python: expose gl.Framebuffer.attach_texture().

Co-authored-by: Vladimír Vondruš <mosra@centrum.cz>

src/python/magnum/gl.cpp

@@ -911,6 +911,13 @@ void gl(py::module_& m) {
                before the framebuffer */
             pyObjectHolderFor<GL::PyFramebufferHolder>(self).attachments.emplace_back(pyObjectFromInstance(renderbuffer));
         }, "Attach renderbuffer to given buffer", py::arg("attachment"), py::arg("renderbuffer"))
+        .def("attach_texture", [](GL::Framebuffer& self, GL::Framebuffer::BufferAttachment attachment, GL::Texture2D& texture, Int level) {
+            self.attachTexture(attachment, texture, level);
+
+            /* Keep a reference to the texture to avoid it being deleted before
+               the framebuffer */
+            pyObjectHolderFor<GL::PyFramebufferHolder>(self).attachments.emplace_back(pyObjectFromInstance(texture));
+        }, "Attach texture to given buffer", py::arg("attachment"), py::arg("texture"), py::arg("level"))
 
         .def_property_readonly("attachments", [](GL::Framebuffer& self) {
             return pyObjectHolderFor<GL::PyFramebufferHolder>(self).attachments;

src/python/magnum/test/test_gl_gl.py

@@ -180,6 +180,20 @@ class Framebuffer(GLTestCase):
         del framebuffer
         self.assertEqual(sys.getrefcount(renderbuffer), renderbuffer_refcount)
 
+    def test_attach_texture(self):
+        texture = gl.Texture2D()
+        texture.set_storage(levels=1, internal_format=gl.TextureFormat.RGBA8, size=(4, 4))
+        texture_refcount = sys.getrefcount(texture)
+
+        framebuffer = gl.Framebuffer(((0, 0), (4, 4)))
+        framebuffer.attach_texture(gl.Framebuffer.ColorAttachment(0), texture, 0)
+        self.assertEqual(len(framebuffer.attachments), 1)
+        self.assertIs(framebuffer.attachments[0], texture)
+        self.assertEqual(sys.getrefcount(texture), texture_refcount + 1)
+
+        del framebuffer
+        self.assertEqual(sys.getrefcount(texture), texture_refcount)
+
     def test_read_image(self):
         renderbuffer = gl.Renderbuffer()
         renderbuffer.set_storage(gl.RenderbufferFormat.RGBA8, (4, 4))