arc_path.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "VG/openvg.h"
#include "VG/vgu.h"
#include "fontinfo.h"
#include "shapes.h"
#include <math.h>

void MakeArc(VGfloat x, VGfloat y, VGfloat r, VGfloat sa, VGfloat ext,
             VGubyte **segments, int *seg_size,
             VGfloat **coordinates, int *coord_size)
{
  VGfloat xpos(VGfloat x, VGfloat r, VGfloat a)
  {
    VGfloat t = a * M_PI / 180.0f;
    return x + r * cosf(t);
  }
  VGfloat ypos(VGfloat y, VGfloat r, VGfloat a)
  {
    VGfloat t = a * M_PI / 180.0f;
    return y + r * sinf(t);
  }
  const int divs = 20;
  VGubyte *segs = malloc(sizeof(VGubyte) * (divs + 1));
  VGfloat *coords = malloc(sizeof(VGfloat) * (divs + 1) * 2);
  segs[0] = VG_MOVE_TO;
  coords[0] = xpos(x, r, sa); coords[1] = ypos(y, r, sa);
  int ss = 1, cs = 2;
  for (int i = 0; i < divs; i++) {
    sa += ext / divs;
    if (sa < 0.0f) sa += 360.0f;
    else if (sa >= 360.0f) sa -= 360.0f;
    segs[ss++] = VG_LINE_TO;
    coords[cs++] = xpos(x, r, sa);
    coords[cs++] = ypos(y, r, sa);
  }
  *segments = segs;
  *coordinates = coords;
  *seg_size = ss;
  *coord_size = cs;
}

void DrawObj(VGubyte *inSegments, int inSegments_size,
             VGfloat *inCoords, int inCoords_size,
             VGubyte *outSegments, int outSegments_size,
             VGfloat *outCoords, int outCoords_size)
{
  int AllSegments_size = outSegments_size + 1 + 1 + 1 + inSegments_size;
  int AllCoords_size = outCoords_size + 2 + 2 + 2 + inCoords_size;
  VGubyte *AllSegments = (VGubyte*)malloc(sizeof(VGubyte) * AllSegments_size);
  VGfloat *AllCoords = (VGfloat*)malloc(sizeof(VGfloat) * AllCoords_size);
  int AllSegments_index = 0;
  int AllCoords_index = 0;
  for (int i = 0; i < outSegments_size; i ++) {
    AllSegments[AllSegments_index] = outSegments[i];
    AllSegments_index ++;
  }
  for (int j = 0; j < outCoords_size; j ++) {
    AllCoords[AllCoords_index] = outCoords[j];
    AllCoords_index ++;
  }
  
  inSegments[0] = VG_LINE_TO;
  for (int i = 0; i < inSegments_size; i ++) {
    AllSegments[AllSegments_index] = inSegments[i];
    AllSegments_index ++;
  }
  for (int j = 0; j < inCoords_size; j ++) {
    AllCoords[AllCoords_index] = inCoords[j];
    AllCoords_index ++;
  }
  AllSegments[AllSegments_index] = VG_CLOSE_PATH;

  VGPath path = vgCreatePath(VG_PATH_FORMAT_STANDARD, VG_PATH_DATATYPE_F, 1.0f, 0.0f, 0, 0, VG_PATH_CAPABILITY_APPEND_TO);
  vgAppendPathData(path, AllSegments_size, AllSegments, AllCoords);
  vgRemovePathCapabilities(path, VG_PATH_CAPABILITY_APPEND_FROM | VG_PATH_CAPABILITY_APPEND_TO |
      VG_PATH_CAPABILITY_MODIFY | VG_PATH_CAPABILITY_TRANSFORM_FROM |
      VG_PATH_CAPABILITY_TRANSFORM_TO | VG_PATH_CAPABILITY_INTERPOLATE_FROM |
      VG_PATH_CAPABILITY_INTERPOLATE_TO);

  free(AllSegments);
  free(AllCoords);
  vgDrawPath(path, VG_STROKE_PATH | VG_FILL_PATH);
  vgDestroyPath(path);
}

int main() {
  int width, height;
  char s[3];
  init(&width, &height);

  Start(width, height);
  Background(0, 0, 0);
  Fill(44, 77, 232, 1);
  Stroke(255, 255, 255, 1);
  StrokeWidth(2);

  VGubyte *outSeg, *inSeg;
  VGfloat *outCoord, *inCoord;
  int outSeg_size, inSeg_size, outCoord_size, inCoord_size;
  MakeArc(width / 2.0f, height / 2.0f, height / 4.0f, 200.0f, -160.0f, &outSeg, &outSeg_size, &outCoord, &outCoord_size);
  VGPath outerArc = vgCreatePath(VG_PATH_FORMAT_STANDARD, VG_PATH_DATATYPE_F, 1.0f, 0.0f, outSeg_size, outCoord_size, VG_PATH_CAPABILITY_APPEND_TO);
  vgAppendPathData(outerArc, outSeg_size, outSeg, outCoord);

  MakeArc(width / 2.0f , height / 2.0f, height / 4.5f, 40.0f, 160.0f, &inSeg, &inSeg_size, &inCoord, &inCoord_size);
  VGPath inArc = vgCreatePath(VG_PATH_FORMAT_STANDARD, VG_PATH_DATATYPE_F, 1.0f, 0.0f, inSeg_size, inCoord_size, VG_PATH_CAPABILITY_APPEND_TO);
  vgAppendPathData(inArc, inSeg_size, inSeg, inCoord);

  DrawObj(inSeg, inSeg_size, inCoord, inCoord_size, outSeg,
          outSeg_size, outCoord, outCoord_size);
  //  vgDrawPath(outerArc, VG_STROKE_PATH);
  //  vgDrawPath(inArc, VG_STROKE_PATH);
  End();

  fgets(s, 2, stdin);
  finish();
}