Modeling with 3D Polygons, Slabs, and Blocks

Transcription

1 Modeling with 3D Polygons, Slabs, and Blocks DataCAD s 3D polygons, slabs and blocks are closely related entities with a few important differences. A 3D polygon is a single entity with no thickness (unlike a 2D polygon, which is a group of lines drawn from Z-base to Z-height). Slabs, usually the most common entity in a model, are very similar to polygons, except that they have a thickness that you can specify. Blocks are simple solids with six rectangular or parallelogram-shaped faces. Because the top of a block doen t have to lie directly over its bottom, blocks are particularly useful for modeling support members that lean to one side. Another important distinction between 3D polygons and slabs is that slabs have a reference face, which is the face of the slab that orients the slab, controls the direction that you can pass a void through the slab, and is important when moving or adding vertices or voids to a slab. DataCAD automatically assigns one face of a slab to be the reference face, depending on what kind of slab you draw: In this chapter: 21 Drawing horizontal and vertical 3D polygons Drawing horizontal and vertical slabs Using inclined polygons and slabs to draw roofs Adding voids to 3D polygons and slabs Editing 3D polygons and slabs Drawing blocks Horizontal slabs If you draw the slab from Z-base with the specified thickness (Base+Thk toggle), the reference face is at Z-base. If you draw the slab from Z-height with the specified thickness (Hgt+Thk toggle), the reference face is at Z-height. If you draw the slab from Z-base to Z-height (Base/Hgt toggle), the reference face is at Z-base. Vertical slabs When you draw a slab from the top of the screen to the bottom, the reference face in on the left. When you draw a slab from the bottom of the screen to the top, the reference face in on the right. Inclined slabs The reference face is always on the underside of the slab. If you forget which face of a slab is the reference face, toggle SlabRefs on in the 3DEdit/Settings menu. Dots will be displayed on every vertice of each reference face, along with an additional dot on one of the opposite vertices.

2 406 CHAPTER 21: MODELING WITH 3D POLYGONS, SLABS, AND BLOCKS Drawing Rectangular 3D Polygons and Slabs To draw a rectangular 3D polygon: 1. Choose RectAngl from the Polygon menu. 2. Choose a Z elevation (Z-Base, Z-Hgt, Z-User1, or Z-User2) at which to draw the rectangle. To set the alternative Z elevations, choose SetZUsr1 to set the Z-User1 elevation or choose SetZUsr2 to set the Z-User2 elevation. 3. Select a point to start the rectangle. 4. Drag the cursor diagonally to size the rectangle and click. The rectangle is drawn. You can also create rectangular polygons with Horizntl, but using RectAngl is faster and easier. To draw rectangular slabs: 1. Choose RectAngl from the Slab menu. 2. Choose a Z elevation at which to draw the rectangular slab: from Z-base to a thickness (Base+Thk), from Z-height to a thickness (Hgt+Thk), or from Z-base to Z-height (Base/Hgt). 3. Determine if you are using Base+Thk or Hgt+Thk to draw slabs. Set the thickness value by choosing Thicknss from the RectAngl menu and then choosing or typing a value and pressing (Enter). As with all Z measurements, a positive thickness extends out of the screen and a negative thickness extends into the screen. 4. Select a point to start the rectangle. 5. Drag the cursor diagonally to size the slab and click. The slab appears. You can also create rectangular slabs with Horizntl, but using RectAngl is faster and easier. Drawing Horizontal 3D Polygons and Slabs To draw horizontal 3D polygons: 1. Choose Horizntl from the Polygon menu. 2. Choose the elevation at which you want to draw the polygon: Z-base, Z- height (Z-Hgt), or one of the two alternative Z elevations (Z-User1 or Z- User2). These alternative Z elevations are set using the SetZUsr1 and SetZUsr2 options in the menu, respectively. To set the height of an alternative Z elevation, choose SetZUsr1 or SetZUsr2 from the Polygon menu, and then choose or type a height value and press (Enter). See Z- Base and Z-Height in the Modeling Basics chapter for details about Z- elevations. 3. Select the first point of the polygon. You can create polygons of up to 36 vertices this way.

