Currently the user had to ensure that buffers added to mesh were not
moved at all, which was very annoying, basically each one of them had to
be allocated on heap. Now the Mesh stores a weak copy (yes, really) using
Buffer::wrap() with no deletion on destruction, so the original instance
can be freely moved around without any fear of crash.
Thanks to @Squareys for the original idea/request about wrap() functions,
really useful part of the API.
Similarly to what's now done with NoInit tags for Containers::Array and
all math types such as Vector, there's now NoCreate tag for creating
wrappers without actually creating the underlying OpenGL object. The
instance is then equivalent to moved-from state. Useful to avoid
needless creation/deletion of OpenGL object in case you would overwrite
the instance later anyway:
Mesh mesh{NoCreate};
std::unique_ptr<Buffer> indices, vertices;
std::tie(mesh, indices, vertices) = MeshTools:compile(...);
The original goal was to avoid branches when binding the vertex
attributes for drawing, so I stored float, integral and double
attributes in separate std::vector instances and then was going through
each one of them in separate loop. In retrospect that was _not_ a good
idea, because it results in larger Mesh class, two more allocations
resulting in far more pointer chasing and more complicated
constructor/destructor.
Now everything is stored in a single vector. I may optimize it further
by not calling the constructor/destructor on it when VAOs are used.
Actually properly supporting ANGLE_instanced_arrays. Emscripten
currently has the functions without the ANGLE suffix. Only causes linker
warnings when not used, need to fill a bugreport and fix properly.
It is not related to Mesh itself at all, as the attribute indices are
defined in Attribute class. Use
AbstractShaderProgram::maxVertexAttributes() instead.
This function was added to ARB_instanced_arrays spec very late and thus
some implementations don't provide it (one case being AMD drivers on
Linux). If that function is not available, the non-DSA VAO specification
is used instead.
No backward compatibility issues should exist, as the class is in most
(if not all) cases used with unscoped name:
class MyShader: public AbstractShaderProgram {
public:
typedef Attribute<0, Vector3> Position;
// ...
};
In most cases the label is set directly from code, e.g.:
texture.setLabel("diffuse-duck");
Avoiding conversion to std::string and passing char(&)[size] directly
will avoid one allocation and deallocation. Better solution would be to
use std::string_view everywhere, but we're not in C++17 yet.
In OpenGL ES this is implemented in EXT_multi_draw_arrays extension, if
it is not available, the functionality is emulated using sequence of
normal draw() calls.
Functionality provided by GL 3.3 and ARB_instanced_arrays, on ES2 this
is again implemented in three different extensions --
{ANGLE,EXT,NV}_instanced_arrays. They are disabled until Magnum has
proper extension loading on ES.
On desktop GL this is provided by ARB_draw_instanced (GL 3.1). Base
instance is available only on desktop GL (4.2, ARB_base_instance). In
ES2 the instanced functionality is provided by three (!) different
extensions (ANGLE_instanced_arrays, EXT_draw_instanced,
NV_draw_instanced), the proper implementation is chosen on context
creation based on what extension is available. Though we don't have
extension loader for ES yet, thus all these extensions are disabled and
the implementation has assertion in it.
Added blind test which tests only that something has been drawn and no
errors were emitted, but not whether the right command is used. I'll
probably need to check this later, because the Mesh::draw() behemoth is
going slightly out of hand :)
The point of this change is to allow greater flexibility and reduce
confusion.
When instanced meshes are implemented, MeshTools::interleave() can be
used for creating interleaved buffers with per-instance data and then
the call to Mesh::setCount() will be harmful and/or confusing, becuase
the user would in fact want to call Mesh::setInstanceCount() instead.
Similarly, MeshTools::compressIndices() can be used to create index
buffer for more than one mesh.
GL 4.4 has ARB_buffer_storage, which (in relatively distant future) will
mean that the current way of Buffer::setData() will be deprecated in
favor of Buffer::setStorage(), similarly as Texture::setStorage()
replaced Texture::setImage(). Thus any function which calls
Buffer::setData() internally is not future-proof.
The old MeshTools::compressIndices() and MeshTools::interleave()
overloads are marked as deprecated and will be removed in future
release.
The well-known issue is that gl*DrawElements*BaseVertex() is not
supported in OpenGL ES. It is possible to work around it by
reconfiguring whole VAO, but that seems to be a bit overkill. Currently
the draw() function just asserts that base vertex is not specified for
indexed meshes.
Only one value from these two was used in the end, wasting precious
bytes. Also these two values were used to differentiate between indexed
and non-indexed mesh (instead of relying on actual index buffer being
bound), which was very confusing. This approach looks more clean. The
MeshView class is not yet updated, as the change would expose some
features that aren't possible in current implementation (base vertex
specification).
Merged Mesh::setVertexCount() and Mesh::setIndexCount() into one
Mesh::setCount(), the two original functions are now guarded aliases to
the new one, are marked as deprecated and will be removed in future
release, similarly for the getters.
In particular, if the mesh is indexed, setVertexCount() does nothing and
vertexCount() returns 0. The setIndexCount() and indexCount() do and
return the same regardless of whether the mesh is indexed or not.
In all other places (e.g. Math, SceneGraph), SomeClass<T>::Type is
always T. I spent twenty minutes figuring out what went wrong, so better
have this consistent.
Also update the test to check for these, as they apparently were tested
only indirectly through the MeshGLTest.
Previously the API didn't encourage the user to set up and activate
shader before drawing the meshes, leading to unintuitive behavior:
// Can I just call draw() or do I have to fully understand the
// meaning of the universe before?
mesh.draw();
Now the draw() needs the shader passed explicitly as parameter, which
should hint that the shader must be set up somehow:
// Right, so this needs just a shader and that's all. Expecting this
// I fortunately *did* configure all the uniforms before this call.
mesh.draw(shader);
It is also possible to pass the shader as rvalue, in case the drawing is
just a one-off thing and is already fully configured.
mesh.draw(MyShader{});
As usual, the original API is kept, is marked as deprecated and will be
removed in some future release.
Vladimír Vondruš