+/*
+ * TEXTURING
+ * If enabled, a texture will be used to color models that have texture
+ * coordinates. The color from the texture will actually be multiplied
+ * (i.e. mixed) with the regular color associated with the geometry. Also,
+ * Phong interpolation lighting (LIGHTING >= 3) is required to get actual
+ * texturing; otherwise, only the color at the origin point of the texture
+ * will be used.
+ */
+#if TEXTURING
+#define IF_TEXTURING(X) X
+#else
+#define IF_TEXTURING(X)
+#endif
+
+/*
+ * PERSPECTIVE_FIX
+ * If enabled, texturing will have correct perspective on triangles which
+ * show depth. You typically always want this, so it's enabled by default.
+ * This option is useful only if TEXTURING is also enabled.
+ */
+#ifndef PERSPECTIVE_FIX
+#define PERSPECTIVE_FIX 1
+#endif
+#if PERSPECTIVE_FIX
+#define IF_PERSPECTIVE_FIX(X) X
+#else
+#define IF_PERSPECTIVE_FIX(X)
+#endif
+