4.2.1 WalkTut Tutorial

This is a tutorial to show how you can use Crystal Entity Layer in your own applications.

The source files of this tutorial can be found in the ‘apps/tutorial/walktut’ directory that is included with CEL. The world and entity file can be found in the ‘data’ directory (‘walktut_world’ and ‘walktut_entities’).

Remember that the first time you run this application you have to add the ‘-relight’ commandline option so that the lightmaps are correctly updated.

During the game you can use the following inputs:

• ‘arrow keys’: movement.
• ‘m’: camera mode (first person, third person, ...).
• ‘left mouse button’: pick up an item and put in inventory.
• ‘d’: drop the last item picked up.

This tutorial features:

• Camera handling using the ‘pccamera.old’ property class.
• Movement of an actor in a game using the ‘pcmove.linear’ property class.
• Visualization of the player using the ‘pcobject.mesh’ property class.
• Handling of the player inventory using the ‘pctools.inventory’ property class.
• Handling of keyboard and mouse input using the ‘pcinput.standard’ property class.
• Loading world and entity file using the ‘pcworld.zonemanager’ property class.
• Usage of the ‘celentity’ addon to add entities from an XML map file.
• How to create behaviours in C++ for game logic.

Here is the tutorial:

The XML Entity File

Except for the level and player entities all other entities are defined in the ‘entities’ file. Here is an example of how such an entity looks:

    <addon plugin="celentity" entityname="badone">

      <propclass name="pcobject.mesh">
        <action name="LoadMeshPath">
	  <par name="path" string="/this/model" />
	  <par name="filename" string="monkey" />
	  <par name="factoryname" string="monkey" />
	</action>
      </propclass>

      <propclass name="pcobject.mesh.select" />

      <propclass name="pctools.properties">
        <property name="pos1" vector="9,2,8" />
        <property name="pos2" vector="6,2,8" />
        <property name="pos3" vector="6,2,12" />
        <property name="pos4" vector="7,5,10" />
        <property name="pos5" vector="8,1,7" />
        <property name="pos6" vector="9,2,8" />
        <property name="up1" vector="0,1,0" />
        <property name="up2" vector="0,1,0" />
        <property name="up3" vector="0,1,0" />
        <property name="up4" vector="0,1,0" />
        <property name="up5" vector="0,1,0" />
        <property name="up6" vector="0,1,0" />
        <property name="forward1" vector="-1,0,0" />
        <property name="forward2" vector="0,0,1" />
        <property name="forward3" vector="1,1,-1" />
        <property name="forward4" vector="1,-1,-1" />
        <property name="forward5" vector="1,1,1" />
        <property name="forward6" vector="-1,0,0" />
        <property name="time1" long="1000" />
        <property name="time2" long="1000" />
        <property name="time3" long="1000" />
        <property name="time4" long="1000" />
        <property name="time5" long="1000" />
        <property name="time6" long="1000" />
      </propclass>

      <propclass name="pctools.timer">
        <action name="WakeUp">
	  <par name="time" long="5000" />
	  <par name="repeat" bool="true" />
	</action>
      </propclass>

      <propclass name="pcmove.linear">
        <action name="InitCD">
	  <par name="body" vector=".2,.2,.2" />
	  <par name="legs" vector=".2,.2,.2" />
	  <par name="offset" vector="0,-.3,0" />
	</action>
        <action name="SetPosition">
	  <par name="position" vector="9,3,8" />
	  <par name="sector" string="Scene" />
	  <par name="yrot" float="0" />
	</action>
      </propclass>

      <behaviour name="badone_behave" />

    </addon>

In this particular example we use the ‘cel.addons.celentity’ addon (see section CelEntity Addon) to create an entity with the name ‘badone’. It has the following property classes:

• ‘pcobject.mesh’ (see section Mesh). This mesh is setup with the ‘monkey’ model that was made in ‘Blender’.
• ‘pcobject.mesh.select’ Used for selection of mesh.
• ‘pctools.properties’ This is a generic property class for storing named properties. In this particular case the ‘badone_behave’ behaviour will read out the properties to construct the path for the catmull rom spline.
• ‘pctools.timer’ (see section Timer). This timer will be used to restart the movement along the path after 5 seconds (5000 milliseconds).
• ‘pcmove.linear’ (see section Linear Movement). This is the generic movement system.

We also create the entity with the ‘badone_behave’ behaviour.

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