3D Game Programming All In One (2004)

588 Chapter 21 ■ Creating the Game Mission

Table 21.1 File Menu Commands

Command	Description
New Mission	Creates a new empty mission with a default terrain and sky.
Open Mission	Opens an existing mission for editing.
Save Mission	Saves changes to the current mission to disk.
Save Mission As	Saves the current mission under a new name.
Import Terraform Data	Imports terraform rules from an existing terrain file.
Import Texture Data	Imports terrain texture rules from an existing terrain file.
Export Terraform Bitmap	(Only active from the Terrain Terraform Editor.) Exports the current
	terraform map to a bitmap.

As is standard with windowed applications these days, there is an Edit menu that houses a variety of object and item editing commands. As you can see in Table 21.2, in addition to the ubiquitous Cut, Copy, and Paste functions, there are also commands that are used to access various settings for the editors.

Table 21.2 Edit Menu

Menu Item	Description
Undo	Undoes the last action in terrain or world editing. Not all actions can be
	undone.
Redo	Redoes the last undone action.
Cut	Cuts the selected objects in the World Editor from the mission to the
	Clipboard.
Copy	Copies the selected objects in the World Editor to the Clipboard.
Paste	Pastes the current clipboard contents into the mission.
Select All	Selects all mission objects in the World Editor.
Select None	Clears the current selection in the World and Terrain Editors.
Relight Scene	Recomputes the mission's static lighting and applies it.
World Editor Settings	Accesses the settings dialog box for the World Editor.
Terrain Editor Settings	Accesses the settings dialog box for the Terrain Editor.

Use the Camera menu, as described in Table 21.3, to change camera modes and adjust the camera fly mode speed.

The World menu is available by default and contains functions related to the World Editor—its capabilities will be described in the "World Editor" section, which is coming up next.

The Window menu is pretty straightforward, so it doesn't require a table to describe its functions. It is used to invoke each of the available subeditors.

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Table 21.3 Camera Menu

Menu Item	Description
Drop Camera At Player	Moves the camera object to the location of the player, and sets the mode
	to camera movement mode (camera fly mode).
Drop Player At Camera	Moves the player object to the location of the movable camera, and sets
	the mode to player movement mode (player mode).
Toggle Camera	Toggles between player and camera fly movement modes. Your view will
	also switch to the location of either the player or the camera, depending
	on the mode.
Slowest to Fastest	Adjusts the movement speed of the camera fly mode.

World Editor

The World Editor provides a view of the 3D world. Objects in this view, like structures, interiors, shapes, and markers, can be manipulated with either the mouse or the keyboard.

There are three frames in the view: the World Editor Tree, the World Editor Inspector, and the World Editor Creator.

World Editor Tree

The World Editor Tree view is displayed in the frame in the upper-right screen corner in both the World Editor Inspector and the World Editor Creator. This tree displays the hierarchy of the mission data file. Objects selected in the Tree view will also be selected in the main view. Objects in the Tree view can be organized into groups.

There is a special group selection called the Instant Group, which is displayed with gray highlighting in the Tree view. This is the group in the Tree view where newly created or pasted objects are placed. Objects created from the World Editor Creator are also placed in the Instant Group. To change the current Instant Group, Alt+Click on a group in the Tree view.

World Editor Inspector

The World Editor Inspector lets you examine and specify properties of mission objects. When you select an object in Inspector mode, that object's properties are displayed in the frame at the lower right of the screen. After editing an object's properties, click the Apply button to commit those properties to the object. Dynamic properties can be assigned to objects with the Dynamic Fields Add button. Dynamic fields can be accessed via the scripting language and are normally used to add game-specific properties to objects.

World Editor Creator

The World Editor Creator displays an extra Tree view frame in the lower-right corner of the screen. This view contains all objects that can be created in a mission. Selecting an

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590Chapter 21 ■ Creating the Game Mission

object from this list creates a new instance of it and drops the new object at the center of the screen (by default) or as specified by the selected Drop at command in the World menu, which is shown in Table 21.4.

