add vibecoded artnet lib

draw_parra/artnet_receiver.h

@@ -0,0 +1,41 @@
+/* --------------------------------------------------------------------
+ *  artnet_receiver.c  – tiny Art‑Net DMX receiver
+ *
+ *  This file contains only the pieces you need to:
+ *      * open a UDP socket on port 6454,
+ *      * receive ArtDMX packets,
+ *      * extract the DMX data (up to 512 bytes),
+ *      * copy the first N bytes into the variables of the main program.
+ *
+ *  The code is deliberately simple – it ignores ArtPoll, ArtSync,
+ *  multiple universes, etc.  If you need those features you can replace
+ *  the receive loop with libartnet or another full implementation.
+ * -------------------------------------------------------------------- */
+
+#ifndef ARTNET_RECEIVER_H
+#define ARTNET_RECEIVER_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <pthread.h>
+
+/* ---------------------------------------------------------------
+ *  Public API – call from the main program
+ *
+ *  artnet_init()   : creates the receiving thread.
+ *  artnet_stop()   : asks the thread to terminate and joins it.
+ * --------------------------------------------------------------- */
+bool artnet_init(void);          /* returns true on success   */
+void artnet_stop(void);
+
+/* ---------------------------------------------------------------
+ *  The variables that the Art‑Net thread will write to.
+ *  They are declared `extern` here and defined in the main file.
+ * --------------------------------------------------------------- */
+extern int16_t  rotAnglesDeg[12];   /* 0 … 180°   (mapped from 0‑255) */
+extern int      LINE_THICKNESS;    /* 1 … 10    (clamped)            */
+extern int      MARGIN_TOP;        /* 0 … 200 px (scaled)            */
+extern int      MARGIN_BOTTOM;     /* 0 … 200 px (scaled)            */
+
+#endif /* ARTNET_RECEIVER_H */