I wish to enquire whether the suppose i specify 3 points to draw a curve, the 1st is start point, the 2nd is end point of the curve. the last point (middle part of curve): does it actually lie on the curve or it is just a point that pulls the curve towards it?
I understand that evaluators uses the start, end and control points to draw a 3D surface.The control points do not lie on the surface itself so to draw a 3D 1/4 hollow cylinder. What should the middle control point be? i tried these points:
assumming d is radius of cylinder. But somehow it doesn't look that accurate. In addition the following code work when i use GL_LINE but not if i change it to GL_FILL, how do i resolve this?
// the setup function
glMap2f(GL_MAP2_VERTEX_3, // Type of data generated
0.0f, // Lower u range
10.0f, // Upper u range
3, // Distance between points in the data
3, // Dimension in u direction (order)
0.0f, // Lower v range
10.0f, // Upper v range
9, // Distance between points in the data
3, // Dimension in v direction (order)
&ctrlPoints); // array of control points
// Enable the evaluator
// Map a grid of 100 points from 0 to 100
// Evaluate the grid, using lines
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