So i have a game engine core written in c99 and i would love to use nim to make
it full-blown game engine. I have a struct which contains const fields, and it
works fine with pure c.
// Don't mind the type names, those are configured in somewhere else in the
project
typedef struct kira_renderer_batcher {
const u32 max_objects;
const u32 max_index, max_vertex;
u32 vertex_array, vertex_buffers[2]; // vao, vbo, ebo
u32 submission_counter;
kira_renderer_vertex* vertex_list;
u32* index_list;
} kira_renderer_batcher;
int main() {
static kira_renderer_batcher batch = (kira_renderer_batcher) {
1024, 6, 4, 0, {0, 0}, 0, (kira_renderer_vertex*)null, (u32*)null
};
}
Run
I tried to use this struct in nim, but i could not find solution for assign
data into constant fields. I am not sure this is going to work the way i am
doing this
type batcher* {.header: "KIRA/renderer/batcher.h", importc:
"kira_renderer_batcher", bycopy.}
= object
max_objects*, max_index*, max_vertex*: uint32
vertex_array*: uint32
vertex_buffers*: array[2, uint32]
submission_counter*: uint32
vertex_list*: ptr vertex
index_list*: ptr uint32
# This does not work
var batch: batcher = batcher(max_objects: 1024, max_index: 6,
max_vertex: 4)
Run
The compile error(From what i understanding it tries assign values one by one
instead of just do the all in once like i did):
/home/kira/.cache/nim/main_d/@mmain.nim.c: In function
‘main__QR2FCf1rO4331t6VVp9auAA’:
/home/kira/.cache/nim/main_d/@mmain.nim.c:321:24: error: assignment of
read-only member ‘max_objects’
321 | batch.max_objects = ((NU32) 1024);
| ^
/home/kira/.cache/nim/main_d/@mmain.nim.c:322:22: error: assignment of
read-only member ‘max_index’
322 | batch.max_index = ((NU32) 6);
| ^
/home/kira/.cache/nim/main_d/@mmain.nim.c:323:23: error: assignment of
read-only member ‘max_vertex’
323 | batch.max_vertex = ((NU32) 4);
| ^
Run
How am i going to do this without having to remove the constant signature from
the struct?? (Well i actually in theory i just need to remove macro from the
nim object and it should do the job but i want to have the safety of constants)
