3. AmigaBASIC
Amiga Tricks and Tips
The point and connection reader routines act as normal. Only the com putation of the graphic has a slight change to it The loop counts from one vanishing point to the next This counter also depends on the screen coordinates as an index.
Before screen display, die screen clears. Both vanishing points appear in their respective colors. When the grid for the second point is drawn, the program goes into a new character mode (see the table in Chapter 4 for the modes). When you draw with the second color, any overlapping between this color and red lines change to brown. At the end of the loop, the character mode returns to normal status, and the drawing color returns to 1.
A mouse and time interrupt activate. The first interrupt reads the sliders. The second interrupt resets the colors when you change them. The wait loop checks the program for one vanishing point or two vanishing points. If there are two, the value transfers over, and the screen is recal culated.
The system waits for a keypress. When this occurs, the program turns all objects, sliders, mouse and time readers off, and displays all established values on the screen.
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