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19b8622983
This implements a variation of frustum culling whereby we convert screen space clip rectangles into eye space mini-frustums so that we don't have to repeatedly transform actor paint-volumes all the way into screen coordinates to perform culling, we just have to apply the modelview transform and then determine each points distance from the planes that make up the clip frustum. By avoiding the projective transform, perspective divide and viewport scale for each point culled this makes culling much cheaper.
139 lines
5.8 KiB
C
139 lines
5.8 KiB
C
/*
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* Clutter.
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*
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* An OpenGL based 'interactive canvas' library.
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*
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* Copyright (C) 2010 Intel Corporation.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __CLUTTER_PAINT_VOLUME_PRIVATE_H__
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#define __CLUTTER_PAINT_VOLUME_PRIVATE_H__
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#include <clutter/clutter-types.h>
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#include <clutter/clutter-private.h>
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G_BEGIN_DECLS
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struct _ClutterPaintVolume
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{
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/* A paint volume represents a volume in a given actors private
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* coordinate system. */
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ClutterActor *actor;
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/* cuboid for the volume:
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*
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* 4━━━━━━━┓5
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* ┏━━━━━━━━┓╱┃
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* ┃0 ┊7 1┃ ┃
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* ┃ ┄┄┄┄┄┃┄┃6
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* ┃3 2┃╱
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* ┗━━━━━━━━┛
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*
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* 0: top, left (origin) : always valid
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* 1: top, right : always valid
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* 2: bottom, right : updated lazily
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* 3: bottom, left : always valid
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*
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* 4: top, left, back : always valid
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* 5: top, right, back : updated lazily
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* 6: bottom, right, back : updated lazily
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* 7: bottom, left, back : updated lazily
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*
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* Elements 0, 1, 3 and 4 are filled in by the PaintVolume setters
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*
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* Note: the reason for this ordering is that we can simply ignore
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* elements 4, 5, 6 and 7 most of the time for 2D actors when
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* calculating the projected paint box.
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*/
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ClutterVertex vertices[8];
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/* As an optimization for internally managed PaintVolumes we allow
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* initializing ClutterPaintVolume variables allocated on the stack
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* so we can avoid hammering the slice allocator. */
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guint is_static:1;
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/* A newly initialized PaintVolume is considered empty as it is
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* degenerate on all three axis.
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*
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* We consider this carefully when we union an empty volume with
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* another so that the union simply results in a copy of the other
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* volume instead of also bounding the origin of the empty volume.
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*
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* For example this is a convenient property when calculating the
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* volume of a container as the union of the volume of its children
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* where the initial volume passed to the containers
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* ->get_paint_volume method will be empty. */
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guint is_empty:1;
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/* TRUE when we've updated the values we calculate lazily */
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guint is_complete:1;
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/* TRUE if vertices 4-7 can be ignored. (Only valid if complete is
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* TRUE) */
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guint is_2d:1;
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/* Set to TRUE initialy but cleared if the paint volume is
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* transfomed by a matrix. */
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guint is_axis_aligned:1;
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/* Note: There is a precedence to the above bitfields that should be
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* considered whenever we implement code that manipulates
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* PaintVolumes...
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*
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* Firstly if ->is_empty == TRUE then the values for ->is_complete
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* and ->is_2d are undefined, so you should typically check
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* ->is_empty as the first priority.
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*
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* XXX: document other invariables...
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*/
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};
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void _clutter_paint_volume_init_static (ClutterPaintVolume *pv,
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ClutterActor *actor);
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ClutterPaintVolume *_clutter_paint_volume_new (ClutterActor *actor);
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void _clutter_paint_volume_copy_static (const ClutterPaintVolume *src_pv,
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ClutterPaintVolume *dst_pv);
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void _clutter_paint_volume_set_from_volume (ClutterPaintVolume *pv,
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const ClutterPaintVolume *src);
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void _clutter_paint_volume_complete (ClutterPaintVolume *pv);
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void _clutter_paint_volume_transform (ClutterPaintVolume *pv,
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const CoglMatrix *matrix);
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void _clutter_paint_volume_project (ClutterPaintVolume *pv,
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const CoglMatrix *modelview,
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const CoglMatrix *projection,
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const float *viewport);
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void _clutter_paint_volume_get_bounding_box (ClutterPaintVolume *pv,
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ClutterActorBox *box);
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void _clutter_paint_volume_axis_align (ClutterPaintVolume *pv);
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void _clutter_paint_volume_set_reference_actor (ClutterPaintVolume *pv,
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ClutterActor *actor);
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ClutterCullResult _clutter_paint_volume_cull (ClutterPaintVolume *pv,
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const ClutterPlane *planes);
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void _clutter_paint_volume_get_stage_paint_box (ClutterPaintVolume *pv,
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ClutterStage *stage,
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ClutterActorBox *box);
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void _clutter_paint_volume_transform_relative (ClutterPaintVolume *pv,
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ClutterActor *relative_to_ancestor);
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G_END_DECLS
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#endif /* __CLUTTER_PAINT_VOLUME_PRIVATE_H__ */
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