/// <summary>
/// Draw a 2d arrow. This function can be wrapped by ImmBegin()/ImmEnd(),
/// if you need to draw several arrows but want to limit the number of
/// draw calls. Each arrow consumes at most 9 vertices.
/// </summary>
/// <param name="start_point">Arrow's start point.</param>
/// <param name="end_point">Arrow's tip.</param>
/// <param name="ap">Arrow geometry parameters.</param>
public void DrawArrow( Vector2 start_point, Vector2 end_point, ArrowParams ap )
{
Vector2 x = end_point - start_point;
Vector2 x1 = x.Normalize();
Vector2 y1 = Math.Perp( x1 );
start_point += y1 * ap.Offset;
end_point += y1 * ap.Offset;
ap.BodyRadius *= ap.Scale;
ap.HeadRadius *= ap.Scale;
ap.HeadLen *= ap.Scale;
float r2p = ap.HeadRadius;
float r2n = ap.HeadRadius;
float r1p = ap.BodyRadius;
float r1n = ap.BodyRadius;
if ( ( ap.HalfMask & 1 ) == 0 )
{
r2n=0.0f;
r1n=0.0f;
}
if ( ( ap.HalfMask & 2 ) == 0 )
{
r2p=0.0f;
r1p=0.0f;
}
ShaderPush();
bool imm_was_active = m_imm.ImmActive;
if ( ap.BodyRadius == 0.0f
&& !imm_was_active )
{
ImmBegin( DrawMode.Lines, 2 );
ImmVertex( start_point );
ImmVertex( end_point );
ImmEnd();
}
if ( !imm_was_active )
ImmBegin( DrawMode.Triangles, 9 );
if ( ap.BodyRadius != 0.0f )
{
Vector2 p01 = start_point + r1p * y1;
Vector2 p00 = start_point - r1n * y1;
Vector2 p11 = end_point - x1 * ap.HeadLen + r1p * y1;
Vector2 p10 = end_point - x1 * ap.HeadLen - r1n * y1;
ImmVertex( p01 );
ImmVertex( p00 );
ImmVertex( p11 );
ImmVertex( p00 );
ImmVertex( p10 );
ImmVertex( p11 );
}
ImmVertex( end_point - x1 * ap.HeadLen - r2n * y1 );
ImmVertex( end_point );
ImmVertex( end_point - x1 * ap.HeadLen + r2p * y1 );
if ( !imm_was_active )
ImmEnd();
ShaderPop();
}
/// <summary>
/// Draw the coordinate system represented by a transformation matrix
/// using arrows. The x vector is represented by a red arrow, and the y
/// vector is represented by a green arrow.
/// </summary>
public void DrawCoordinateSystem2D( Matrix3 mat, ArrowParams ap = null )
{
if ( ap == null )
ap = new ArrowParams();
ShaderPush();
ImmBegin( DrawMode.Triangles, 9 * 2 );
SetColor( Colors.Red );
DrawArrow( mat.Z.Xy, mat.Z.Xy + mat.X.Xy, ap );
SetColor( Colors.Green );
DrawArrow( mat.Z.Xy, mat.Z.Xy + mat.Y.Xy, ap );
ImmEnd();
ShaderPop();
}
