diff options
| -rw-r--r-- | src/math.c | 58 | ||||
| -rw-r--r-- | src/math.h | 1 |
2 files changed, 59 insertions, 0 deletions
@@ -64,3 +64,61 @@ radians points_to_angle(c2_t p1,c2_t p2) { real a=atan2(p2.y-p1.y,p2.x-p1.x); return (radians){a>=0?a:M_PI+M_PI+a}; } + +int between_angles(degrees d,real lower,real upper) { + //lower may be higher than upper. + //because lower is < 0 which wraps to higher. lower is 270, upper is 90. 270-90 is in front. + if(lower > upper) { + if(d.d > lower) return 1; + if(d.d < upper) return 1; + } + if(upper > lower) { + if(d.d > lower && d.d < upper) return 1; + } + return 0; +} + +int points_on_same_side_of_line(c2_t p1,c2_t p2,c2_t p3,c2_t p4) {//we're going to check if... well, the name says it all. +// if(s.len != 2) //well... I guess we'll just use the first two points anyway. + degrees la=r2d(points_to_angle(p3,p4)); + degrees p1a=r2d(points_to_angle(p3,p1)); + degrees p2a=r2d(points_to_angle(p3,p2)); + //p1aa= + //now... + //between angles. if the line's angle is between the points' angles they're on opposite sides + if(between_angles(la,p1a.d,p2a.d)) { + return 1; + } + return 0; +} + +//if a shape's angle between points continues to grow only in one direction the shape is convex. +//like for a square the angles would be 90,90,90,90 or -90,-90,-90,-90 +//but if we end up with something like 90,90,-90,90,90,90 then we have concave. +//this could be used in a loop and then cut polygons into convex before loading them into the shapes array. +//not sure how I'm going to do this for 3d shapes... not needed I guess. this is for mouse-inside-shape +//after it has already been flattened. so it can't be used before they're loaded. +//has to be done at run-time with the 2d shapes that are in either c2 or cs format. +int is_shape_concave() { + //a; + //b; + //a= + //for(i=1;i<s.len;i++) { + // b=points_to_angle(s.p[i],s.p[(i+1)%s.len]); + // if(b < a) //figure out which direction the points are bending and if we bend the other direction then we're concave. + //} + return 0; +} + +int point_inside_concave_shape(c2_t p1,c2_s_t s) {//hrm... + //the point must be on the inside side of all lines to be inside. + //if(s.len == 1) //as long as distance from the center is less than the radius we're in. + //else { + int i; + for(i=0;i<s.len;i++) { + //if(!points_on_same_side_of_line()) { + // return 0; + //} + } + return 1; +} @@ -18,5 +18,6 @@ c3_group_rot_t *get_group_rotation(char *id); radians d2r(degrees d); degrees r2d(radians r); radians points_to_angle(c2_t p1,c2_t p2); +int between_angles(degrees d,real lower,real upper); #endif |