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#include "geometry.h"
#include <math.h>
#include <stdlib.h>
#include <gtk/gtk.h>
void addVertex(VERTEX_LIST *list, VERTEX *v) {
list->nVertices++;
list->vertices = realloc(list->vertices, list->nVertices*sizeof(VERTEX));
list->vertices[list->nVertices-1] = *v;
}
void insertVertex(VERTEX_LIST *list, VERTEX *v, unsigned int n) {
int i;
if(n > list->nVertices)
n = list->nVertices;
list->nVertices++;
list->vertices = realloc(list->vertices, list->nVertices*sizeof(VERTEX));
for(i = list->nVertices-1; i > n; i--)
list->vertices[i] = list->vertices[i-1];
list->vertices[n] = *v;
}
void deleteVertex(VERTEX_LIST *list, unsigned int n) {
int i;
list->nVertices--;
for(i = n; i < list->nVertices; i++)
list->vertices[i] = list->vertices[i+1];
list->vertices = realloc(list->vertices, list->nVertices*sizeof(VERTEX));
}
double vertexDistanceSquare(const VERTEX *v1, const VERTEX *v2) {
return (v1->x-v2->x)*(v1->x-v2->x) + (v1->y-v2->y)*(v1->y-v2->y);
}
double vertexDistance(const VERTEX *v1, const VERTEX *v2) {
return sqrt(vertexDistanceSquare(v1, v2));
}
int vertexInRect(const VERTEX *v, const RECTANGLE *rect) {
int ret = EDGE_NONE;
if(v->x < rect->x) ret |= EDGE_LEFT;
else if(v->x >= rect->x+rect->width) ret |= EDGE_RIGHT;
if(v->y < rect->y) ret |= EDGE_TOP;
else if(v->y >= rect->y+rect->height) ret |= EDGE_BOTTOM;
return ret;
}
int lineIntersection(const LINE *la, const LINE *lb, VERTEX *v) {
double xa1 = la->v1.x, ya1 = la->v1.y;
double xa2 = la->v2.x, ya2 = la->v2.y;
double xb1 = lb->v1.x, yb1 = lb->v1.y;
double xb2 = lb->v2.x, yb2 = lb->v2.y;
double temp;
int switched = 0;
if(xa1 == xa2 && ya1 == ya2) return INTERSECTION_ERROR;
if(xb1 == xb2 && yb1 == yb2) return INTERSECTION_ERROR;
if(xa1 == xa2 || xb1 == xb2) {
temp = xa1; xa1 = ya1; ya1 = temp;
temp = xa2; xa2 = ya2; ya2 = temp;
temp = xb1; xb1 = yb1; yb1 = temp;
temp = xb2; xb2 = yb2; yb2 = temp;
switched = 1;
}
double ma = (ya2-ya1)/(xa2-xa1);
double mb = (yb2-yb1)/(xb2-xb1);
double ba = ya1 - ma*xa1;
double bb = yb1 - mb*xb1;
if(ma == mb) return (ba == bb) ? INTERSECTION_IDENTICAL : INTERSECTION_NONE;
if(isinf(ma)) {
v->x = xa1;
v->y = yb1;
}
else if(isinf(mb)) {
v->x = xb1;
v->y = ya1;
}
else {
v->x = (bb-ba)/(ma-mb);
v->y = ma*v->x + ba;
}
if(switched) {
temp = v->x; v->x = v->y; v->y = temp;
//switch back everything for segment tests
temp = xa1; xa1 = ya1; ya1 = temp;
temp = xa2; xa2 = ya2; ya2 = temp;
temp = xb1; xb1 = yb1; yb1 = temp;
temp = xb2; xb2 = yb2; yb2 = temp;
}
if(v->x < MIN(xa1,xa2) || v->x > MAX(xa1, xa2) || v->y < MIN(ya1,ya2) || v->y > MAX(ya1, ya2)) {
if(v->x < MIN(xb1,xb2) || v->x > MAX(xb1, xb2) || v->y < MIN(yb1,yb2) || v->y > MAX(yb1, yb2))
return INTERSECTION_LINE_LINE;
else
return INTERSECTION_LINE_SEGMENT;
}
else if(v->x < MIN(xb1,xb2) || v->x > MAX(xb1, xb2) || v->y < MIN(yb1,yb2) || v->y > MAX(yb1, yb2))
