backport cont.

[dosdemo] / src / 3dgfx / polyclip.h

diff --git a/src/3dgfx/polyclip.h b/src/3dgfx/polyclip.h
new file mode 100644 (file)
index 0000000..adee29d
--- /dev/null
+++ b/src/3dgfx/polyclip.h
@@ -0,0 +1,38 @@
+#ifndef POLYCLIP_H_
+#define POLYCLIP_H_
+
+#include "3dgfx.h"
+
+struct cplane {
+       float x, y, z;
+       float nx, ny, nz;
+};
+
+enum {
+       CLIP_LEFT, CLIP_RIGHT,
+       CLIP_BOTTOM, CLIP_TOP,
+       CLIP_NEAR, CLIP_FAR
+};
+
+/* Generic polygon clipper
+ * returns:
+ *  1 -> fully inside, not clipped
+ *  0 -> straddling the plane and clipped
+ * -1 -> fully outside, not clipped
+ * in all cases, vertices are copied to vout, and the vertex count is written
+ * to wherever voutnum is pointing
+ */
+int clip_poly(struct g3d_vertex *vout, int *voutnum,
+               const struct g3d_vertex *vin, int vnum, struct cplane *plane);
+
+/* only checks if the polygon would be clipped by the plane, and classifies it
+ * as inside/outside/straddling, without actually producing a clipped polygon.
+ * return values are the same as clip_poly.
+ */
+int check_clip_poly(const struct g3d_vertex *v, int vnum, struct cplane *plane);
+
+/* Special-case frustum clipper (might be slightly faster) */
+int clip_frustum(struct g3d_vertex *vout, int *voutnum,
+               const struct g3d_vertex *vin, int vnum, int fplane);
+
+#endif /* POLYCLIP_H_ */