3 DRAWING HORIZONTAL 3D POLYGONS AND SLABS Continue selecting points until you are ready to close the polygon. If you make a mistake in placing a vertex, use Backup to erase the last selected point. Use Backup to erase the last side of the polygon you drew. Backup is available as soon as you select the first point of a polygon and until you close the polygon or right-click to disconnect from the polygon you re drawing. To cancel the polygon before the polygon is completed and added to the drawing, choose Cancel. Use Cancel to erase the polygon you re currently drawing. Cancel is only available after you select the third point of the polygon and until you close the polygon or right-click to disconnect from the polygon you re drawing. You can also choose Exit, which is available until you select the third point of the polygon, when it becomes Close. Use Exit to stop drawing a polygon and erase what you ve drawn to that point. If you create a 36-vertex polygon, DataCAD closes the polygon for you. To circumvent this 36-vertex limitation, see Editing 3D Polygons and Slabs later in this chapter. 5. Connect the last point you selected with the first one and close the polygon by choosing Close or right-clicking. To draw horizontal slabs: 1. Choose Horizntl from the Slab menu. 2. Choose the elevation at which you want to draw the slab: Z-base extending to a thickness (Base+Thk), Z-height extending to a thickness (Hgt+Thk), or Z-base extending to Z-height (Base/Hgt). Backup is available as soon as you select the first point of a slab and until you close the slab or right-click to disconnect from the slab you re drawing. 3. Set a thickness for the slab by choosing Thicknss from the Horizntl menu. Then choose or type a value and press (Enter). As with all Z measurements, a positive thickness extends out of the screen and a negative thickness extends into the screen. Set Thicknss when you are drawing slabs with Base+Thk or Hgt+Thk; otherwise, the Thicknss setting is ignored. 4. Select the first point or vertex of the slab. You can create slabs of up to 36 vertices. If you create a 36-vertex slab, DataCAD closes the slab for you. If you make a mistake in placing a vertex, use Backup to remove the last vertex you entered and then continue to place vertices. Use Exit to stop drawing a polygon and erase what you ve drawn to that point. After you select the third point of the polygon, the Exit option changes to Close. See Editing 3D Polygons and Slabs later in this chapter for more information about simulating polygons or slabs with more than 36 sides. 5. Select a second corner point that, along with the first point, forms an edge for the base of the block. 6. Choose Cancel if you want to cancel the slab before it is completed and added to the drawing. Cancel is only available after you select the third point of the slab and until you close the slab or right-click to disconnect from the slab you re drawing.

4 408 CHAPTER 21: MODELING WITH 3D POLYGONS, SLABS, AND BLOCKS 7. Use Close if you want to connect the last point you selected with the first one and finish the slab. Drawing Vertical 3D Polygons and Slabs Vertical polygons and slabs are rectangular shapes drawn edge on. Vertical polygons are useful for quickly creating forms that show some kind of extruded quality, like gutters or irregular curtain walls, while vertical slabs are useful for quickly creating free-standing walls. Draw the edge of the vertical polygon or slab by selecting points on the screen; the height of the entity is determined by the separation of Z-base and Z-height (or the two alternative Z elevations). To draw a vertical 3D polygon: 1. Choose Vertical from the Polygon menu. 2. Choose to draw the polygon from Z-base to Z-height (Base/Hgt) or from Z alternative 1 to Z alternative 2 (Z1/Z2). These toggles set the height of the vertical polygon to run from one Z elevation to the other (from Z-base to Z-height or from Z1 to Z2). To set the height of the Z1 or Z2 elevation, choose Z-User1 or Z-User2 from the Polygon menu, and then choose or type a height value and press (Enter). 3. Choose Chain to create vertical polygons in succession, with the first edge of each polygon connected to the last edge of the previous polygon. This is similar to the way 2D lines are drawn. When you toggle Chain off, DataCAD does not automatically connect lines, so you must select both points of each polygon edge you draw. 4. Select two points on the screen creating one edge of the vertical polygon. The polygon is drawn upright, into or out of the screen. Figure 21.1: Vertical polygons To draw a vertical slab: 1. Choose Vertical from the Slab menu. 2. Choose to draw the slab from Z-base to Z-height (Base/Hgt) or from Z- alternative 1 to Z-alternative 2 (Z1/Z2). These toggles set the height of the vertical slab to run from one Z elevation to the other; they are mutually exclusive. To set the values of Z-alternative 1 and Z-alternative 2, choose Z-User1 or Z-User2 from the Vertical menu, and then choose a value from the list or type a value and press (Enter). 3. Set the thickness of the slab by choosing Thicknss from the Vertical menu. Then choose or type a value and press (Enter). Do not confuse this setting with the Thicknss setting in Horizontal and Rectangular slabs. Thickness for vertical slabs refers to the short dimension of the slab as seen across the screen, not the depth of the slab going into the screen.

