Commit Graph

4 Commits

Author SHA1 Message Date
Neil Roberts
45215cb426 cogl-atlas-texture: Fix a cut and paste error when getting the height
There was a typo in getting the height of the full texture to check
whether the sub region fits so that it was using the width
instead. This was causing crashes when debugging is enabled for some
apps.
2010-02-05 17:03:04 +00:00
Neil Roberts
ae7825275e cogl: Make CoglSubTexture only work for quad rendering
The sub texture backend doesn't work well as a completely general
texture backend because for example when rendering with cogl_polygon
it needs to be able to tranform arbitrary texture coordinates without
reference to the other coordintes. This can't be done when the texture
coordinates are a multiple of one because sometimes the coordinate
should represent the left or top edge and sometimes it should
represent the bottom or top edge. For example if the s coordinates are
0 and 1 then 1 represents the right edge but if they are 1 and 2 then
1 represents the left edge.

Instead the sub-textures are now documented not to support coordinates
outside the range [0,1]. The coordinates for the sub-region are now
represented as integers as this helps avoid rounding issues. The
region can no longer be a super-region of the texture as this
simplifies the code quite a lot.

There are two new texture virtual functions:

transform_quad_coords_to_gl - This transforms two pairs of coordinates
     representing a quad. It will return FALSE if the coordinates can
     not be transformed. The sub texture backend uses this to detect
     coordinates that require repeating which causes cogl-primitives
     to use manual repeating.

ensure_non_quad_rendering - This is used in cogl_polygon and
     cogl_vertex_buffer to inform the texture backend that
     transform_quad_to_gl is going to be used. The atlas backend
     migrates the texture out of the atlas when it hits this.
2010-01-18 09:22:04 +00:00
Neil Roberts
63c984f193 cogl-sub-texture: Fix the height of sub textures
The code which is used to get the texture height was accidentally
using the width due to a cut-and-paste fail.
2009-12-03 14:46:20 +00:00
Neil Roberts
c9cafc798c cogl: Add a sub texture backend
This adds a new texture backend which represents a sub texture of a
larger texture. The texture is created with a reference to the full
texture and a set of coordinates describing the region. The backend
simply defers to the full texture for all operations and maps the
coordinates to the other range. You can also use coordinates outside
the range [0,1] to create a repeated version of the full texture.

A new public API function called cogl_texture_new_from_sub_texture is
available to create the sub texture.
2009-12-02 22:03:08 +00:00