Computergraphik_Hopp/Code/template_koordinatensystemUndPunkte.c

#include <GL/glut.h>
#include <string.h>
#include <math.h>
#include <stdio.h>

#define PI 3.14159265358979323846
#define PIf 3.14159265358979323846f

static int width = 800;
static int height = 600;

void init(int argc, char** argv) {
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE);
	glutInitWindowSize(width, height);
	glutInitWindowPosition(100, 100);
	glViewport(0, 0, width, height);
	glutCreateWindow("Programmieruebung Kreis-Plotter");
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0, width, 0, height);
	glMatrixMode(GL_MODELVIEW);
	glEnable(GL_POINT_SMOOTH);
	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}

void drawCoordinateSystem(float* origin, int xLength, int yLength, int numTicksX, int numTicksY, float minX, float maxX, float minY, float maxY) {

	float xTickDistance = (float) xLength / (float) numTicksX;
	float yTickDistance = (float) yLength / (float) numTicksY;

	char label[10];

    double resX = (maxX - minX) / xLength;
    double resY = (maxY - minY) / yLength;

	glColor3f(0.0, 0.0, 0.0);
	/* drawing the coordinate system */
	glBegin(GL_LINES);
	// x axis
	glVertex2f(origin[0], origin[1]);
	glVertex2f(origin[0] + xLength, origin[1]);
	// y axis
	glVertex2f(origin[0], origin[1]);
	glVertex2f(origin[0], origin[1] + yLength);
	// arrow head at x axis
	glVertex2f(origin[0] + xLength, origin[1]);
	glVertex2f(origin[0] + xLength - 15, origin[1] - 10);
	glVertex2f(origin[0] + xLength, origin[1]);
	glVertex2f(origin[0] + xLength - 15, origin[1] + 10);
	// arrow head at y axis
	glVertex2f(origin[0], origin[1] + yLength);
	glVertex2f(origin[0] - 10, origin[1] + yLength - 15);
	glVertex2f(origin[0], origin[1] + yLength);
	glVertex2f(origin[0] + 10, origin[1] + yLength - 15);
	glEnd();

	// drawing ticks at x axis
    for (int j = 0; j < xLength; j = j + xTickDistance) {
		glBegin(GL_LINES);
		glVertex2f(origin[0] + j, origin[1] - 5);
		glVertex2f(origin[0] + j, origin[1] + 5);
		glEnd();
		sprintf(label, "%5.2f", minX + (j*resX));
		glRasterPos2i((int) round(origin[0] + j - (8 * 5)), (int) round(origin[1] - 13 - 10));
        for (int k = 0; k < 5; k++) {
			glutBitmapCharacter(GLUT_BITMAP_8_BY_13, label[k]);
		}
	}

	// drawing ticks at y axis
    for (int j = 0; j < yLength; j = j + yTickDistance) {
		glBegin(GL_LINES);
		glVertex2f(origin[0] - 5, origin[1] + j);
		glVertex2f(origin[0] + 5, origin[1] + j);
		glEnd();
		sprintf(label, "%5.2f", minY + (j*resY));
		glRasterPos2i((int) round(origin[0] - (8 * 5) - 10), (int) round(origin[1] + j - 13 / 2));
        for (int k = 0; k < 5; k++) {
			glutBitmapCharacter(GLUT_BITMAP_8_BY_13, label[k]);
		}
	}
}


void drawCircle(float origin[2], float center[2], float radius, GLint numPoints)
{
	//////////////////////////////////////////////////////////////////////////////////////////////
	// - calculate numPoints points on the surface of the circle with given center and radius
	//		hint: see circle equation in parametric form 
	// - position points in the coordinate system starting at given origin
	// - draw the points by OpenGL commands

    glBegin(GL_POINTS);
    for (float i = 0.0f; i < 2*PIf; i += (2*PIf)/numPoints) {
        float x = origin[0] + center[0] + cosf(i) + radius * cosf(i);
        float y = origin[1] + center[1] + sinf(i) + radius * sinf(i);
        glVertex2f(x, y);
    }
    glEnd();

	//////////////////////////////////////////////////////////////////////////////////////////////
}




void display(void)
{
	int n;
	int xTickDistance = 50;
	int yTickDistance = 50;
	int numPoints = 30;
	float radius[] = { 50, 100, 150 };
	float center[] = { 300, 200 };
	float origin[] = { 100, 100 };
	GLfloat c[] = { 0.0,0.0,0.0 };
	int xLength = 600;
	int yLength = 400;
	float size = 2;
	

	/* settings for the coordinate system */
	int numTicksX = 6;
	int numTicksY = 4;
	float minX = 0;
	float maxX = 600;
	float minY = 0;
	float maxY = 400;

	/* clearing the background color */
	glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT);

	drawCoordinateSystem(origin, xLength, yLength, numTicksX, numTicksY, minX, maxX, minY, maxY);


	for (n = 0; n < 3; n++) {

		///////////////////////////////////////////////////////////////////////////////
		// - set the point size different for each loop iteration
		// - set the color different for each loop iteration

        if (n == 0) {
            glColor3f(1.0f, 0.0f, 0.0f);
            glPointSize(2.0f);
        } else if (n == 1) {
            glColor3f(0.0f, 1.0f, 0.0f);
            glPointSize(4.0f);
        } else if (n == 2) {
            glColor3f(0.0f, 0.0f, 1.0f);
            glPointSize(6.0f);
        }

		//////////////////////////////////////////////////////////////////////////////
		drawCircle(origin, center, radius[n], numPoints);
	}


	glFlush();
}


int main(int argc, char** argv)
{
	init(argc, argv);

	glutDisplayFunc(display);
	glutMainLoop();
	return 0;
}