Surfaces - General description

On this page, you can edit surfaces and bodies.

Creating a surface

• Surfaces or other special shapes like extrusions, revolved bodies, etc., can be created starting from the already defined points. For simplicity, we will refer to all of these as surfaces.
  
  
• The program represents bodies with their bounding surfaces, not as solids.
  
  
• First, you need to create the new surface, and then specify the parameters and points.
  
  
  • Changes to the parameters are applied immediately; there is no modify button!
    
    

Surface List

You can see the already defined surfaces in this list.

• Surfaces can only be selected from this list, not from the drawing.
  
  
• Icons below the list allow you to move, delete, copy, and paste list elements.
  
  
•   The icon copies the colour of the currently selected element to all rows below it.
  
  
  • If no element is selected, the color of the first row will be applied to all.
    
    
• Multiple rows can be selected in the list at once, but only the first selected row will be considered when moving or copying.
  
  

New surface

• Clicking the new surface button creates a new surface, which by default is a front-colored polygon.
  
  
  • A new row is added to the list and is selected.
    
    
  • Then, you need to select points on the drawing and/or change the type and parameters.
    
    
• If you enable the Keep settings checkbox, the new surface will retain the previously set parameters; otherwise, it will default to (front-colored polygon).
  
  
• If you enable the Insert new surface checkbox, the new surface will be placed below the currently selected row in the list; otherwise, it will be added to the end of the list.

Properties

Colours

• Clicking any gray bar opens a window where you can choose the color or texture to assign to the surface.

• From the list on the left, you can select the type of colour to assign to the surface. For example, if you choose carcass colour, the surface will always be the currently set carcass colour.
  
  
  • The exception is the last row, direct colour. In this case, you must choose from all system colours here. This cannot be changed during use.
    
    

Types

• The top two icon rows allow you to select the type of surface. Different parameters can be applied to each type.
  Copy-paste allows parameters to be copied from one surface to another.
  
  
•   Polygons and their special cases: common area, hole cutout, inner area shading
  
  
•   Cylinder
  
  
•   General curved Bézier surface
  
  
•   Contour
  
  
•   General extrusion and its special cases: pipe, revolved body, sphere
  
  
•   Light source
  
  
•   Beginning and end joint of texturing

Line drawing

The straight-curve toggle button allows you to choose whether to continue drawing a line with a straight segment or a curve.

• The first icon undoes the last selected point.
  
  
• The 2nd and 3rd icons rotate the point order right or left. This works only as long as the line's start or end doesn't hit a curve.
  
  
• The 4th icon reverses the point order, making the end the start.
  
  
  
  

Curves

You can connect points with either straight lines or curves.

• After selecting the first point, before selecting each subsequent point, you must specify whether to continue with a straight line or a curve. A new surface always starts with a straight line.
  
  

There are two ways to draw a curve:

• Three-point curve
  A curve is drawn at the third selected point after a straight segment or the start point.
  
  
• One-point curve
  After a straight segment, selecting 1 curve point and then another straight line will create a curve between the two straight segments. The curve will always be tangent to the straight lines.
  
  
• You cannot start with a curve, but you can end with one if you close the arc to the starting straight line.
  
  

Bézier curves

• Geometrically, the curves are bézier curves.
  
  
  
  
• A bézier curve segment is defined by 4 points: the start point, the end point, and two control points. The curve is tangent to the lines connecting the endpoints to their control points (dotted line). For smooth transitions between consecutive curves without breaks, the endpoints and control points must be collinear.
  
  
  
  
• In a three-point curve, the control points can be freely moved. In a one-point curve, the control points are automatically applied by the program and are always tangents to the straight lines.
  
  
• Curves can be used not only in planes but also in space.
  
  
• Bézier curves consist of straight segments, so they can also be used to define polygons (multisided shapes).

Keywords: #surfaces #surface types #bezier curve