It is very important that you understand how mouse input is mapped to 3D coordinates when editing objects in TrenchBroom. Since the mouse is a 2D input device, you cannot directly control all three dimensions when you edit objects with the mouse. For example, if you want to move a brush around, you can only move it in two directions by dragging it. Because of this, TrenchBroom maps all mouse input to the horizontal XY plane. This means that you can only move things around horizontally by default. To move an object vertically (and left or right), you need to hold the option key (⌥) during editing.
Sometimes, the effect of an editing action depends on the camera direction. Consider the axis of the rotation commands for example. Depending on how the camera is oriented, one of the coordinate system axes is selected as the rotation axis for these commands. To explain how such commands work, we will use the concept of the closest axis of a vector. For any given vector, its closest axis is determined by its greatest absolute component. So, if the camera direction is (0.7, 0.6, -0.4), the closest axis is the positive X axis because the X component (0.7) is the absolute greatest component of that vector.
You can either move objects using the cursor keys or the mouse. The ← and → cursor keys move the selected objects left or right on the editing plane whereas the ↓ and ↑ keys move them towards or away from the camera. To move objects vertically, use the page up (⇞) or page down (⇟) key.
To move the selected objects horizontally using the mouse, click and drag the objects with the left mouse button. To move them vertically, hold the option key (⌥) while dragging.
If grid snapping is enabled, the bounding box of the selected objects is snapped to the grid. This is most easily explained with the above screenshots. The bounding box of the object in the left screenshot is obviously not aligned to the grid because the object is smaller than the grid. If this object is moved to the right, it is not moved by the actual grid size. Instead it is moved so that the right side of the bounding box is aligned to the grid. This can be seen in the right screenshot. If you move this object to the right again, it is moved by the grid size because the right side of the bounding box was already aligned to the grid.
There are two options for rotating objects. The first is to rotate the selected brushes by 90° about the one of the axes of the coordinate system. The second is to rotate the selected objects freely using the mouse. In both cases, the center of the rotation is the center of the selected objects' bounding box.
To rotate the selected objects by 90° clockwise about one of the axes of the coordinate system, choose one of the rotation commands from the Edit » Actions menu or hit the appropriate keyboard shortcut. The following rotation commands are available:
Objects can also be rotated freely without any restriction as to the angle or axis of the rotation. To rotate the selected objects, hold the option and command keys (⌥⌘) and move your mouse in the 3D view. You will see that the mouse cursor turns into a rotation cursor that indicates the axes about which the objects can be rotated using the mouse. While the horizontal rotation axis is always the Z axis, you can adjust the vertical rotation axis by moving the mouse left and right. The current rotation axes are represented by a compass-like figure (see screenshot below).
To start the rotation, click and drag the left mouse button. If you move the mouse left and right, the objects are rotated about the Z axis and if you move your mouse up and down, they are moved about the selected vertical rotation axis. The current vertical rotation axis depends on the horizontal rotation you have already applied. Note that the rotation angle is constrained to 15° increments if grid snap is enabled. Disable grid snap to rotate the selected objects without any constraints.
The selected objects can be flipped (or mirrored) along the horizontal axis of the editing plane by choosing Edit » Object » Flip Horizontally from the menu or hitting ⌘F. To flip the selected objects along the vertical axis of the editing plane, hold the option key (⌥) when invoking the flip command.
To delete brushes or entities, select them in the 3D view and hit the backspace key (⌫). Note that you an also delete faces of brushes under certain circumstances.
You can assign new textures to faces in two ways: Selecting the texture for the currently selected faces in the texture browser or using the mouse. To assign a texture using the first way, select the faces you want to assign the texture to in the 3D view and then click on the texture in the texture browser. If you select entire brushes in the 3D view, the texture will be assigned to all faces of the selected brushes.
The second way is useful if you want to copy the texture of an existing face to other faces. First, select the face whose texture you want to copy in the 3D view. This face is called the source face. Then left click on the target faces you wish to copy the texture to while holding the option key (⌥). If you double click while holding the option key, the texture is applied on each face of the brush to which the target face belongs.
In the next section, you will learn how you can use this technique to not only copy the texture and the attributes of an existing face to other faces.
The attributes of a face are the horizontal and vertical offsets and scaling factors as well as the rotation of the texture. To examine the attributes of a face, you must first select it in the 3D view. The quick view bar at the bottom of the 3D view displays the attributes of the selected face(s) in its very right section:
The other way to inspect the attributes of the selected face(s) is to switch to the Face tab of the inspector. Here, you can also manipuate the attributes by entering new values or by using the small up / down buttons next to the text fields.
The second way to manipulate the attributes of the selected face(s) is to use the appropriate menu commands in the Edit menu, the Edit » Texture submenu or their respective keyboard shortcuts. The following list details each of the commands:
To move the texture by 1 instead of the current grid size or to rotate the texture by 1° instead of 15°, hold the option key (⌥) while invoking these commands.
Besides copying the texture of the selected face to other faces, you can also use the mouse to copy face attributes. Simply hold the command key (⌘) while clicking on another face and along with the texture, the attributes of the source face are copied to the target face you clicked on.
Each Quake entity has some properties associated with it. These properties control the appearance or the effect of an entity in the game. Each property has a key and a value. In TrenchBroom, these properties can be edited using property list in the entity inspector. The property list represents all properties of the selected entities.
To edit the key or the value of a property, simply double click it and enter the new key or value in the entity inspector. Hit return (↩) to commit the changes. To create a new property, click on the plus button below the property list. To delete one or more properties, select them in the list and click on the minus button below the property list. Note that you can also edit the properties of multiple selected entities at once. However, only those properties are displayed in the list which all selected entities have in common.