5 DRAWING VERTICAL 3D POLYGONS AND SLABS Choose Left, Center, or Right to determine the side of the slab on which to attach the cursor. The terms Left, Center, and Right refer to the slab as drawn from the top of the screen toward the bottom. If you draw the slab from the bottom to the top with Left toggled on, your cursor appears attached to the right side of the slab. These toggles are mutually exclusive and can be activated at any time, even after you select the first point of the slab. Left Center Right Figure 21.2: Cursor positions on vertical slabs 5. Select the first corner point of the vertical slab. 6. Move the cursor diagonally to the opposite point of the slab. The slab sizes dynamically with the cursor. Click to complete the slab. The slab is drawn upright, between the two elevations you selected in step 2. Figure 21.3: Vertical slabs Use SlabRefs to display markers that indicate the reference face for a slab as well as the direction of extrusion. The reference face of the slab is determined by the points selected on the screen. The extrusion is determined by the relative Z-base and Z-height (or Z-User1 or Z-User2) settings you have entered. C D E B A Reference Face = ABCD ExtrusionValue =AE Zbase =A Zheight =E Figure 21.4: Reference faces Whencreatingvoids, thereferencefacesofthemaster andsecondary slabsmustbeinthesameplane, andtheirextrusionvaluesmust beequal.

6 410 CHAPTER 21: MODELING WITH 3D POLYGONS, SLABS, AND BLOCKS Drawing Inclined 3D Polygons and Slabs Inclined polygons can be used to create roof elements. Roofs that you create with this menu do not have a thickness. To create roofs with thickness, use the Inclines menu in the 3DEntity/Slab menu, or use the RoofIt tool available from the Toolbox menu to create simple roofs automatically. To create roof elements using inclined polygons: 1. Use the 3DViews option from the Polygon menu to place the model in an orthographic view. 2. Set Z-Base to the height of the lowest point on the roof. 3. Set Z-Hgt to the height of the ridge line (peak) of the roof. DataCAD needs Z-base and Z-height information about the roofs that you are going to create information that is easily calculated but not immediately at hand. Calculate the heights and breadths of roofs before using the Inclines menu. 4. Choose Inclines from the Polygon menu. 5. Continue with the sections below to draw the three- or four-edged inclined polygon you need. To create roof elements using inclined slabs: 1. Place the model into orthographic (plan) view. 2. Choose Inclines from the Slab menu. 3. Choose Thicknss to set the depth of the roof element; choose or type a value and press (Enter). 4. Choose whether to add the thickness perpendicularly or vertically. Vertical adds the thickness of the slab to the roof element vertically, or perpendicular to the ground. This produces a plumb cut on the edge of the roof element. Perpend adds the thickness of the slab to the roof perpendicularly to the roof slope. 5. Continue with the instructions below to draw the three- or four-edged inclined slab you need. To draw gable, A-frame, and shed roofs: 1. Choose 4EdgPara from the Inclines menu. 2. Select the first corner point at the bottom edge of the slope. 3. Select the second corner point at the bottom edge of the slope. 4. Select the first corner point on the ridge of the roof. Enter this third point opposite the first point, as shown below. Locate this point by snapping or with a reference point shortcut and coordinate entry. The fourth corner point is automatically derived.

