Function sam3_bbox_mlp

sam3.cpp:8184–8194

Box refinement MLP (3 layers: D→D→D→4 with ReLU)

// Box refinement MLP (3 layers: D→D→D→4 with ReLU)
static struct ggml_tensor* sam3_bbox_mlp(struct ggml_context* ctx,
                                         struct ggml_tensor* x,
                                         struct ggml_tensor* w[3],
                                         struct ggml_tensor* b[3]) {
    for (int j = 0; j < 3; ++j) {
        x = ggml_mul_mat(ctx, w[j], x);
        x = ggml_add(ctx, x, b[j]);
        if (j < 2) x = ggml_relu(ctx, x);
    }
    return x;
}

// Build sinusoidal positional embedding for 4D reference points in the ggml graph.
// ref_boxes: [4, NQ, B] — (cx, cy, w, h) after sigmoid, B=1