© 2008—2009 Graybox Games
Development of
Early Stage Testing
Path following and proximity detection.  In this early experiment, robot boxes follow a track that is defined by the spheres located at each of the turns.  Additionally, towers detect and track the progress of the robots.  The upper tower indicates its target by a green straight line, while the lower tower shows a curved line that indicates the trail of a self-guided projectile used for attacking the target.  Trigger colliders, shown here as translucent spheres, are used by each tower to detect and subsequently select an enemy robot within its range.
Instead of one path, now there are three.  In this image we see that multiple robot boxes can be detected and tracked simultaneously.  Multiple towers independently attack with either line-of-sight shots or guided projectiles.
Grid selection for building towers.  Aside from tilting the maze to form an angle with the camera, we see that two of the grid squares are now highlighted.  The dark green square is the currently selected square and the middle square with a mouse cursor hovering over it is the currently highlighted square.  The latter will become the selected square when the mouse button is pressed.
A Note About Lighting
The surface should be covered with pyramid structures, but they disappeared.  Maybe this doesn't come as a surprise to everyone, but when we use "auto" mode on the lights, the details of a mesh may become invisible.  In this case a spotlight was placed in the upper righthand corner of the maze in auto mode. Since the light is close to the mesh it is operating as a pixel light.
Vertex mode reveals the detailed mesh.  The spotlight was moved further away from the mesh and automatically switched to a vertex light.  The surface detail of the mesh that was previously invisible now becomes visible.
Moving the spotlight further away.  The spotlight was moved further above the mesh and the surface structure now stands out quite nicely.  If you turn off auto-mode you won't run in to problems like this.
Designing Towers
Towers come in groups of three.  The fire tower, like most other towers in Widget TD, come in three different sizes each with a different attack strength.  A simple upgrade path for the towers was chosen to ease the learning curve of the game.
Poison tower group.  These overblown plants emit puffs of poisonous smoke.  As the image shows, if the player were to build these three species close to one another, the cloud of poison becomes overly bright.  The puffs of smoke are made by mesh particle emitters in order to give the correct shape and feel to these bloated vegetables.
Particles, Physics and Special Effects
The physics engine is great for explosions.  If you don't want to animate explosions by hand, you can use the built-in physics engine.  Individual fragments of an enemy robot are activated when it is killed.  Here we replaced a complete mesh with seven individual fragments.  Each fragment consists of a mesh, a collider and a particle emitter.  Particle effects for smoke and sparks add nicely to the overall effect.
Spiraling out of control.  These missiles use forces applied to a rigidbody to simulate exhaust thrust. For a spiraling missile effect, a velocity-dependent torque is used to simulate an out-of-order control flap.
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