/*  curbe_Bezier.c
 *
 Programul utilizeaza evaluatorii pentru determinarea
 punctelor de pe curba Bezier
 */
#include "glos.h"

#include <GL/gl.h>
#include <glu.h>
#include <glaux.h>

void myinit(void);
void CALLBACK myReshape(GLsizei w, GLsizei h);
void CALLBACK display(void);
#define nr_puncte 4

GLfloat ctrlpoints[nr_puncte][3] = {
	//sunt date coordonatele celor 4 puncte de control
    { -4.0, 0.0, 0.0}, { -3.0, 2.0, 0.0},
	{-1.0, 2.0, 0.0}, {0.0,0.0,0}  };

GLfloat ctrlpoints2[nr_puncte][3] = {
	//sunt date coordonatele celor 4 puncte de control
    { 0.0, 0.0, 0.0}, { 1.0, -2.0, 0.0},
	{3.0, -2.0, 0.0}, {4.0,0.0,0}  };



void myinit(void)
{
    glClearColor(1.0, 1.0, 1.0, 1.0); //culoarea background-ului

/*functia defineste caracteristicile curbei:
-tipul punctelor de control date in vectorul ctrlpoints, si al
datelor de iesire generate de functia de evaluare glEvalCoord1f
-valorile extreme luate de parametrul u (0 si 1 in acst caz)
-numarul coordonatelor date pentru fiecare punct de control, in tabloul
ctrlpoints
-numarul punctelor de control pe baza carora se va determina ordinul curbei
(numar puncte-1)
-vectorul punctelor de control
   */

    glEnable(GL_MAP1_VERTEX_3);	//se valideaza un anumit tip de evaluare
    glShadeModel(GL_FLAT); 	//umbrire constanta pe poligoane
	glLineStipple (1, 0x0F0F);
}

void CALLBACK display(void)
{
    int i;

    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(0.0, 0.0, 0.0);
glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ctrlpoints[0][0]);	//culoarea curenta de desenare
    glBegin(GL_LINE_STRIP);		//se deseneaza curba prin segmente de dreapta
    for (i = 0; i <= 30; i++)
        glEvalCoord1f((GLfloat) i/30.0); //pentru cele 30 varfuri determinate de
								// functia glEvalCoord1f
    glEnd();

	glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ctrlpoints2[0][0]);	//culoarea curenta de desenare
    glBegin(GL_LINE_STRIP);		//se deseneaza curba prin segmente de dreapta
    for (i = 0; i <= 30; i++)
        glEvalCoord1f((GLfloat) i/30.0); //pentru cele 30 varfuri determinate de
								// functia glEvalCoord1f
    glEnd();

	/* Se afiseaza punctele de control. */
    glPointSize(5.0);	// de dimensiune 5
    glColor3f(1.0, 0.0, 0.0);	// culoare rosie
    glBegin(GL_POINTS);
    for (i = 0; i < nr_puncte; i++)
        glVertex3fv(&ctrlpoints[i][0]);
    glEnd();



	//poligonul caracteristic ?


	glEnable(GL_LINE_STIPPLE);
	glColor3f(1.0, 0.0, 1.0);
	glBegin (GL_LINE_STRIP);
	for (i=0; i<nr_puncte; i++)
		glVertex3fv(&ctrlpoints2[i][0]);
	glEnd();
	 glPointSize(5.0);	// de dimensiune 5
    glColor3f(1.0, 0.0, 0.0);	// culoare rosie
    glBegin(GL_POINTS);
    for (i = 0; i < nr_puncte; i++)
        glVertex3fv(&ctrlpoints2[i][0]);
    glEnd();



	//poligonul caracteristic ?
	glEnable(GL_LINE_STIPPLE);
	glColor3f(1.0, 0.0, 1.0);
	glBegin (GL_LINE_STRIP);
	for (i=0; i<nr_puncte; i++)
		glVertex3fv(&ctrlpoints2[i][0]);
	glEnd();

    glFlush();
}

void CALLBACK myReshape(GLsizei w, GLsizei h)
{
    if (!h) return;
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h)
    glOrtho(-5.0, 5.0, -5.0*(GLfloat)h/(GLfloat)w,
        5.0*(GLfloat)h/(GLfloat)w, -5.0, 5.0);
    else
    glOrtho(-5.0*(GLfloat)w/(GLfloat)h,
        5.0*(GLfloat)w/(GLfloat)h, -5.0, 5.0, -5.0, 5.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

int main(int argc, char** argv)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB);
    auxInitPosition (0, 0, 500, 500);
    auxInitWindow ("Curbe Bezier");
    myinit();
    auxReshapeFunc (myReshape);
    auxMainLoop(display);
    return(0);
}