The GTK and OS X platforms already ignored the requested bit depth and
always used 32 bit. Windows and SDL would set a 16 bit color depth for
the screen, but still did all of the rendering short of the final
present in 32 bit.
Unlike GLX, the OpenGL function pointers are context-dependant. Because we
need an extension function to create the context we're going to use, we
first need to create a temporary context. Since this is independent of the
library used to fetch the function pointers, decouple it from glewInit().
USE_WIN32_WINDOWS was previously defined in PlatformAbstraction.h. Move it
to CMakeLists.txt and config.h like its peers. Replace USE_X11 with USE_GTK
or GDK_WINDOWING_X11 as appropriate.
Basically add another layer of indirection around accessing VAOs. The problem
is that VAOs are not shared between OpenGL contexts. This mechanism allows to
treat them mostly as if they were shared if they are only accessed through
the API defined in CStdGL.
This is accomplished by caching all existing VAOs per context. If a VAO is
being accessed, it is checked whether that VAO exists in the currently
selected context. If yes, return it, otherwise create a new VAO and return it,
together with a flag that indicates that the VAO needs to be initialized.
I don't expect much of a performance benefit from this, but it works toward
removal of legacy OpenGL usage. Note that we are already using VBOs for
meshes, so this does not require any functionality that we don't require
already.
Replace the hardcoded VAI_ constants with that. The VAI constants are now
moved to C4DrawGL as C4SSA_ constants, similar to the C4SSU ones. This allows
to introduce other attributes to replace vertex positions, normals, colors
and texture coordinates with attributes in later commits. This, in turn, is
needed because the built-in attributes are no longer available in the OpenGL
core profile.
Also, while at it, cleanup C4Shader a bit. Use std::vector<> instead of
maintaining an own array of uniform names. Delete the vertex and fragment
objects after the full shader program has been linked. Make sure that
C4Shader::Init keeps the old program in place if the new one cannot be
compiled or linked.
In a surprising touch, using shaders to affect pretty much every pixel
that gets drawn on screen means there is little reason for code to ask
the renderer if it knows about shaders.
There are only a couple of error values worth considering, so we can just
write out own function for it. Disable error checking in C4FoWRegion.cpp as
well, since we have the --debug-opengl flag now.
This should allow us to get rid of the GLU dependency soon.
Instead, compute the projection, modelview and normal matrices explictly
and upload them as shader uniforms. This is one step towards using the
OpenGL 3 core profile.
Add a C4ShaderCall parameter to tho most important drawing functions, and
make C4DrawGL's CreateSpriteShader public with additional parameters to
specify additional defines and shader slices. C4Sky uses this to compile its
own shader with OC_SKY defined.
In comparison to the old system, this is a downgrade - instead of being
able to set a full color mapping by gamma ramp, we now get just a value
per colour channel.
Upside is that we do not need to play around with the global gamma ramps
any more, which was arguably the wrong way to do it.
This commit will likely break everything that has been using gamma so far.
Some resources can't be shared across different rendering contexts while
others can. Additionally, the standard GLEW library does not support
multiple rendering contexts (that's what GLEX MX is for), even though it
might work on some (or even most) cards. WGL supports reuse of a
rendering context across multiple windows as long as the pixel formats
are the same.
4x3 matrices use the same number of uniform components as 4x4 ones.
If we're short on uniform components, don't transpose the transformation
matrix before sending it to the shader, and transpose it in the shader
itself instead, saving 4 components per bone.
Instead of transforming all vertices on the CPU every time an animation
progresses, we now only recalculate the skeleton, leaving the heavy
lifting for the GPU. This also means we no longer have to push all
vertices onto the bus every frame, because the mesh isn't changing and
can therefore be stored in a GL_STATIC_DRAW VBO when it's first loaded.
The downside of this approach is that there's only a limited number of
uniforms and vertex attributes we can pass to the shader. At the moment
these limits are a maximum of 128 bones per skeleton, and no vertex can
be influenced by more than 8 bones at once. So far this is no problem,
as the most complex skeleton in the base game uses less than 64 bones
and no more than 6 bone weights per vertex.
gluErrorString returns latin-1 encoded strings. Our code expects to
receive UTF-8 encoded strings everywhere, so make sure that the strings
are converted before passing them on.
This code is only used for the low-resolution landscape that is hardly in use
anymore. The code was mostly a duplicate of the standard C4Surface blit
function, CStdGL::PerformBlt, with some added code for blitting material
textures with higher resolution. However, that code was not enabled anymore
by the classic landscape renderer either, so it seems safe to remove it.
The landscape is now simply drawn by C4Draw::Blit.
Nicolas Hake