#include <GL/glut.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <math.h>

// Define a constant for the value of PI
#define GL_PI 3.1415f

// Rotation amounts
static GLfloat xRot = 0.0f;
static GLfloat yRot = 0.0f;

// Flags for effects
#define MODE_SOLID 0
#define MODE_LINE  1
#define MODE_POINT 2

int iMode = MODE_SOLID;
GLboolean bEdgeFlag = true;

///////////////////////////////////////////////////////////////////////////////
// Reset flags as appropriate in response to menu selections
void ProcessMenu(int value)
	{
	switch(value)
		{
		case 1:
			iMode = MODE_SOLID;
			break;

		case 2:
			iMode = MODE_LINE;
			break;

		case 3:
			iMode = MODE_POINT;
			break;

		case 4:
			bEdgeFlag = true;
			break;

		default:
			bEdgeFlag = false;
			break;
		}

	glutPostRedisplay();
	}


// Called to draw scene
void RenderScene(void)
	{
	// Clear the window
	glClear(GL_COLOR_BUFFER_BIT);


	// Draw back side as a polygon only, if flag is set
	if(iMode == MODE_LINE)
		glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);

	if(iMode == MODE_POINT)
		glPolygonMode(GL_FRONT_AND_BACK,GL_POINT);

	if(iMode == MODE_SOLID)
		glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);


	// Save matrix state and do the rotation
	glPushMatrix();
	glRotatef(xRot, 1.0f, 0.0f, 0.0f);
	glRotatef(yRot, 0.0f, 1.0f, 0.0f);


	// Begin the triangles
	glBegin(GL_TRIANGLES);

		glEdgeFlag(bEdgeFlag);
		glVertex2f(-0.2f, 0.0f);
		glEdgeFlag(true);
		glVertex2f(0.2f, 0.0f);
		glVertex2f(0.0f, 0.4f);

		glVertex2f(-0.2f,0.0f);
		glVertex2f(-0.6f,-0.2f);
		glEdgeFlag(bEdgeFlag);
		glVertex2f(-0.2f,-0.4f);
		glEdgeFlag(true);

		glVertex2f(-0.2f,-0.4f);
		glVertex2f(0.0f, -0.8f);
		glEdgeFlag(bEdgeFlag);
		glVertex2f(0.2f, -0.4f);		
		glEdgeFlag(true);

		glVertex2f(0.2f, -0.4f);		
		glVertex2f(0.6f, -0.2f);
		glEdgeFlag(bEdgeFlag);
		glVertex2f(0.2f, 0.0f);
		glEdgeFlag(true);

		// Center square as two triangles
		glEdgeFlag(bEdgeFlag);
		glVertex2f(-0.2f, 0.0f);
		glVertex2f(-0.2f,-0.4f);
		glVertex2f(0.2f, 0.0f);
		
		glVertex2f(-0.2f,-0.4f);
		glVertex2f(0.2f, -0.4f);
		glVertex2f(0.2f, 0.0f);
		glEdgeFlag(true);
	
	// Done drawing Triangles
	glEnd();

	// Restore transformations
	glPopMatrix();

	// Flush drawing commands
	glFlush();
	}

// This function does any needed initialization on the rendering
// context. 
void SetupRC()
	{
	// Black background
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f );

	// Set drawing color to green
	glColor3f(0.0f, 1.0f, 0.0f);
	}

void SpecialKeys(int key, int x, int y)
	{
	if(key == GLUT_KEY_UP)
		xRot-= 5.0f;

	if(key == GLUT_KEY_DOWN)
		xRot += 5.0f;

	if(key == GLUT_KEY_LEFT)
		yRot -= 5.0f;

	if(key == GLUT_KEY_RIGHT)
		yRot += 5.0f;

	// Refresh the Window
	glutPostRedisplay();
	}

int main(int argc, char* argv[])
	{
	int nModeMenu;
	int nEdgeMenu;
	int nMainMenu;

        glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB );
	glutInitWindowSize(640,480);
	glutCreateWindow("Solid and Outlined Star");
	
	// Create the Menu
	nModeMenu = glutCreateMenu(ProcessMenu);
	glutAddMenuEntry("Solid",1);
	glutAddMenuEntry("Outline",2);
	glutAddMenuEntry("Points",3);

	nEdgeMenu = glutCreateMenu(ProcessMenu);
	glutAddMenuEntry("On",4);
	glutAddMenuEntry("Off",5);

	nMainMenu = glutCreateMenu(ProcessMenu);
	glutAddSubMenu("Mode", nModeMenu);
	glutAddSubMenu("Edges", nEdgeMenu);
	glutAttachMenu(GLUT_RIGHT_BUTTON);
	
	glutSpecialFunc(SpecialKeys);
	glutDisplayFunc(RenderScene);
	SetupRC();
	glutMainLoop();

	return 0;
	}