selfImDrawList handle on which this method operates.
p1Ordered vertex or start point p1 in absolute screen coordinates.
p2Ordered vertex or start point p2 in absolute screen coordinates.
p3Ordered vertex or start point p3 in absolute screen coordinates.
p4Ordered vertex or start point p4 in absolute screen coordinates.
colPacked ImU32 RGBA color; alpha controls opacity.
thicknessStroke thickness in screen pixels.
Append the outline of a quadrilateral to the draw list.