7 DRAWING INCLINED 3D POLYGONS AND SLABS Figure 21.5: Four-edged parallelograms To draw hip and mansard roofs: 1. Choose 4EdgTrap from the Inclines menu. 2. Select the first corner point at the bottom edge of the slope. 3. Select the second corner point at the bottom edge of the slope. 4. Select the first corner point on the ridge of the roof. Enter this third point opposite the first point, as shown below. Locate this point by snapping or with a reference point shortcut and coordinate entry. The fourth corner point is automatically derived Figure 21.6: Four-edged trapezoids When a portion of a roof has four edges, but the opposite edges are not parallel due to unusual intersections or valleys with other roofing elements, use the fouredged general inclined polygon or slab option.

8 412 CHAPTER 21: MODELING WITH 3D POLYGONS, SLABS, AND BLOCKS To draw dormers and other unusual roofs: 1. Choose 4EdgGen from the Inclines menu. 2. Select the first corner point at the bottom edge of the slope. 3. Select the second corner point at the bottom edge of the slope. 4. Select the first corner point on the ridge of the roof. Enter this third point opposite the first point, as shown below. Locate this point by snapping or with a reference point shortcut and coordinate entry. 5. Select the last corner point on the ridge of the roof Figure 21.7: Four-edged general incline To draw the triangular pieces of hip roofs: 1. Choose 3EdgBot from the Inclines menu. 2. Select the first point at the bottom edge of the slope (at Z-base). 3. Select the second corner point at the bottom edge of the slope (also at Z- base). 4. Select the corner point on the ridge of the roof (at Z-height). Locate this point by snapping or with a reference point shortcut and coordinate entry Figure 21.8: Three-edged bottom incline

9 To draw simple dormers: 1. Choose 3EdgTop from the Inclines menu. DRAWING INCLINED 3D POLYGONS AND SLABS Select the first corner point on the ridge of the roof (at Z-height). 3. Select the second corner point on the ridge of the roof (also at Z-height). Locate this point by snapping or with a reference point shortcut and coordinate entry. 4. Select the corner point at the bottom edge of the slope (at Z-base) Figure 21.9: Three-edged top incline The four-edged vertical incline is created edge on, very much like the vertical polygon or slab, except that the incline has an independent thickness associated with it that controls the depth of the beam. To draw rafters using vertical inclined polygons or slabs: 1. Choose 4EdgVert from the Inclines menu. 2. Choose Thicknss to set the depth of the polygon or slab (rafter). A list of values appears. 3. Choose or type a value and press (Enter). 4. Select the location for the lower edge of the polygon or slab, or the base of the incline, including the thickness of the polygon or slab. 5. Select the location for the upper edge of the polygon or slab, or the top of the incline. The polygon or slab ends at the Z-height, including the thickness of the polygon or slab.

10 414 CHAPTER 21: MODELING WITH 3D POLYGONS, SLABS, AND BLOCKS Z-Height of 17'-0" Z-Height of 16'-0" Z-Base of 9'-0" Z-Base of 8'-0" 1 Plan Elevation Figure 21.10: Four-edged vertical incline To create three-edged vertical, inclined polygons or slabs: 1. Choose 3EdgPoly from the Inclines menu. 2. Set the thickness of the slab using the Thicknss option if you re drawing a slab. 3. Snap to the first corner point on the incline. Use the 3D cursor to snap to the corners of roof elements already in place. You don t have to select the points in any particular order. 4. Snap to the second corner point on the incline. 5. Snap to the third corner point on the incline. The polygon or slab is drawn. Adding Voids to Polygons and Slabs The Voids menu in the Polygon and Slab menus has options for creating and deleting holes in polygons and slabs. You create a void by drawing a small polygon or slab (representing the void) inside a larger (primary) polygon or slab. The smaller polygon or slab is then converted into a void with the AddVoid option. When creating slabs, the reference face of each void must coincide exactly with the reference face of the primary slab, and the voids must be exactly as thick as the primary slab. To add a void: 1. Draw a primary polygon or slab (the polygon or slab you will be adding a void to). Use PlneSnap, NewElev, or EditPlne (in the 3DViews menu) to bring the primary polygon or slab into the zero plane before adding voids. When you create both the primary and void polygons or slabs without changing the view, they automatically lie in the same plane.

