Callable from Python inside Rust

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2

Maybe this helps:

I tested it successfully but without rust-cython.

My way is creating a "cdylib" Target from Rust

Rust:

#[no_mangle]
pub extern fn noise_texture_ds_middlefunc() -> fn(x1: f32, x2: f32, x3: f32, x4: f32) -> f32 {
	middle_quad
}

#[no_mangle]
pub extern fn noise_texture_ds(width: i32, height: i32, maxred: f32, red: f32, startseed: f32,
							   middlefunc: fn(x1: f32, x2: f32, x3: f32, x4: f32) -> f32)
 -> *mut u8 {
...
}

pythonlib.py:

lib = ctypes.cdll.LoadLibrary("py_render_lib.dll")

lib.noise_texture_ds.args = (c_int, c_int, c_float, c_float, c_float,)
lib.noise_texture_ds.restype = POINTER(c_ubyte)

lib.noise_texture_ds_middlefunc.restype = POINTER(CFUNCTYPE(c_float,c_float,c_float,c_float))

@CFUNCTYPE(c_float,c_float,c_float,c_float,c_float)
def pymiddle(x1, x2, x3, x4):
	return (x1 + x2 + x3 + x4) / 2.5

def run_test():
	print("start noise test")
	w = 513
	#middlefunc = lib.noise_texture_ds_middlefunc()
	middlefunc = pymiddle
	result = lib.noise_texture_ds(c_int(w), c_int(w), c_float(1.0), c_float(0.5), c_float(1.0), middlefunc)
        .....

As you can see that works without any extra crate too.