How you can draw an ellipse in C language?

Answer 1

The C language does not provide any support for graphics as standard. C is designed to be as generic as possible, but graphics are a system-specific feature. To use graphics in C you need a third-party graphics library that supports your operating system and hardware, however generic libraries such as OpenGL are available. Nevertheless, it is not possible to draw curves, you can only approximate a curve using a series of short lines. The shorter the lines and the higher the resolution, the smoother the curve will appear.

Assuming you have access to an OpenGL library, you can draw an ellipse as follows:

void DrawEllipse(float cx, float cy, float rx, float ry, int num_segments)

{

const float pi = atan (1) * 4;

float theta = 2 * pi / float (num_segments);

float c = cosf (theta);

float s = sinf (theta);

float x = 1;

float y = 0;

float t;

glBegin (GL_LINE_LOOP);

for (int i = 0; i < num_segments; ++i)

{

glVertex2 f (x * rx + cx, y * ry + cy);

t = x;

x = c * x - s * y;

y = s * t + c * y;

}

glEnd();

}