Problem Description

Here's a program illustrating the use of timers to control the lights of a simulated drag strip starting tree.

Background & Techniques

Drag racing is a sport in which two vehicles race from a standing start for a fixed distance, usually 1/4 mile,  down a straight track with two lanes. 

This program was prompted by a user who is developing a drag strip simulation and wanted help in triggering the start with some visual clue.  My original version simply changed the color of  a circular shape at some random interval after an "Activate" button was clicked.  That evolved into a fairly complete model of the standard starting "tree", the Christmas tree, used in real races.

Lights are arranged in two columns, one for each racer.

 From top to bottom the rows indicate

	pre-staged (7 inches from the starting line),
	staged (at the starting line),
	three rows of yellow countdown light,
	the green "Go" light,
	and a red light if the racer starts too soon.

 Two users may use buttons to pre-stage and stage their dragsters and click the "Activate start sequence" button to start the countdown. When the green light is lit, "P' or "Q" keys will report reaction times for each player.  Pressing the keys too soon results in a red light condition on the tree.

 An "Auto stage" checkbox automates pre-staging, staging, and activating start sequence lights.  

For programmers, I have tried to comment the code well enough to make clear how the timers work.  Timer1 controls the yellow lights and the green start light on the tree.  The StartLightsOn integer starts at 0 and is incremented each rime the timer even exit occurs.  Lights are turned within the exit by changing the color of the appropriate Tshapes from a dark to light shade of yellow or green.   There are two starting modes used in drag racing.  "Sportsman" mode triggers the three yellow lights and the green start light at 1/.2 second intervals. "Professional"  mode lights all 6  yellow lights simultaneously followed by the green lights 0.4 seconds later.  The current time of day is saved as StartTime when the green lights are lit.

The "Auto Activate" checkbox introduces two additional timers, AutoTimer1 and AutoTimer2, one for each racer which are triggered at random intervals to simulate their pre-stage and stage lights.  When both racers are staged, the Onclick event exit for the Activate button is called to start the countdown process.  

The Boolean form property "KeyPreview" has been set to true to allow form KeyPress event exits to be taken regardless of which control has the focus.    Keys other than P or Q are ignored; those two keys cause the current time minus the StartTime value to be displayed as the response time for the appropriate racer.

No actual racing here - we'll leave that for the future.

Running/Exploring the Program 

• Download source
• Download  executable

Suggestions for Further Explorations

I believe that in real drag racing there is a minimum acceptable reaction time, below which the driver is red-lighted because he must have made a 'lucky guess".  If true, that restriction could be implemented here also.