1 /* vector.h: operations on vectors and points. */ 2 3 #ifndef VECTOR_H 4 #define VECTOR_H 5 6 #include "types.h" 7 #include "exception.h" 8 9 /* Our vectors are represented as displacements along the x and y axes. */ 10 11 typedef struct { 12 gfloat dx, dy, dz; 13 } vector_type; 14 15 /* Consider a point as a vector from the origin. */ 16 extern vector_type make_vector(const at_real_coord); 17 18 /* And a vector as a point, i.e., a displacement from the origin. */ 19 extern at_real_coord vector_to_point(const vector_type); 20 21 /* Definitions for these common operations can be found in any decent 22 linear algebra book, and most calculus books. */ 23 24 extern gfloat magnitude(const vector_type); 25 extern vector_type normalize(const vector_type); 26 27 extern vector_type Vadd(const vector_type, const vector_type); 28 extern gfloat Vdot(const vector_type, const vector_type); 29 extern vector_type Vmult_scalar(const vector_type, const gfloat); 30 extern gfloat Vangle(const vector_type in, const vector_type out, at_exception_type * exp); 31 32 /* These operations could have been named `P..._vector' just as well as 33 V..._point, so we may as well allow both names. */ 34 #define Padd_vector Vadd_point 35 extern at_real_coord Vadd_point(const at_real_coord, const vector_type); 36 37 #define Psubtract_vector Vsubtract_point 38 extern at_real_coord Vsubtract_point(const at_real_coord, const vector_type); 39 40 /* This returns the rounded sum. */ 41 #define IPadd_vector Vadd_int_point 42 extern at_coord Vadd_int_point(const at_coord, const vector_type); 43 44 /* Take the absolute value of both components. */ 45 extern vector_type Vabs(const vector_type); 46 47 /* Operations on points with real coordinates. It is not orthogonal, 48 but more convenient, to have the subtraction operator return a 49 vector, and the addition operator return a point. */ 50 extern vector_type Psubtract(const at_real_coord, const at_real_coord); 51 52 /* These are heavily used in spline fitting. */ 53 extern at_real_coord Padd(const at_real_coord, const at_real_coord); 54 extern at_real_coord Pmult_scalar(const at_real_coord, const gfloat); 55 56 /* Similarly, for points with integer coordinates; here, a subtraction 57 operator that does return another point is useful. */ 58 extern vector_type IPsubtract(const at_coord, const at_coord); 59 extern at_coord IPsubtractP(const at_coord, const at_coord); 60 extern at_coord IPadd(const at_coord, const at_coord); 61 extern at_coord IPmult_scalar(const at_coord, const int); 62 extern at_real_coord IPmult_real(const at_coord, const gfloat); 63 extern gboolean IPequal(const at_coord, const at_coord); 64 65 #endif /* not VECTOR_H */ 66