office-gobmx/slideshow
Noel Grandin 1c7cbd6856 use AlphaMask for variables when calling GetAlphaMask
Right now this doesn't make any difference, since Bitmap is the
superclass of AlphaMask.
But when I switch to using alpha instead of transparency, passing
AlphaMask around is going to mean something different to passing plain
Bitmap around.

Change-Id: Ic1541e5f0a3b97331793cd23e23115faa7f382b0
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/151463
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
2023-05-07 20:17:16 +02:00
..
inc/pch
opengl
qa
source use AlphaMask for variables when calling GetAlphaMask 2023-05-07 20:17:16 +02:00
test
util
CppunitTest_slideshow.mk
CppunitTest_slideshow_engine.mk
IwyuFilter_slideshow.yaml
Library_OGLTrans.mk
Library_slideshow.mk
Makefile
manifest.txt
Module_slideshow.mk
Package_opengl.mk
README.md

Impress Slideshow Engine

3D Transitions

The 3D transitions are slideshow transition engine using OpenGL and are located in slideshow/source/engine/OGLTrans/. They were initially written by GSOC student Shane.M.Mathews. Radek has later polished the code a bit, added few new 3D transitions, added infrastructure for vertex and fragment shaders. Wrote few transitions with fragment shader too.

Physics Animation Effects

Physics animation effects are simulated by external 2d physics engine library Box2D. They don't directly call Box2D functions but instead use the wrapper in:

  • slideshow/source/inc/box2dtools.hxx
  • slideshow/source/engine/box2dtools.cxx

The wrapper has two corresponding classes to manage the Box2D world and Box2D bodies.

When a physics animation starts, a Box2DWorld is initiated and populated with every shape that is part of the foreground (which are shapes that do not belong to the master slide and not a background shape).

After creation until the end of the slide (not the whole slideshow) the Box2D World isn't destroyed and reused. But the bodies that represent the shapes in the slide get destroyed when there's a point in time that there's no physics animation in progress. And recreated when another physics animation starts.

If there are multiple physics animations in parallel only one of them takes the role of stepping through the simulation.

If there are other animation effects that go in parallel which change the shape position, rotation, or visibility - they also report the change to Box2DWorld. These updates are collected in a queue in Box2DWorld and processed before stepping through the simulation. To achieve convincing results these updates are performed by setting the Box2D body's linear velocity or angular velocity instead of setting directly it's position or rotation.