// Calculate minimum extend of the polygon.
static float polyMinExtent(const float* verts, const int nverts)
{
float minDist = FLT_MAX;
for (int i = 0; i < nverts; i++)
{
const int ni = (i+1) % nverts;
const float* p1 = &verts[i*3];
const float* p2 = &verts[ni*3];
float maxEdgeDist = 0;
for (int j = 0; j < nverts; j++)
{
if (j == i || j == ni) continue;
float d = distancePtSeg2d(&verts[j*3], p1,p2);
maxEdgeDist = rcMax(maxEdgeDist, d);
}
minDist = rcMin(minDist, maxEdgeDist);
}
return rcSqrt(minDist);
}
int rcOffsetPoly(const float* verts, const int nverts, const float offset,
float* outVerts, const int maxOutVerts)
{
const float MITER_LIMIT = 1.20f;
int n = 0;
for (int i = 0; i < nverts; i++)
{
const int a = (i+nverts-1) % nverts;
const int b = i;
const int c = (i+1) % nverts;
const float* va = &verts[a*3];
const float* vb = &verts[b*3];
const float* vc = &verts[c*3];
float dx0 = vb[0] - va[0];
float dy0 = vb[2] - va[2];
float d0 = dx0*dx0 + dy0*dy0;
if (d0 > 1e-6f)
{
d0 = 1.0f/rcSqrt(d0);
dx0 *= d0;
dy0 *= d0;
}
float dx1 = vc[0] - vb[0];
float dy1 = vc[2] - vb[2];
float d1 = dx1*dx1 + dy1*dy1;
if (d1 > 1e-6f)
{
d1 = 1.0f/rcSqrt(d1);
dx1 *= d1;
dy1 *= d1;
}
const float dlx0 = -dy0;
const float dly0 = dx0;
const float dlx1 = -dy1;
const float dly1 = dx1;
float cross = dx1*dy0 - dx0*dy1;
float dmx = (dlx0 + dlx1) * 0.5f;
float dmy = (dly0 + dly1) * 0.5f;
float dmr2 = dmx*dmx + dmy*dmy;
bool bevel = dmr2 * MITER_LIMIT*MITER_LIMIT < 1.0f;
if (dmr2 > 1e-6f)
{
const float scale = 1.0f / dmr2;
dmx *= scale;
dmy *= scale;
}
if (bevel && cross < 0.0f)
{
if (n+2 >= maxOutVerts)
return 0;
float d = (1.0f - (dx0*dx1 + dy0*dy1))*0.5f;
outVerts[n*3+0] = vb[0] + (-dlx0+dx0*d)*offset;
outVerts[n*3+1] = vb[1];
outVerts[n*3+2] = vb[2] + (-dly0+dy0*d)*offset;
n++;
outVerts[n*3+0] = vb[0] + (-dlx1-dx1*d)*offset;
outVerts[n*3+1] = vb[1];
outVerts[n*3+2] = vb[2] + (-dly1-dy1*d)*offset;
n++;
}
else
{
if (n+1 >= maxOutVerts)
return 0;
outVerts[n*3+0] = vb[0] - dmx*offset;
outVerts[n*3+1] = vb[1];
outVerts[n*3+2] = vb[2] - dmy*offset;
n++;
}
}
return n;
}