Creating a House
Level: Beginner
Goal: Learn basic skills for PEP modeling (editing points,
edges, and polygons). Also learn how to change the appearance of a
model by coloring vertices and specifying backface culling.
Assumptions: You should be familiar with the concept of PEP
modeling. See PEP Modeling: Editing
Points, Edges, and Polygons in the online help for more details.
You should also be familiar with the Cosmo Worlds user interface. See A Quick Look at the User Interface for
more details.
Finished product:

This tutorial consists of the following sections:
Use Undo and Redo to fix mistakes:
-
Undo = Ctrl+Z
-
Redo = Shift+Ctrl+Z
The basic shape for a house is fairly simple.
-
Start out with a cube in the PEP editor. Switch to hidden line so you
can see the individual polygons easily (press and hold the right mouse
button over your workarea and choose Draw Style > Hidden Line
from the popup menu).
-
Select the top polygon and press
to split the top polygon
lengthwise.

-
Select the edge in the middle of the split polygon and Shift-drag
along a side polygon to push the edge up and form the roof:
Use Split Buttons to Define the Dormer
You can model interesting shapes from a simple PEP object like a square
by using a combination of split and cut operations, then extruding and
moving the new polygons. Here's how to create a dormer from the basic
house shape.
-
Starting with the basic house shape in Example 1, select a side of the
roof and press
to split
the polygon lengthwise:

-
Select the lower half of the roof and press
to split the polygon
vertically:

-
Keeping the same selection from step 2 (don't select anything new),
press
to split the quads like
this:

-
To make the angles for the dormer roof, select the appropriate quad and
press
or
:

Now you have the basic shape for the dormer.
Extrude, Rotate, and Pull Out the Dormer
-
To pull out the dormer, Shift-click to select the four
polygons that make up the dormer. The last polygon you click becomes
the master selection and is outlined in black:

The master selection is used for aligning the front face of the dormer
to the front face of the house. If you lose the master selection in
later steps, you can reselect it by Shift-clicking the
polygon twice--the first time deselects the polygon and the second time
adds it to the selection and specifies it as the master selection.
-
Move the dormer up and away from the rest of the roof. Make sure you
have the correct polygons selected as described in step 1. Then press
the Extrude Polygons button
.
Place the mouse cursor over the dormer and Ctrl-drag out, so
the dormer moves away from the house and its edges are perpendicular to
the roof.

Next you want the dormer's face parallel to the front of the house. To
fix the angle, you'll use the Snap Target and PEP Jack.
-
Place the Snap Target by placing the mouse cursor on the front of the
house and clicking the middle mouse button. A yellow arrow appears (see
image in step 4). The target is used to align the master selection
(specified in step 1) to the front of the house.
-
Click the PEP Jack button
and
place the tool by clicking in the scene. Position the tool by dragging
it. The PEP Jack doesn't need to be on the master selection or near it,
but it does need to be positioned so the ring and green balls are in
the same plane as the side of the house (see image below).

-
Make sure the dormer polygons are selected and the master selection is
specified (see step 1). Rotate the PEP Jack by dragging a green knob.
The PEP Jack pulls the dormer face down. Drag the PEP Jack until the
front of the dormer is parallel to the front of the house. Dotted lines
indicate the master selection's alignment relative to the Snap Target;
use this feedback to help you position the dormer correctly.
-
Before the dormer is complete, you need to move it up so that it looks
right. First, make sure the polygons making up the dormer are selected.
Position your cursor over the front of the house, and Shift-drag
up to move the dormer so that the bottom edges are aligned with the top
edge of the polygon making up the front of the house. Again, use the
feedback from the Snap Target to help you position the dormer
correctly. Starbursts appear along the master selection to indicate its
alignment.
-
Take a moment to clean up your workarea; put away the PEP Jack
and the Snap Target
by clicking their buttons on the
PEP and Layout palettes.
Now that the dormer is correct, you want to create a door for the
house.
-
Click the Cut Rectangle button
(on the PEP palette) and drag
the cutting tool across the front of the house to define a new polygon
for the door:

-
If you try to select and move this polygon, it will pull out the points
that define the front of the house. To move just the polygon that
defines the door, select it and click the Chip Off Polygon button
.
-
The result is a polygon you can move independent from the rest of the
house.
-
Next, rotate the edge of the door like a hinge. Place the PEP Jack
in the scene and align it along the
edge of the door as shown below:

Make sure the polygon making up the door is selected, then drag a
green knob on the PEP Jack to rotate the door open.
To color the house, use the Color Per Vertex Editor. This editor is
pretty easy to use (for the basics, see the Color Per Vertex Editor quick
reference). However, there's a trick to get the color of the roof
separate from the rest of the house. Right now, each roof's side is
made up of a single polygon that makes up the whole side of the house.
When you try to color the roof, here's what happens:

Note: This image shows part of the Color Per Vertex editor next
to the workarea. The model in the workarea is shown in Hidden Line draw
style.
To color just the bottom square making up the side of the house, you
first need to define the side polygon as two separate polygons. Click
the Cut Polygon button
on the Split
palette. Click to define the first endpoint for the new edge and drag
out a line, releasing the mouse button where you want to create the
second endpoint. You now have a new edge that separates the side
polygon into two polygons, separating the roof from the rest of the
side of the house. Repeat this process to separate the roof on the
other side of the house. When you color a side of the house, it should
now look like this:

Now that your house is colored, switch from Hidden Line draw style to
As Is. (Choose Draw Style > As Is from the right mouse popup
menu.) Notice that when you look inside your house, you can't see the
inside of the walls or floor. To fix this, open the Normal Doctor and
deselect the box next to Cull Backfacing Triangles.
-
Select the house (you should not be in PEP Editing mode).

-
Click the Normal Doctor button on the Looks palette:

-
Click the box next to Cull Backfacing Triangles to remove the
checkmark.
Now you can see the walls and floor inside the house.

That's it! For more information on any of these topics or tools, refer
to the appropriate section in the online help.