When using pbuffer or back buffer offscreen rendering the content of
the drawable will have been overwritten. Thus the texture has to be
written into the drawable. An exception is the (pretty common) case
that the whole render target is cleared before rendering to it.
The state handler binds index buffer 0 when a user pointer is used. Likewise the real index
buffer has to be restored when switching back to drawing from index buffers.
Previously the surfaces stored a flag if the system memory copy was
ahead of the gl copy(SFLAG_DIRTY) or the gl copy is
ahead(SFLAG_GLDIRTY). The pbuffer copy was 'managed' differently using
SFLAG_INPBUFFER and SFLAG_INTEXTURE.
This patch replaces them with 3 flags, INSYSMEM, INPBUFFER and
INTEXTURE which specify which copy contains the most up to date
copy. It is perfectly valid to have more than one of those flags
set. One must be set at least (except at init, when no content is in
the surface yet). When one copy is modified, the flags for the others
are removed.
The method is removed because it does not really help with
anything. It should not be exported from wined3d, there is no need for
the other libs to call it. It does not help abstraction and code
simplification in any way because it is very specific and the code
calling it has to know what is happening in the surface to use this
method.
The gl viewport origin is the lower left corner of the window, in d3d
it is the upper right corner. This is corrected when setting the
viewport. However, when we are doing offscreen rendering, this is
reversed. So do not flip the viewport origin when rendering offscreen.
Except with fbos, it is not possible to remove the depth stencil
buffer from the opengl frame buffer, so when the d3d app sets a NULL
depth stencil disable all states that work with the depth stencil
buffer.
This helps performance a bit because the function does not have to
wait for the 2nd read to finish before returning. Only do that if we
have an aux buffer to mess with for free though.
Plain OpenGL does not provide any signed pixel formats, so the
unsigned GL_RGB is used for loading perturbation data into pixel
shaders that use texbem. For correct loading, the signedness has to be
considered.
When drawing processed vertices with the fixed function pipeline the
projection matrix is set up to map y values from 0 to height to 1.0;
-1.0(gl and d3d coord systems are flipped). This moves the y axis to
the bottom of the drawing area. When later on the y inversion matrix
is applied for offscreen rendering, the coordinate system will get
flipped out of the viewport.
This patch sets the Y range up upside down when using offscreen
rendering, so the invymat will flip it to the correct position. This
has to happen before the 0.375 pixel correction.
It was incorrect to disable the scissor test for full surfaces in my
clear patch. With back buffer offscreen rendering the viewport does
not seem to restrict clearing, and with different sizes of depth
stencil and color buffer the final fantasy XI demo seems to expect the
clear to be restricted.
The hwstretch blit code creates a new texture each time it is called
to back up the back buffer and releases it afterwards. It is more
efficient to keep the texture and release it with the surface.
OpenGL AUX buffers provide a way for offscreen rendering which is very
similar to our back buffer "offscreen" rendering emulation. Not all
card support aux buffers, but if they are available they are a nice
present which is easy to use.
Stefan Dösinger