1. Basic Graphics
Drawing Shapes 1

2. Learning Goals By the end of the lesson you should know:
Using the Helper Library to:
Use predefined colours
Create custom colours
Where to write our graphics code
The screen resolution
How to draw a line
How to draw a rectangle
How to draw a filled rectangle

3. The Helper Library
The Helper library built into the Java Game Engine allows you to do a number of things:
Generate random values within a given range
Take advantage of a number of predefined colours
Use custom colours
Using the Helper Library
Like other libraries such as Math, we simply need to use the library’s name followed by the desired value or command
E.g. Helper.BLACK

4. Predefined Colours
There are 13 predefined colours you can take advantage of:
WHITE
RED
GREEN
BLUE
ORANGE
YELLOW
GRAY
BLACK
PINK
CYAN
DARK_GRAY
LIGHT_GRAY
MAGENTA
To use these colours you need to follow the Helper. prefix with the colour you need:
Helper.WHITE or Helper.BLACK

5. Custom Colours
In order to create custom colours it is best practice to create a variable to store that new colour. The data type for your variable will be Color
From here we will take advantage of one of two Helper commands:
Helper.GetColor(int red, int green, int blue)
Helper.GetColor(int red, int green, int blue, int transparency)
The red, green and blue values are numbers between 0 to Think of it like mixing paint, these three colours can produce any colour you want.
HINT: Go to colorpicker.com to get exact values for any colour you want
Transparency is also a value from 0 to 255, in this case however the number represents how transparent (see-through) the colour is is completely opaque and 0 and invisible.
When creating your colours, it is best to make these variables global, but they do NOT need to be static.
E,g. Color skyColor = Helper.GetColor(0,0,200);

6. Where to Draw? public void Draw(GameContainer gc, Graphics2D gfx) {
For our purposes we will be using the Game project on the Moodle which has the Java Game Engine built in and ready to go.
Recall that all of our drawing commands will go in the Draw command of our Game Loop.
public void Draw(GameContainer gc, Graphics2D gfx) {
//Add your draw code here }

7. The screen X
(0,0)
You will be drawing to the game window which you specify as a certain size in the Main code of the Game Project
Assume you use the default values of 800 pixels wide by 600 pixels high
Also note that the (0,0) origin is NOT in the bottom left of the screen, it is at the top left of the screen.
This implies coordinate (800,600) is located at the bottom right of the screen.
This means that x in creases as you move right and y increases as your move DOWN Y
(800,600)

8. Draw a Line Draw.Line(gfx,50,125,300,200,3,Helper.RED,0.5f)
Draw.Line(gfx, x1, y1, x2, y2, lineWidth, Color, transparency)
gfx represents your game window, leave this alone
x1, y1 is the coordinate of the first end point of the line
x2, y2 is the coordinate of the second end point of the line
lineWidth is the number of pixels wide the line is
Color is the colour of the line, e.g. Helper.RED
transparency is how see-through the line is, a float number from 0 to 1 where 0 is invisible
Example: Draw a red line from (50,125) to (300,200) that is half transparent and 3 pixels wide
Draw.Line(gfx,50,125,300,200,3,Helper.RED,0.5f)

9. Draw a Rectangle
Draw.Rect(gfx, x, y, width, height, lineWidth, color, transparency)
gfx represents your game window, leave this alone
x,y is the coordinate for the rectangle’s top left corner
width, height are the dimensions of the rectangle
color is the border’s colour
transparency is how see-through the line is, a float number from 0 to 1 where 0 is invisible
Example: Draw a 200x400 White opaque rectangle at (25,100)
Draw.Rect(gfx,25,100,200,400,5,Helper.WHITE, 1f);

10. Draw a Filled Rectangle
Draw.FillRect(gfx, x, y, width, height, color, transparency)
gfx represents your game window, leave this alone
x,y is the coordinate for the rectangle’s top left corner
width, height are the dimensions of the rectangle
color is colour the rectangle is filled in with
transparency is how see-through the line is, a float number from 0 to 1 where 0 is invisible
Example: Draw a 300x100 ¾ opaque yellow filled rectangle at (40,150)
Draw.FillRect(gfx,40,150,300,100,Helper.YELLOW,0.75f);