#include "stdafx.h"

#define NUM_PC 4

#define BUFSIZE 512
GLuint selectBuf[BUFSIZE];

GLfloat ctrlpoints[NUM_PC][3], initctrlpoints[NUM_PC][3] = {
	{ -4.0, -4.0, 0.0 },{ -2.0, 4.0, 0.0 },
	{ 2.0, -4.0, 0.0 },{ 4.0, 4.0, 0.0 } },

	corr_points[NUM_PC][3] = {
		{ .0, -1.0, 0.0 },{ 1.0, 1.0, 0.0 },
		{ -1.0, 0., 0.0 },{ .0, 1.0, 0.0 } };

void init_puntos_de_control(void)
{
	int i, j;
	for (i = 0; i<NUM_PC; i++)
		for (j = 0; j<3; j++)
			ctrlpoints[i][j] = initctrlpoints[i][j];
}

void init(void)
{
	init_puntos_de_control();
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glShadeModel(GL_FLAT);
	glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, NUM_PC, &ctrlpoints[0][0]);
	glMapGrid1f(31, 0.0, 1.0);
	glEnable(GL_MAP1_VERTEX_3);
}


void anallizename(int name)
{
	int i;

	if (name<1 || name>NUM_PC)return;

	for (i = 0; i<3; i++)
		ctrlpoints[name - 1][i]
		+= corr_points[name - 1][i];

	glClearColor(0.0, 0.0, 0.0, 0.0);
	glShadeModel(GL_FLAT);
	glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, NUM_PC, &ctrlpoints[0][0]);
	glMapGrid1f(31, 0.0, 1.0);
	glEnable(GL_MAP1_VERTEX_3);

	glutPostRedisplay();
}



/*  processHits prints out the contents of the
*  selection array.
*/
void processHits(GLint hits, GLuint buffer[])
{
	if (hits == 0) {/*restore all colors*/
		init();
		return;
	}

	unsigned int i, j;
	GLuint names, *ptr;

	ptr = (GLuint *)buffer;
	for (i = 0; i < hits; i++) {    /*  for each hit  */
		names = *ptr;
		ptr += 3;		
		for (j = 0; j < names; j++)  /*  for each name */
			anallizename(*ptr++);
	}
}


void display(int mode)
{
	int i;
	glColor3f(1.0, 1.0, 1.0);
	
	glEvalMesh1(GL_LINE, 0, 31);
	
	/* The following code displays the control points as dots. */	
	glColor3f(1.0, 1.0, 0.0);

	for (i = 0; i < NUM_PC; i++)
	{
		if (mode == GL_SELECT)
			glPushName(i + 1);		

		/* En lugar de GL_POINTS, mejor hacer un cuadrado
		alrededor de cada punto de control:*/
		glBegin(GL_QUADS);
		glVertex3f(ctrlpoints[i][0] - 0.5, ctrlpoints[i][1] - 0.5, 0);
		glVertex3f(ctrlpoints[i][0] - 0.5, ctrlpoints[i][1] + 0.5, 0);
		glVertex3f(ctrlpoints[i][0] + 0.5, ctrlpoints[i][1] + 0.5, 0);
		glVertex3f(ctrlpoints[i][0] + 0.5, ctrlpoints[i][1] - 0.5, 0);
		glEnd();
		if (mode == GL_SELECT)
			glPopName();
	}	
}


void pickPunto_De_Control(int button, int state, int x, int y)
{
	GLuint selectBuf[BUFSIZE];
	GLint hits;
	GLint viewport[4];

	if (button != GLUT_LEFT_BUTTON || state != GLUT_DOWN)
		return;

	glGetIntegerv(GL_VIEWPORT, viewport);
	glSelectBuffer(BUFSIZE, selectBuf);

	(void)glRenderMode(GL_SELECT);
	glInitNames();
	glPushName(0);

	glMatrixMode(GL_PROJECTION);
	glPushMatrix();
	glLoadIdentity();
	/*  create 5x5 pixel picking region near cursor location    */
	gluPickMatrix((GLdouble)x, (GLdouble)(viewport[3] - y),
		5.0, 5.0, viewport);
	glOrtho(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);	
	display(GL_SELECT);

	glMatrixMode(GL_PROJECTION);
	glPopMatrix();
	glMatrixMode(GL_MODELVIEW); /*respeta la logica
					de maniopulacion de glMatrixMode
					tomada en beziercurv()*/
	hits = glRenderMode(GL_RENDER);
	processHits(hits, selectBuf);
	glutPostRedisplay();
}

void RenderScene() {
	glClear(GL_COLOR_BUFFER_BIT);
	display(GL_RENDER);
	glFlush();
}

void reshape(int w, int h)
{
	glViewport(0, 0, (GLsizei)w, (GLsizei)h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glOrtho(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);
	
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

void keyboard(unsigned char key, int x, int y)
{
	switch (key) {
	case 27:
		exit(0);
		break;
	}
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(500, 500);
	glutInitWindowPosition(100, 100);
	glutCreateWindow(argv[0]);
	init();
	glutMouseFunc(pickPunto_De_Control);
	glutDisplayFunc(RenderScene);
	glutReshapeFunc(reshape);
	glutKeyboardFunc(keyboard);
	glutMainLoop();
	return 0;
}