#!/usr/bin/python
# Naming conventions follow RhinoScript, not PEP8.

import rhinoscriptsyntax as rs


def Main():
    """Draw a surface and a cone and then render both objects."""
    DrawSurface()
    DrawCone()
    RenderObjects()


def DrawSurface():
    """Draw a rendered NURBS surface using four edge curves."""

    # Set the corners at the base of the surface in the x-y plane.
    frontLeftCorner = (-12,-6,0)
    frontRightCorner = (12,-6,0)
    rearLeftCorner = (-6,10,0)
    rearRightCorner = (6,10,0)

    # Set first/last `degree` knots to force curves to start/end at corners.
    degree = 3
    knots = (0, 0, 0, 1, 2, 3, 4, 4, 4)

    # Vary the control point heights in the z direction based on the edge.
    frontHeights = (0, 7, 10, 12, 10, 7, 0)
    rearHeights = (0, 1, 2, 3, 2, 1, 0)
    leftHeights = (0, 2, 3, 3, 2, 1, 0)
    rightHeights = leftHeights

    # Create the control points for each edge.
    frontPoints = CreatePoints(frontLeftCorner, frontRightCorner, frontHeights)
    rearPoints = CreatePoints(rearLeftCorner, rearRightCorner, rearHeights)
    leftPoints = CreatePoints(frontLeftCorner, rearLeftCorner, leftHeights)
    rightPoints = CreatePoints(frontRightCorner, rearRightCorner, rightHeights)

    # Create NURBS curves for each edge.
    frontEdge = rs.AddNurbsCurve(frontPoints, knots, degree)
    rearEdge = rs.AddNurbsCurve(rearPoints, knots, degree)
    leftEdge = rs.AddNurbsCurve(leftPoints, knots, degree)
    rightEdge = rs.AddNurbsCurve(rightPoints, knots, degree)

    # Create a NURBS surface using (a tuple of) the edges.
    return rs.AddEdgeSrf((frontEdge, leftEdge, rearEdge, rightEdge))


def DrawCone():
    """Create a cone in front of the surface to show orientation."""
    return rs.AddCone((0,-13,0), (0,-13,2), 1)


def RenderObjects():
    """Render the objects in all views."""
    views = rs.ViewNames()
    for view in views:
        rs.ViewDisplayMode(view, 'Rendered')


def CreatePoints(start, end, h):
    """Return points between start and end in x and y, with z from h."""
    points = []
    for i in xrange(len(h)):
        points.append(CreatePoint(start, end, h, i))
    return points


def CreatePoint(start, end, h, i):
    """Return i^th point between start and end, with z taken from h."""
    scalingFactor = float(i)/float(len(h)-1)
    x = start[0] + scalingFactor * (end[0] - start[0])
    y = start[1] + scalingFactor * (end[1] - start[1])
    z = h[i]
    return (x, y, z)


# Invoke if this is run as a script.
if( __name__ == "__main__" ):
    Main()