// http://www.geometrictools.com/Documentation/MinimumAreaRectangle.pdf
public static void ComputeOBB(out OBB obb, Vec2[] vs, int count)
{
obb = new OBB();
Box2DXDebug.Assert(count <= Settings.MaxPolygonVertices);
Vec2[] p = new Vec2[Settings.MaxPolygonVertices + 1];
for (int i = 0; i < count; ++i)
{
p[i] = vs[i];
}
p[count] = p[0];
float minArea = Common.Settings.FLT_MAX;
for (int i = 1; i <= count; ++i)
{
Vec2 root = p[i - 1];
Vec2 ux = p[i] - root;
float length = ux.Normalize();
Box2DXDebug.Assert(length > Common.Settings.FLT_EPSILON);
Vec2 uy = new Vec2(-ux.Y, ux.X);
Vec2 lower = new Vec2(Common.Settings.FLT_MAX, Common.Settings.FLT_MAX);
Vec2 upper = new Vec2(-Common.Settings.FLT_MAX, -Common.Settings.FLT_MAX);
for (int j = 0; j < count; ++j)
{
Vec2 d = p[j] - root;
Vec2 r = new Vec2();
r.X = Vec2.Dot(ux, d);
r.Y = Vec2.Dot(uy, d);
lower = Common.Math.Min(lower, r);
upper = Common.Math.Max(upper, r);
}
float area = (upper.X - lower.X) * (upper.Y - lower.Y);
if (area < 0.95f * minArea)
{
minArea = area;
obb.R.Col1 = ux;
obb.R.Col2 = uy;
Vec2 center = 0.5f * (lower + upper);
obb.Center = root + Common.Math.Mul(obb.R, center);
obb.Extents = 0.5f * (upper - lower);
}
}
Box2DXDebug.Assert(minArea < Common.Settings.FLT_MAX);
}
public static void ComputeOBB(out OBB obb, Vec2[] vs, int count)
{
obb = default(OBB);
Box2DXDebug.Assert(count <= Settings.MaxPolygonVertices);
Vec2[] array = new Vec2[Settings.MaxPolygonVertices + 1];
for (int i = 0; i < count; i++)
{
array[i] = vs[i];
}
array[count] = array[0];
float num = Settings.FLT_MAX;
for (int i = 1; i <= count; i++)
{
Vec2 vec = array[i - 1];
Vec2 vec2 = array[i] - vec;
float num2 = vec2.Normalize();
Box2DXDebug.Assert(num2 > Settings.FLT_EPSILON);
Vec2 vec3 = new Vec2(-vec2.Y, vec2.X);
Vec2 vec4 = new Vec2(Settings.FLT_MAX, Settings.FLT_MAX);
Vec2 vec5 = new Vec2(-Settings.FLT_MAX, -Settings.FLT_MAX);
for (int j = 0; j < count; j++)
{
Vec2 b = array[j] - vec;
Vec2 b2 = default(Vec2);
b2.X = Vec2.Dot(vec2, b);
b2.Y = Vec2.Dot(vec3, b);
vec4 = Box2DX.Common.Math.Min(vec4, b2);
vec5 = Box2DX.Common.Math.Max(vec5, b2);
}
float num3 = (vec5.X - vec4.X) * (vec5.Y - vec4.Y);
if (num3 < 0.95f * num)
{
num = num3;
obb.R.Col1 = vec2;
obb.R.Col2 = vec3;
Vec2 v = 0.5f * (vec4 + vec5);
obb.Center = vec + Box2DX.Common.Math.Mul(obb.R, v);
obb.Extents = 0.5f * (vec5 - vec4);
}
}
Box2DXDebug.Assert(num < Settings.FLT_MAX);
}
