glFrameBufferTexture maps to all faces of a cube and that is not needed
here. Additionally, texture_id is not deleted after we use the additional
flipped texture, but should be.
On desktop GL, GL 1.5 or GL_ARB_occlusion_query is required to get the
glGenQueries() etc. symbols. This isn’t the case on GLES, where they
are provided by GL_EXT_occlusion_query_boolean, and more importantly
have never been made core.
This patch allows gtk4-demo to start when GDK_DEBUG=gl-gles is set, on
my Mali 400 MP running the Lima driver from Mesa.
We're caching two things, either a node itself being rendered, or a
parent storing a cached version of a child as rendered to an offscreen
the size and location of the parent.
If both the parent and child uses the cache this will cause a conflict in
the cache as it is currently use keying of a node pointer which will have
the same value for the node-as-itself and the child-node-of-the-parent.
We fix this by adding another part to the key "pointer_is_child" which means
we can have the same node pointer twice in the cache.
Additionally, in the child-is-rendered-offscreen case the offscreen
result actually depends on the position and size of the parent viewport,
so we need to store the parent bounds in that case.
This allows us to avoid updating uniforms if that is not necessary. This
in turn allows us to sometimes reuse the same draw op by just extending the
vertex array size we draw rather than doing a separate glDraw call.
For example, in the fishbowl demo, all the icons added at the same
time will have the same time and size, so we emit single draw calls
with 100s of triangles instead of 100s of draw calls with 2 triangles.
For vulkan/broadway this just means to ignore it, but for the gl
backend we support (with up to 4 texture inputs, which is similar to
what shadertoy does, so should be widely supported).
Print out the full assembled shader sources when
GSK_DEBUG=shaders is given. This is very verbose,
but may be useful to see what we actually pass
to the compiler.
Almost always the source is created by combining various sources, which
means the line numbers in the error messages are hard to use. Adding
the line numbers to the source in the error message helps with this.
There is no real reason to have this on the side indexed via the
index, as it is stored next to each other anyway. Plus, storing them
together lets use use `Program` structures not in the array.
I found that the gears demo was spending 40% cpu
downloading a GL texture every frame, only to
upload it again to another context.
While the GSK rendering and the GtkGLArea use different
GL contexts, they are (usually) connected by sharing data
with the same global context, so we can just use the
texture without the download/upload dance. This brings
gears down to < 10% cpu.
Do custom uploads rather than using gdk_cairo_surface_upload_to_gl(),
because this way we avoids a roundtrip (memcpy and possibly conversion)
to the cairo image surface format.
GLES doesn't support the GL_BGRA + GL_UNSIGNED_INT_24_8 hack that
we use on desktop OpenGL to upload textures directly in the cairo
pixel format. This adds the required conversions to all the places
that currently need it.
We also add a data_format to the internal gdk_gl_context_upload_texture()
function to make it clearer what the format are. Currently it is always
the cairo image surface format, but eventually we want to support other
formats so that we can avoid some of the unnecessary conversions we do.
Also, the current gdk_gl_context_upload_texture() code always converts
to a cairo format and uploads that like we did before. Later commits
will allow this to use other upload formats that gl supports to avoid
conversions.
