This is cleaner than the if statements in the code. Also np2 textures
should in theory support linear filtering, but fglrx doesn't seem to
like it. This needs further investigation. So far we've never used
linear filtering on np2 textures, so there should not be a
regression. Furthermore I think shader support is more important than
filtering, since NP2 textures are mostly used for 1:1 copying to the
screen.
ATI cards prior to the radeon HD series did not have unconditional non
power of two support. So far we've used texture_rectangle for that, or
created a bigger power of two texture with padding. This had the
disadvantage that we had to correct the coordinates, which causes
extreme problems with shaders(doesn't work, pretty much).
Both the MacOS and the fglrx driver have support for
GL_ARB_texture_non_power_of_two, and run it on the hardware as long as
we stay within the texture_rectangle limitations. This allows us to
have conditional non power of two textures with normalized
coordinates. This patch adds an internal extension, and the code
creates a regular GL_TEXTURE_2D texture with NP2 size, but refuses
mipmapping, filtering and texture_rectangle incompatible
operations. This makes np2 textures work with shaders on fglrx and
macos.
This makes it easier to make this a per texture / per adapter property.
Somewhen we should rename the remaining lookup type in the general
lookup table to wraplookup.
Conditional NP2 textures in Direct3D do not support D3DTADDRESS_WRAP
texture addressing. Similarly, GL_ARB_texture_rectangle textures do
not support GL_REPEAT. This patch adds a test which shows that _WRAP
clamps to the texture edge and implements that.
relate to the opengl texture object will only be updated when they are
out of sync, this reduces the number of texture object state changes
during game play in Axis and allies from several hundreds to 0 or 1.
Stefan Dösinger