Towers lasers and spacecrafts example

Simple example of game scene with QGraphicsScene

This simple example mostly shows how to deal with

• QGraphicsScene::advance()
• QGraphicsItem::advance()
• QGraphicsItem::paint(…)

Overview

The example contains three classes with following responsabilities

• The scene is a QGraphicsScene
  • Creates and deletes new items (towers and mobile units)
• Towers
  • search for nearby units
  • shoot them if any
• Mobile units (fighters)
  • Move
  • Explode and die

View example on Youtube [youtube.com]

Main.cpp

The main() method creates a scene and a QTimer.
The timer calls Scene::advance() every 0.01 sec.

The Scene

• The scene constructor creates several towers
• Scene::advance() :
  • has a counter m_TicTacTimer
  • every 20th ticTac, a new mobile unit is created with a random position, direction and speed.
  • dead units are removed from the item list

scene.h

scene.cpp

Towers

• Towers search for nearby units
  • Search is performed by squared distance comparison
  • Search stops when a first item is found
  • Warning: n against n = O(n2) algorithm… Poor performances on large amount of items… but sufficient here.

• Towers shoot the located item if any
• after shooting, a tower must wait until its weapon is reloaded : it requires a “reload time” of 100ms
• The laser beam is drawn with lines of different thicknesses and colors

simpletower.h
simpletower.cpp

Mobile units

Life Cycle of a mobile unit :

• A mobile unit is created with 10 life points
• Position changes according to predefined direction and speed
• It loses life points if touched by a laser beam
• The unit explodes when lifepoints are exhausted
• The explosion has a duration.
• The explosion is drawn by painter->drawEllipse(…) with a growing radius

mobileunit.h

mobileunit.cpp

Categories:

• Developing_with_Qt
  • Games
• Learning
  • Demos_and_Examples