Table 21.4 World Menu

Menu Item	Description
Lock Selection	Locks the current selection so that it cannot be manipulated from the World
	Editor view.
Unlock Selection	Unlocks a locked selection.
Hide Selection	Hides the current selection to help reduce visual clutter.
Show Selection	Unhides hidden objects in the selection.
Delete Selection	Deletes the currently selected objects.
Camera To Selection	Moves the camera to the selected objects.
Reset Transforms	Resets the rotation and scale on the selected objects.
Drop Selection	Drops the selected objects into the mission according to the drop rule (see Drop
	Selection menu items that follow). If the object is already placed, it is picked up
	and dropped again.
	Drop at Origin: Drops newly created objects at the origin.
	Drop at Camera: Drops newly created objects at the camera's location.
	Drop at Camera w/ Rot: Drops newly created objects at the camera's
	location with the camera's current orientation.
	Drop below Camera: Drops newly created objects below the camera's
	current location.
	Drop at Screen Center: Drops newly created objects where the view
	direction hits an object.
	Drop at Centroid: Drops newly created objects at the center of the
	selection.
	Drop to Ground: Drops newly created objects to the terrain ground level
	at their current location.

You can use both the mouse and the keyboard for editing, as shown in Table 21.5.

Gizmos are the visual representation of each object's three axes. When you select an object, and if you have gizmos enabled in the World Editor Settings dialog box, then they will appear centered on that object's local origin.

If gizmos are enabled, they can be clicked and dragged (as described in Table 21.6) in order to modify the object to which they are attached.

Terrain Editor

We use the Terrain Editor to manually modify the terrain height map and square properties by using a mouse-operated brush. The brush is a selection of terrain points or squares

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Table 21.5 Mouse and Keyboard Operations

Operation	Description
Clicking on an unselected object	Deselects all currently selected objects and selects the clicked
	object.
Clicking in empty space	Click-drags a box around objects, and selects all objects in the
	box.
Shift-clicking on an object	Toggles selection of the clicked object.
Mouse dragging a selected object	Moves the selected objects, either on a horizontal plane or
	sticking to the terrain, depending on the setting of the Planar
	Movement check box in the World Editor Settings dialog box.

Control-clicking and drag Alt-clicking and drag Alt-Ctrl-clicking and drag

Moves the selected objects vertically.

Rotates the selected objects about the vertical axis. Scales the selected object by a face on the bounding box.

	Table 21.6	Gizmo Operations
	Operation	Description
	Click-drag gizmo axis		Moves selection along the selected axis.
	Alt-click-drag gizmo axis		Rotates selection on the selected axis.
	Alt-Ctrl-click-drag gizmo axis		Scales along the selected axis.

centered around the mouse cursor. Table 21.7 describes the functions available in the Brush menu.

Table 21.7 Terrain Editor: Brush Menu

Menu Item	Description
Box Brush	Uses a square-shaped brush.
Circle Brush	Uses a circular brush.
Soft Brush	Sets the brush so that its influence on the terrain diminishes toward the
	edges of the brush. The brush square colors vary from red, where the
	influence is greatest, to green, where the influence is least. The Terrain
	Editor Settings dialog box Filter view has controls that adjust the falloff.
Hard Brush	Sets the brush so that the effect on the terrain is the same across the
	surface of the brush. All squares in the brush are the same red color.
Size 1 1 to 25 25	Sets the brush sizes.

When we use the Terrain Editor, we modify the terrain as if we were piling dirt onto it or shoveling holes into the ground. Table 21.8 shows the operations available in the Terrain Editor via the Action menu.

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Table 21.8 Terrain Editor: Action Menu

Menu Item	Description
Select	Moves the brush in a painting motion to select grid points.
Adjust Selection	Raises or lowers the terrain at the currently selected grid points as a group by
	dragging the mouse up or down.
Add Dirt	Adds terrain "dirt" to the terrain at the center of the brush, raising the affected
	terrain area.
Excavate	Removes dirt from the center of the brush.
Adjust Height	Raises or lowers the area marked by the brush by dragging the mouse.
Flatten	Sets the area marked by the brush to a flat plane height.
Smooth	Smoothes the area marked by the brush—peaks are lowered and troughs are
	raised.
Set Height	Sets the area marked by the brush to a constant height—the height is set using
	the Terrain Editor Settings.
Set Empty	Makes a hole in the terrain in the squares covered by the brush.
Clear Empty	Fills in any holes in the squares covered by the brush.
Paint Material	Paints the current terrain texture material with the brush.

Terrain Terraform Editor

The Terrain Terraform Editor uses mathematical algorithms to generate terrain heightfields (height maps). Heightfield operations are arranged in a stack, which is an ordered list of operations. Operations in the stack depend on the results of previous operations to produce new heightfields. The results of the final operation on the stack can be applied to the terrain using the Apply button.