return INTERSECTION_SEGMENT_LINE;
else
return INTERSECTION_SEGMENT_SEGMENT;
}
int lineRectIntersection(const LINE *l, const RECTANGLE *rect, int edge, VERTEX *v) {
const double minX = rect->x, maxX = rect->x+rect->width;
const double minY = rect->y, maxY = rect->y+rect->height;
const LINE top = {{minX, minY}, {maxX, minY}};
const LINE bottom = {{minX, maxY}, {maxX, maxY}};
const LINE left = {{minX, minY}, {minX, maxY}};
const LINE right = {{maxX, minY}, {maxX, maxY}};
if((edge & EDGE_TOP) && (lineIntersection(&top, l, v) == INTERSECTION_SEGMENT_SEGMENT))
return EDGE_TOP;
if((edge & EDGE_BOTTOM) && (lineIntersection(&bottom, l, v) == INTERSECTION_SEGMENT_SEGMENT))
return EDGE_BOTTOM;
if((edge & EDGE_LEFT) && (lineIntersection(&left, l, v) == INTERSECTION_SEGMENT_SEGMENT))
return EDGE_LEFT;
if((edge & EDGE_RIGHT) && (lineIntersection(&right, l, v) == INTERSECTION_SEGMENT_SEGMENT))
return EDGE_RIGHT;
v->x = v->y = 0;
return EDGE_NONE;
}
int lineRectIntersections(const LINE *line, const RECTANGLE *rect, int edge, VERTEX *v1, VERTEX *v2) {
int ret = EDGE_NONE;
ret |= lineRectIntersection(line, rect, edge, v1);
ret |= lineRectIntersection(line, rect, EDGE_ALL^edge, v2);
return ret;
}
void simplifyPolygon(const POLYGON *in, const RECTANGLE *rect, POLYGON *out) {
int i, j;
int a;
int lastVertex, thisVertex;
VERTEX v, v2;
VERTEX_LIST vl = {0, NULL};
LINE line;
LINE d1 = {{rect->x, rect->y}, {rect->x+rect->width, rect->y+rect->height}};
LINE d2 = {{rect->x, rect->y+rect->height}, {rect->x+rect->width, rect->y}};
thisVertex = vertexInRect(&in->vertices[0], rect);
for(i = 0; i < in->nVertices; i++) {
line.v1 = in->vertices[i];
line.v2 = in->vertices[(i+1)%in->nVertices];
lastVertex = thisVertex;
thisVertex = vertexInRect(&line.v2, rect);
if(thisVertex == EDGE_NONE) {
if(lastVertex != EDGE_NONE && lineRectIntersection(&line, rect, lastVertex, &v))
addVertex(&vl, &v);
addVertex(&vl, &line.v2);
}
else if(lastVertex == EDGE_NONE) {
if(lineRectIntersection(&line, rect, thisVertex, &v))
addVertex(&vl, &v);
}
else {
a = lineRectIntersections(&line, rect, lastVertex, &v, &v2);
if((a & lastVertex) && (a & thisVertex)) {
addVertex(&vl, &v);
addVertex(&vl, &v2);
}
if(lineIntersection(&line, &d1, &v) == INTERSECTION_SEGMENT_LINE) {
if(v.x <= rect->x) addVertex(&vl, &d1.v1);
else addVertex(&vl, &d1.v2);
}
if(lineIntersection(&line, &d2, &v) == INTERSECTION_SEGMENT_LINE) {
if(v.x <= rect->x) addVertex(&vl, &d2.v1);
else addVertex(&vl, &d2.v2);
}
}
while(vl.nVertices > 0) {
a = 0;
for(j = 0; j < vl.nVertices; j++) {
if(vertexDistanceSquare(&line.v1, &vl.vertices[j]) < vertexDistanceSquare(&line.v1, &vl.vertices[a]))
a = j;
}
if(out->nVertices == 0 || out->vertices[out->nVertices-1].x != vl.vertices[a].x ||
out->vertices[out->nVertices-1].y != vl.vertices[a].y)
addVertex(out, &vl.vertices[a]);
deleteVertex(&vl, a);
}
}
}
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