrix transform */
cogl_matrix_transform_point (matrix_mv, x, y, &z, &w);
/* Apply the projection matrix transform */
cogl_matrix_transform_point (matrix_p, x, y, &z, &w);
/* Perform perspective division */
*x /= w;
*y /= w;
/* Apply viewport transform */
*x = VIEWPORT_TRANSFORM_X (*x, viewport[0], viewport[2]);
*y = VIEWPORT_TRANSFORM_Y (*y, viewport[1], viewport[3]);
}
#undef VIEWPORT_SCALE_X
#undef VIEWPORT_SCALE_Y
/* Try to push a rectangle given in object coordinates as a rectangle in window
* coordinates instead of object coordinates */
static gboolean
@ -147,8 +108,8 @@ try_pushing_rect_as_window_rect (float x_1,
cogl_get_projection_matrix (&matrix_p);
cogl_get_viewport (v);
transform_point (&matrix, &matrix_p, v, &x_1, &y_1);
transform_point (&matrix, &matrix_p, v, &x_2, &y_2);
_cogl_transform_point (&matrix, &matrix_p, v, &x_1, &y_1);
_cogl_transform_point (&matrix, &matrix_p, v, &x_2, &y_2);
/* Consider that the modelview matrix may flip the rectangle
* along the x or y axis... */

7
cogl/cogl-internal.h
View File

@ -124,6 +124,13 @@ _cogl_flush_face_winding (void);
void
_cogl_disable_other_texcoord_arrays (const CoglBitmask *mask);
void
_cogl_transform_point (const CoglMatrix *matrix_mv,
const CoglMatrix *matrix_p,
const float *viewport,
float *x,
float *y);
#ifdef COGL_HAS_XLIB_SUPPORT
/*

39
cogl/cogl.c
View File

@ -1107,3 +1107,42 @@ cogl_set_source_color4f (float red,
cogl_set_source_color (&c);
}
/* Scale from OpenGL normalized device coordinates (ranging from -1 to 1)
* to Cogl window/framebuffer coordinates (ranging from 0 to buffer-size) with
* (0,0) being top left. */
#define VIEWPORT_TRANSFORM_X(x, vp_origin_x, vp_width) \
( ( ((x) + 1.0) * ((vp_width) / 2.0) ) + (vp_origin_x) )
/* Note: for Y we first flip all coordinates around the X axis while in
* normalized device coodinates */
#define VIEWPORT_TRANSFORM_Y(y, vp_origin_y, vp_height) \
( ( ((-(y)) + 1.0) * ((vp_height) / 2.0) ) + (vp_origin_y) )
/* Transform a homogeneous vertex position from model space to Cogl
* window coordinates (with 0,0 being top left) */
void
_cogl_transform_point (const CoglMatrix *matrix_mv,
const CoglMatrix *matrix_p,
const float *viewport,
float *x,
float *y)
{
float z = 0;
float w = 1;
/* Apply the modelview matrix transform */
cogl_matrix_transform_point (matrix_mv, x, y, &z, &w);
/* Apply the projection matrix transform */
cogl_matrix_transform_point (matrix_p, x, y, &z, &w);
/* Perform perspective division */
*x /= w;
*y /= w;
/* Apply viewport transform */
*x = VIEWPORT_TRANSFORM_X (*x, viewport[0], viewport[2]);
*y = VIEWPORT_TRANSFORM_Y (*y, viewport[1], viewport[3]);
}
#undef VIEWPORT_TRANSFORM_X
#undef VIEWPORT_TRANSFORM_Y