There are two Terrain Terraform Editor frames. The top frame displays information about the currently selected operation, and the bottom frame shows the current operation stack. Between them is a pull-down menu for the creation of new operations. The first operation in the stack is always the General operation, which can't be deleted.

Table 21.9 shows the operations available.

Terrain Texture Editor

The Terrain Texture Editor uses mathematical techniques to place terrain textures based on the heightfield at the bottom of the terraformer heightfield stack. The editor has three main interface elements on the right side of the screen. From top to bottom they are the operation Inspector frame, the Material list, and the Placement Operation list.

Terrain materials are textures that are added using the Add Material button. This will look for any texture (.png or .jpg) in a subdirectory of any directory named "terrains" (in this book, this also applies to a directory name maps). Once a material is added to the terrain,

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Table 21.9 Terraform Operations

Operation	Description
fBm Fractal	Creates bumpy hills.
Rigid Multifractal	Creates ridges and sweeping valleys.
Canyon Fractal	Creates vertical canyon ridges.
Sinus	Creates overlapping sine wave patterns with different frequencies useful
	for making rolling hills.
Bitmap	Imports an existing 256 by 256 bitmap as a heightfield.
Turbulence	Jumbles the effects of another operation on the stack.
Smoothing	Smoothes the effects of another operation on the stack.
Smooth Water	Smoothes water.
Smooth Ridges/Valleys	Smoothes an existing operation on edge boundaries.
Filter	Applies a filter to an existing operation based on a curve.
Thermal Erosion	Applies an erosion effect to an existing operation using a thermal erosion
	algorithm.
Hydraulic Erosion	Applies an erosion effect to an existing operation using a hydraulic erosion
	algorithm.
Blend	Blends two existing operations according to a scale factor and a
	mathematical operator.
Terrain File	Loads an existing terrain file onto the stack.

the user can select one of several placement operations that govern where that material will be placed on the terrain. They are shown in Table 21.10.

Table 21.10 Terrain Texture Editor Placement Operations

Operation Description

Place by Fractal

Place by Height Place by Slope Place by Water Level

Places the terrain texture randomly across the terrain based on a Brownian motion fractal operation.

Places the texture based on an elevation filter. Places the texture based on a slope filter.

Places the texture based on the water level parameter in the Terraform Editor.

Click the Apply button to commit the current texture operation list to the terrain file.

Mission Area Editor

The Mission Area Editor defines regions in the game that are used to constrain player travel. If we use mission areas in a game, we normally give warnings or disqualifications if a player leaves a mission area. Of course, you can probably find other uses for such a feature.

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The Mission Area Editor displays an overhead height-map view of the current mission map in the upper-right corner of the screen. There are markers for mission objects, a box for the mission area, and a pair of lines denoting the current field of view. Clicking anywhere on the display will move the current view object (either camera or player) to that location in the mission.

To edit the mission area, select the Edit Area check box. This will display eight resizing knobs on the mission area box that can be dragged with the mouse.

Clicking the Center button will cause the terrain file data to be repositioned and centered at 0,0 in the center of the mission area box.

To mirror the terrain, click the Mirror button. This will put the Mission Area Editor in mirror mode. The Left and Right Arrow buttons adjust the mirror plane angle to one of eight different angles (two axis aligned, two 45-degree splits). Click the Apply button to commit the terrain mirroring across the mirror plane. Mirroring a mission area is a useful way to quickly create terrain for team-based games where each side would begin with identical terrain. This would stop either side from having a terrain advantage. You create the terrain for one side, and then simply mirror it for the other side.

Building the World

Let's get to work building the game world, and let's start with items 27 and 28 from our requirements list. I've chosen the fire and the waterfall to start with here because we haven't really looked at particles much yet, and with particles we get to touch on various topics we've covered in this chapter, like easing into using the Mission Editor, the World Editor Creator, and the World Editor Inspector. And besides that, particles are cool.

Particles

Remember the raindrops in Chapter 18? Those were particles. Particles are basically sin- gle-faced polygons that are generated in bulk by a game engine to simulate a variety of somewhat related real-world phenomena, such as rain, smoke, wispy fog, splashing and spraying water or mud, fire, and flames. Particles can be used to simulate any sort of constantly changing fluidor gaslike entity. Even a swarm of mosquitoes can be generated using particles.

What I'll do in this section is show you how to use the Torque particle system to make a campfire and a waterfall.

