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clip-stack: combine modelview-projection in set_clip_planes

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When using clip planes and we we have to project some vertices into
screen coordinates we used to transform those by the modelview and then
the projection matrix separately. Now we combine the modelview and
projection matrix and then use that to transform the vertices in one
step instead.
This commit is contained in:
Robert Bragg 2010-11-22 15:51:15 +00:00
parent 649aaffbe9
commit 0ec9e406ea
1 changed files with 12 additions and 12 deletions
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24
cogl/cogl-clip-stack.c
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@ -145,20 +145,15 @@ struct _CoglClipStackPath
};
static void
project_vertex (const CoglMatrix *modelview_matrix,
const CoglMatrix *projection_matrix,
project_vertex (const CoglMatrix *modelview_projection,
float *vertex)
{
int i;
/* Apply the modelview matrix */
cogl_matrix_transform_point (modelview_matrix,
&vertex[0], &vertex[1],
&vertex[2], &vertex[3]);
/* Apply the projection matrix */
cogl_matrix_transform_point (projection_matrix,
cogl_matrix_transform_point (modelview_projection,
&vertex[0], &vertex[1],
&vertex[2], &vertex[3]);
/* Convert from homogenized coordinates */
for (i = 0; i < 4; i++)
vertex[i] /= vertex[3];
@ -234,6 +229,7 @@ set_clip_planes (float x_1,
CoglMatrixStack *projection_stack =
_cogl_framebuffer_get_projection_stack (framebuffer);
CoglMatrix projection_matrix;
CoglMatrix modelview_projection;
float signed_area;
float vertex_tl[4] = { x_1, y_1, 0, 1.0 };
@ -244,10 +240,14 @@ set_clip_planes (float x_1,
_cogl_matrix_stack_get (projection_stack, &projection_matrix);
_cogl_matrix_stack_get (modelview_stack, &modelview_matrix);
project_vertex (&modelview_matrix, &projection_matrix, vertex_tl);
project_vertex (&modelview_matrix, &projection_matrix, vertex_tr);
project_vertex (&modelview_matrix, &projection_matrix, vertex_bl);
project_vertex (&modelview_matrix, &projection_matrix, vertex_br);
cogl_matrix_multiply (&modelview_projection,
&projection_matrix,
&modelview_matrix);
project_vertex (&modelview_projection, vertex_tl);
project_vertex (&modelview_projection, vertex_tr);
project_vertex (&modelview_projection, vertex_bl);
project_vertex (&modelview_projection, vertex_br);
/* Calculate the signed area of the polygon formed by the four
vertices so that we can know its orientation */