11 ADDING VOIDS TO POLYGONS AND SLABS Draw the void polygon or slab inside the primary polygon or slab in exactly the same plane, at Z-base (or whatever Z elevation you drew the primary polygon or slab at) equal to zero. You can draw more than one void polygon or slab at this time. Make sure the void polygon or slab lies completely within the primary polygon or slab. 3. Choose Voids from the Polygon or Slab menu. 4. Highlight the primary polygon or slab by selecting one of its edges. 5. Choose AddVoid. 6. Select the void polygon(s) or slab(s) you drew in step 2. The void polygons or slabs are highlighted as you select them. The primary polygon or slab now has voids in it. When you add a void to a polygon or slab, you are left with one entity (a polygon or slab with a hole in it) where separate polygons or slabs existed before. If you erase or move the primary polygon or slab, the void moves with it, as you would expect of a single entity. The void polygons or slabs no longer have an identity apart from the primary polygon or slab to which they belong. Use ConvVoid to convert voids back into the polygons or slabs from which they originated. You must convert a void when you want to edit the void by adding, deleting, or moving vertices using the Partial menu. To convert a void: 1. Select Voids from the Polygon or Slab menu. 2. Select a primary polygon or slab by indicating one of its edges. The primary polygon or slab and any voids are highlighted. 3. Choose ConvVoid from the Voids menu. 4. Select the voids that you want to convert back into polygons or slabs. Any converted voids now exist as individual, embedded polygons or slabs. To add vertices to a void, convert the void back into a polygon or slab with ConVoid, add vertices with AddVertx from the Partial menu, then use AddVoid to turn the polygon or slab back into a void. You can also move a void or resize it using 3DEdit/Stretch. Once you add a void to a primary polygon or slab, the void polygon or slab no longer exists as an independent entity; it becomes a hole in a larger object. Use ErasVoid to remove these voids from a primary polygon or slab. To erase a void: 1. Choose Voids from the Polygon or Slab menu. 2. Select the primary polygon or slab by indicating one of its edges. The polygon or slab and any voids are highlighted. 3. Choose ErasVoid from the Voids menu. 4. Select the voids that you want to delete from the polygon or slab. Selected voids disappear entirely, sealing the hole.

12 416 CHAPTER 21: MODELING WITH 3D POLYGONS, SLABS, AND BLOCKS Editing 3D Polygons and Slabs With the Partial menu options, you can edit - move, add, or delete vertices in - a polygon or slab. You can also toggle the edges of a polygon or slab to visible or invisible. To maintain its integrity, edit the polygon or slab in the same plane in which it was created or at least in a plane parallel to the polygon or slab. Use PlneSnap, NewElev, or EditPlne from the 3DViews menu. See the chapter on Viewing Your Model for more information about the options for PlneSnap, NewElev, and EditPlne in the 3Dviews menu. To simulate polygons or slabs with more than 36 sides, you can create a 36-sided polygon or slab and mark one of the edges as invisible. You can connect another polygon or slab with a shared invisible edge to the first invisible edge. By hiding the seams, you can build a patchwork of polygons or slabs that simulates a polygon or slab of an unlimited number of sides. To add vertices to a polygon or slab: 1. Choose AddVrtex from the Partial menu. Make sure that the current editing plane is parallel to the polygon or slab you want to edit. Warning: Use caution with MovVrtex and AddVrtex. These commands can create physically impossible shapes. The most common problems include letting edges cross over one another and pulling vertices out of the plane of the polygon or slab, thus creating a twisted and ambiguous shape. 2. Select the edge of the polygon or slab to which you want to add a vertex. Remember that a polygon or slab can have no more than 36 vertices. Notice that this edge of the polygon or slab becomes a rubberband line with your cursor attached to the edge. 3. Position the new vertex. Add Here Before After Figure 21.11: Adding a vertex To delete the vertices of a polygon or slab: 1. Choose DelVrtex from the Partial menu.

