Hi, I'm trying to create a spine runtime for rayblib (https://www.raylib.com/)

For that, I'm using the generic C libraries version 3.8 (https://github.com/EsotericSoftware/spine-runtimes/tree/3.8/spine-c)

Everything goes well except for 2 things:

1. The animation is upside down.
2. Any scale < 0 make the animation disappear.

The most important thing to solve for me is 1, but maybe this two problems are related.

My code is here:
https://github.com/WEREMSOFT/flecs_plus_raylib/tree/raylib-example

The meaningful code is here:

https://github.com/WEREMSOFT/flecs_plus_raylib/blob/raylib-example/src/spine/extension.c
in the function

engine_drawMesh

this is the meaningful code where I think is the problem:

void draw_vertex(Vertex vertex, Vector3 position){
    rlTexCoord2f(vertex.u, vertex.v);
    rlColor4f(vertex.r, vertex.g, vertex.b, vertex.a);
    rlVertex3f( position.x + vertex.x, position.y + vertex.y, position.z);
}

void engine_drawMesh(Vertex* vertices, int numVertices, Texture* texture, Vector3 position){
    Vertex vertex;

rlEnableTexture(texture->id);

rlPushMatrix();
{
    rlBegin(RL_QUADS);
    {
        rlNormal3f(0.0f, 0.0f, 1.0f);
        for (int i = 0; i < numVertices; i++){
            if(i < 3 || i == 4){
                vertex = vertices[i];
                draw_vertex(vertex, position);
            }
        }
    }rlEnd();
}rlPopMatrix();
rlDisableTexture();
}

What I've already tried:
Invert the normal when doing scaleY = -1 on the skeleton
Draw Vertices in inverse orden when scaleY = -1 on the skeleton

This is how it looks when loading the skeleton without any scale

This is how it looks with a scaleY of 0.25

This is how it looks with a scaleY -1

I have same results when I scale on X axis.

Thanks in advance

Thanks @badlogic. It's not upside down anymore, but I have to flip it vertically in order to see the render.

spBone_setYDown(true);
skeleton = spSkeleton_create(skeletonData);
skeleton->scaleX = -0.5; // Now I have to do this!
skeleton->scaleY = 0.5;

I'm having this problem flicking the model and I don't understand why. It's about the backface culling for sure.

Do you have any idea about what else can I try to solve this flicking problem?

This is what I have (the model is looking in the wrong direction)

Ok, I have to disable the backface culling but this is a performance hit! I need to check if it's possible to disable backface culling only for the spine model.

rlDisableBackfaceCulling(); // Disables the backface culling for the whole game!!!