gistfile1.cpp

	u32 readWrappedTexel(CubeFace face, int x, int y) {
		assert(face < NUM_FACES);

		static const CubeFace face_left_of[] = {
			/* FACE_POS_X */ FACE_POS_Z,
			/* FACE_NEG_X */ FACE_NEG_Z,
			/* FACE_POS_Y */ FACE_NEG_X,
			/* FACE_NEG_Y */ FACE_NEG_X,
			/* FACE_POS_Z */ FACE_NEG_X,
			/* FACE_NEG_Z */ FACE_POS_X
		};

		static const CubeFace face_right_of[] = {
			/* FACE_POS_X */ FACE_NEG_Z,
			/* FACE_NEG_X */ FACE_POS_Z,
			/* FACE_POS_Y */ FACE_POS_X,
			/* FACE_NEG_Y */ FACE_POS_X,
			/* FACE_POS_Z */ FACE_POS_X,
			/* FACE_NEG_Z */ FACE_NEG_X
		};

		static const CubeFace face_above[] = {
			/* FACE_POS_X */ FACE_POS_Y,
			/* FACE_NEG_X */ FACE_POS_Y,
			/* FACE_POS_Y */ FACE_NEG_Z,
			/* FACE_NEG_Y */ FACE_POS_Z,
			/* FACE_POS_Z */ FACE_POS_Y,
			/* FACE_NEG_Z */ FACE_POS_Y
		};

		static const CubeFace face_under[] = {
			/* FACE_POS_X */ FACE_NEG_Y,
			/* FACE_NEG_X */ FACE_NEG_Y,
			/* FACE_POS_Y */ FACE_POS_Z,
			/* FACE_NEG_Y */ FACE_NEG_Z,
			/* FACE_POS_Z */ FACE_NEG_Y,
			/* FACE_NEG_Z */ FACE_NEG_Y
		};

		while (true) {
			if (x < 0) {
				CubeFace new_face = face_left_of[face];
				if (face == FACE_POS_Y) {
					int new_y = -x - 1;
					x = y;
					y = new_y;
				} else if (face == FACE_NEG_Y) {
					int new_x = faces[new_face].width - y - 1;
					int new_y = faces[new_face].height + x;
					x = new_x;
					y = new_y;
				} else {
					x = faces[new_face].width + x;
				}

				face = new_face;
			} else if (x >= faces[face].width) {
				CubeFace new_face = face_right_of[face];
				if (face == FACE_POS_Y) {
					int new_x = faces[new_face].width - y - 1;
					int new_y = x - faces[face].width;
					x = new_x;
					y = new_y;
				} else if (face == FACE_NEG_Y) {
					int new_y = faces[new_face].height - (x - faces[face].width) - 1;
					x = y;
					y = new_y;
				} else {
					x = x - faces[face].width;
				}

				face = new_face;
			} else if (y < 0) {
				CubeFace new_face = face_above[face];
				if (false) {
					// ...
				} else {
					y = faces[new_face].height + y;
				}
			} else if (y >= faces[face].height) {
				// ...
			} else {
				break;
			}
		}
	}