13 EDITING 3D POLYGONS AND SLABS Select the vertex you want to delete. The vertex disappears and the two edges that led into the deleted vertex now become a single edge. Because a polygon or slab can have no less than three vertices, you cannot delete a vertex from a triangular-shaped polygon or slab. Delete Be fore After Figure 21.12: Deleting a vertex To reposition the vertex of a polygon or slab: 1. Choose MovVrtex from the Partial menu. Make sure that your current editing plane is parallel to the polygon or slab that you want to edit. 2. Select the vertex you want to move. Notice that this vertex is now attached to your cursor and the two edges of the polygon or slab that lead to this vertex become rubberband lines. You can also move a vertex with the Stretch option in the 3DEdit menu. 3. Select a new vertex position. Moved Be fore Figure 21.13: Moving a vertex After Use the MarkVis toggle to change the visibility of individual edges of a polygon or slab. Selecting a visible edge makes it invisible, while selecting an invisible edge makes it visible. Edges made invisible are not erased; they are suppressed from view, usually to hide the seams between adjacent polygons or slabs. Invisible edges remain invisible after hidden line removal, but the polygon or slab is processed as if they were visible; invisible edges can obscure objects that lie behind them.

14 418 CHAPTER 21: MODELING WITH 3D POLYGONS, SLABS, AND BLOCKS To make an edge visible or invisible: 1. Choose MarkVis from the Partial menu. 2. Select the edge of the polygon or slab you want invisible. Figure 21.14: Using MarkVis on one edge To make all edges visible: 1. Choose MarkAll from the Partial menu. 2. Select the polygon or slab that you want visible. The edges of the selected polygon or slab become visible. To make all edges invisible: 1. Choose UnMrkAll from the Partial menu. 2. Select the polygon or slab that you want invisible. The edges of the selected polygon or slab become invisible. Making a polygon or slab completely invisible with UnMrkAll has obvious problems. The best way to recover an invisible polygon or slab is to use Area or Fence from the selection menu with MarkAll in the region where you think the polygon or slab exists. Drawing Blocks A block is a simple solid with six rectangular or parallelogram-shaped faces. Because the top of a block is not constrained to lie directly over its bottom, blocks are particularly useful for modeling supporting members that lean to one side. To draw blocks: 1. Choose Block from the 3D Entity menu. 2. Select the shape of the base of the block: for a rectangular base, choose RectAngl; for a parallelogram base, choose Parallel. 3. Choose AutoHgt to automatically place the vertex at Z-height, centered over the center point of the base; otherwise, you must place the vertex manually. 4. Choose to place the reference face of the block with one of the following: Base+Thk At Z-base, extending up through a distance equal to the thickness parameter set below

15 Hgt+Thk DRAWING BLOCKS 419 At Z-height, extending up through a distance equal to the thickness parameter set below Base/Hgt At Z-base, extending up to Z-height If you choose Base+Thk or Hgt+Thk, you can use Thicknss to set the thickness of the block. (Otherwise, the Thicknss setting is ignored.) As with all Z measurements, a positive thickness extends out of the screen, and a negative thickness extends into the screen. Choose Thicknss from the Blocks menu, and then choose or type a value and press (Enter). 5. Continue with the sections below for either rectangular-based blocks or parallelogram-based blocks. To draw rectangular-based blocks: 1. Select the first corner of the block base. 2. Move the mouse diagonally, expanding the base of the block to the proper size. Select the second corner of the block base. If you selected AutoHgt, DataCAD places the top of the block directly over the bottom and the block is finished. 3. Turn AutoHgt off and select a location of the top of the block; the sides of the block are drawn, connecting the top and bottom faces. Figure 21.15: Rectangular-based blocks To draw parallelogram-based blocks: 1. Select a point to serve as one corner of the block. 2. Select a second corner that, along with the first point, forms an edge for the base of the block. 3. Select a third corner point to form the parallelogram base of the block. Notice how opposite sides of the base remain parallel but are not constrained to right angles. When you select AutoHgt, DataCAD places the top of the block directly over the bottom and the block is finished. 4. Turn AutoHgt off and select a location of the top of the block; the sides of the block lean to connect the top and bottom faces.

16 420 CHAPTER 21: MODELING WITH 3D POLYGONS, SLABS, AND BLOCKS