Particles are made of three parts:

■Particle. The actual things we see.

■Particle Emitter. The thing that causes the particles to come into existence.

■Particle Emitter Node. The object that the emitter is attached to.

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If you attach the word data to the end of each, and remove the spaces, you'll have the formal names of the datablocks that define those terms of the particle system:

ParticleData

ParticleEmitterData

ParticleEmitterNodeData

Particles can live in the game world in one of two ways: as freestanding particles or as attached particles. Freestanding particles are defined using all three of the datablocks just mentioned, while attached particles only require defining the ParticleData and the ParticleEmitterData. The nodes aren't needed, because we are attaching the particle to some other object that supports particles. The object classes that support particles are players, weapons, projectiles, and all vehicle types. As noted already, Rain is a specialized object that has a built-in particle capability.

So in the case of freestanding particle emitters, one more definition of interest is required for placing emitters in the world:

ParticleEmitterNode

We'll look at freestanding particle emitters a bit more, shortly.

Campfire

To make a campfire, we'll need two particle definitions: one for the flames and one for the smoke. The particle types used will be freestanding, so we will need to define all three particle datablocks for both the smoke and the flames.

First, copy the image file C:\3DGPAi1\RESOURCES\CH21\flame.png to C:\koob\control\ data\particles.

Next, create the file C:\koob\control\server\misc\particles.cs and add the following code to it:

datablock ParticleData(Campfire)

{

textureName	= "~/data/particles/flame";
dragCoefficient	= 0.0;
gravityCoefficient	= -0.35;
inheritedVelFactor	= 0.00;
lifetimeMS	= 580;
lifetimeVarianceMS	= 150;
useInvAlpha = false;

spinRandomMin = -15.0; spinRandomMax = 15.0;

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	colors[0]	= "0.8 0.6 0.0 0.1";
	colors[1]	= "0.8 0.65 0.0 0.1";
	colors[2]	= "0.0 0.0 0.0 0.0";
	sizes[0]	= 1.0;
	sizes[1]	= 2.0;
	sizes[2]	= 4.0;
	times[0]	= 0.1;
	times[1]	= 0.4;
	times[2]	= 1.0;
	};

datablock ParticleEmitterData(CampfireEmitter)

{

ejectionPeriodMS = 15; periodVarianceMS = 5;

ejectionVelocity = 0.35; velocityVariance = 0.20;

thetaMin	=	0.0;
thetaMax	=	60.0;

particles = "Campfire" TAB "Campfire";

};

datablock ParticleEmitterNodeData(CampfireEmitterNode)

{

timeMultiple = 1;

};

Now open C:\koob\control\server\server.cs, locate the function OnServerCreated, and add the following line to the end of the function, before the closing brace ("}"):

exec("./misc/particles.cs");

Now, open your mission file (C:\koob\control\data\maps\koobA.mis or whatever your mission file is called, as long as it is the same as the one used for Chapter 6 and uses the same terrain) and add the following before the closing brace of the file:

new ParticleEmitterNode() {

position = "13.2665 -2.0218 196.6";

rotation = "1 0 0 0";

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scale = "1 1 1";

dataBlock = "CampfireEmitterNode";

emitter = "CampfireEmitter";

velocity = "1";

};

Okay, save your files, and then launch Koob. When your player spawns in, turn to the right—you should see a little fire burning in the gully there, as shown in Figure 21.1.

The flame is the glowing object to the left of the crosshair in the picture. Now let's add the smoke. We'll do it slightly differently. We begin by defining the particle and emitter as before, but then we'll place it in an easier way

using the World Editor.

Figure 21.1 Campfire.

Open up the particles.cs file you created earlier, and add the following:

datablock ParticleData(CampfireSmoke)

{

textureName	= "~/data/particles/smoke";
dragCoefficient	= 0.0;
gravityCoefficient	= -0.15;
inheritedVelFactor	= 0.00;
lifetimeMS	= 4000;
lifetimeVarianceMS	= 500;

useInvAlpha = false; spinRandomMin = -30.0; spinRandomMax = 30.0;

colors[0]	= "0.5 0.5 0.5 0.1";
colors[1]	= "0.6 0.6 0.6 0.1";
colors[2]	= "0.6 0.6 0.6 0.0";
sizes[0]	= 0.5;
sizes[1]	= 0.75;
sizes[2]	= 1.5;
times[0]	= 0.0;
times[1]	= 0.5;
times[2]	= 1.0;

};

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