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offscreen: Fix partially off-stage actors being clipped in the fbo

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If an actor was partially off of the stage, it would be clipped because
of the stage viewport. This produces problems if you use an offscreen
effect that relies on the entire actor being rendered (e.g. shadows).

Expand the viewport in this scenario so that the offscreen-rendering isn't
clipped.

This fixes http://bugzilla.clutter-project.org/show_bug.cgi?id=2550
This commit is contained in:
Chris Lord 2011-02-11 15:18:08 +00:00
parent 442d8c3f2e
commit a297fb0394
1 changed files with 42 additions and 1 deletions
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43
clutter/clutter-offscreen-effect.c
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@ -196,6 +196,7 @@ clutter_offscreen_effect_pre_paint (ClutterEffect *effect)
CoglMatrix modelview;
gfloat fbo_width, fbo_height;
gfloat width, height;
gfloat xexpand, yexpand;
if (!clutter_actor_meta_get_enabled (CLUTTER_ACTOR_META (effect)))
return FALSE;
@ -234,13 +235,53 @@ clutter_offscreen_effect_pre_paint (ClutterEffect *effect)
* framebuffer. */
clutter_actor_get_size (priv->stage, &width, &height);
clutter_actor_box_get_origin (&box, &priv->x_offset, &priv->y_offset);
cogl_set_viewport (-priv->x_offset, -priv->y_offset, width, height);
/* Expand the viewport if the actor is partially off-stage,
* otherwise the actor will end up clipped to the stage viewport
*/
xexpand = 0.f;
if (priv->x_offset < 0.f)
xexpand = -priv->x_offset;
if (priv->x_offset + fbo_width > width)
xexpand = MAX (xexpand, (priv->x_offset + fbo_width) - width);
yexpand = 0.f;
if (priv->y_offset < 0.f)
yexpand = -priv->y_offset;
if (priv->y_offset + fbo_height > height)
yexpand = MAX (yexpand, (priv->y_offset + fbo_height) - height);
/* Set the viewport */
cogl_set_viewport (-(priv->x_offset + xexpand), -(priv->y_offset + yexpand),
width + (2 * xexpand), height + (2 * yexpand));
/* Copy the stage's projection matrix across to the framebuffer */
_clutter_stage_get_projection_matrix (CLUTTER_STAGE (priv->stage),
&projection);
cogl_set_projection_matrix (&projection);
/* If we've expanded the viewport, make sure to scale the modelview
* matrix accordingly (as it's been initialised to work with the
* original viewport and not our expanded one).
*/
if (xexpand > 0.f || yexpand > 0.f)
{
CoglMatrix correction;
gfloat new_width, new_height;
new_width = width + (2 * xexpand);
new_height = height + (2 * yexpand);
cogl_matrix_init_identity (&correction);
cogl_matrix_scale (&correction,
width / new_width,
height / new_height,
1);
cogl_matrix_multiply (&correction, &correction, &modelview);
modelview = correction;
}
/* Copy the modelview that would have been used if rendering onscreen */
cogl_set_modelview_matrix (&modelview);