OpenGL Project 6 - Bezier Curves

This project was really simple but was a good introduction into bezier curves and their uses. I didn't have a lot of inspiration for this project but the result was fun and it looked cool. This introduction to bezier curves was a great experience because it gave me an insight into how a lot of graphical tools create curves and splines.

Check out the video demonstration:

Here's the code to draw the curve:

struct Bezier {
	//line layout should be p1 c1 c2 p2 from end to end
	struct Point p1, p2;
	struct Point c1, c2;
	struct Point normal;
	float t;
	float r, g, b;
};

void drawBezier(struct Bezier *b) {
	glLineWidth(2);
	glColor3f(b->r, b->g, b->b);
	glBegin(GL_LINE_STRIP);
	for (int i = 0; i < b->t; ++i) {
		float t = (float)i / (float)(b->t);
		float omt = 1.f - t;
		float x = omt * omt*omt*(b->p1.x) + 3.f*t*omt*omt*(b->c1.x) + 3.f*t*t*omt*(b->c2.x) + t * t*t*(b->p2.x);
		float y = omt * omt*omt*(b->p1.y) + 3.f*t*omt*omt*(b->c1.y) + 3.f*t*t*omt*(b->c2.y) + t * t*t*(b->p2.y);
		float z = omt * omt*omt*(b->p1.z) + 3.f*t*omt*omt*(b->c1.z) + 3.f*t*t*omt*(b->c2.z) + t * t*t*(b->p2.z);
		
		float p = t - 0.5;
		float hue = p * 120;
		float hsv[3] = { hue, Time + 0.2, 1. };
		float rgb[3] = { 1, 1, 1 };
		HsvRgb(hsv, rgb);

		if (debugPoints)
		{
			glColor3f(1, 0, 0);
		}
		else {
			glColor3fv(rgb);
		}
		glVertex3f(x, y, z);
	}
	glEnd();


	//Draw the control lines
	if (linesOn) {
		glBegin(GL_LINE_STRIP);
		glColor3f(1, 1, 1);
		glVertex3f(b->p1.x, b->p1.y, b->p1.z);
		glVertex3f(b->c1.x, b->c1.y, b->c1.z);
		glVertex3f(b->c2.x, b->c2.y, b->c2.z);
		glVertex3f(b->p2.x, b->p2.y, b->p2.z);

		glEnd();

	}
	//Draw the debug lines
	if (debugPoints) {
		glBegin(GL_LINE_STRIP);
		glColor3f(1, 1, 1);
		glVertex3f(b->p1.x, b->p1.y, b->p1.z);
		glVertex3f(b->p2.x, b->p2.y, b->p2.z);
		glEnd();
	}

	//Draw control points
	if (pointsOn) {
		glPointSize(10);
		glBegin(GL_POINTS);

		glColor3f(0, 1, 0);		//Draw end points in green
		glVertex3f(b->p1.x, b->p1.y, b->p1.z);
		glVertex3f(b->p2.x, b->p2.y, b->p2.z);
		glColor3f(1, 1, 0);		//Draw control points in yellow
		glVertex3f(b->c1.x, b->c1.y, b->c1.z);
		glVertex3f(b->c2.x, b->c2.y, b->c2.z);

		glEnd();
	}


}