Arcs and Circles

Functions
void	dog_draw_arc (uint8_t x_center, uint8_t y_center, uint8_t radius, uint8_t start_angle, uint8_t end_angle, uint8_t size, char mode)

Detailed Description

This file contains the prototype for the dog_draw_arc() function, which is used to set or clear an arc or unfilled circle.

Function Documentation

void dog_draw_arc	(	uint8_t	x_center,
		uint8_t	y_center,
		uint8_t	radius,
		uint8_t	start_angle,
		uint8_t	end_angle,
		uint8_t	size,
		char	mode
	)

This function is used set or clear an arc or unfilled circle of thickness 0 or 1. If both the start and end angle are the same number, then a circle is drawn.

Parameters

• x_center = X coordinate of the arc or circle's center.
• y_center = Y coordinate of the arc or circle's center.

• radius = Radius of the arc or circle

  Start and end angle are not represented in degrees nor radians. To convert from degrees to LCD_angles, use the following formula:
  LCD_angle = angle_degrees * (32/45)
  So:
  90 degrees = 64,
  180 degrees = 128,
  270 degrees = 192,
  360 degrees = 256 (due to 8-bit overflow, this is also zero) .
  

• start_angle = The start angle of the arc or circle
• end_angle = The end angle of the arc or circle
  
  
  
• size = The thickness of the point to place (0 or 1)
• mode = 's' for set, 'c' for clear

Algorithm

This function essentially draws lines between two computed coordinates through multiple iterations as it makes its way around the circle or arc.

• First computes the difference between provided angles
• The computes the number of required iterations.
• Then it computes X and Y coordinates for each iteration, drawing a line between them with the dog_draw_line() function.

Assumptions

• None