Interpolation curve with opengl using evaluators - c

Question

This code almost works, but the problem is that it leaves behind the last control point like if it doesn't exist. I cannot find the error and I don't know why, I checked the transformation matrix and the converted control point many times but nothing
#include <GL/glew.h>
#include <GL/freeglut.h>
#include <stdio.h>
#include <math.h>
// Begin globals.
static int numVal = 0;
// Final control points.
static float controlPoints[4][3] =
{
{-30.0, 0.0, 0.0}, { -10.0, 20.0, 0.0},
{10.0, -20.0, 0.0}, {30.0, 0.0, 0.0}
};
//Matrix multiplication Mb^-1 * Mi
static float conversion[4][4] =
{
{1.0,0.0,0.0,0.0},{-0.8333,3.0,-1.5,0.3333},{0.3333,-1.5,3.0,-0.8333},{0.0,0.0,0.0,1.0}
};
//End globals
//Control point conversion for evaluator
void convertcp(float ctrlpoints[4][3]){
int i,j,k;
float tot = 0.0;
for(i = 0; i < 4;i++){
for(j = 0;j < 4;j++){
ctrlpoints[i][j] = 0;
for(k = 0; k < 3;k++){
ctrlpoints[i][j] += conversion[i][k] * controlPoints[k][j];
}
}
}
}
// End globals.
// Initialization routine.
void setup(void){glClearColor(1.0, 1.0, 1.0, 0.0);}
// Drawing routine.
void drawScene(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f(0.0, 0.0, 0.0);
int indx;
float ctrlpoints[4][3];
convertcp(ctrlpoints);
// Draw the control polygon in light gray.
glColor3f(0.7,0.7, 0.7);
glBegin(GL_LINE_STRIP);
for (indx = 0; indx < 4; indx++)
glVertex3fv(controlPoints[indx]);
glEnd();
// Specify and enable the Bezier curve.
glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ctrlpoints[0][0]);
glEnable(GL_MAP1_VERTEX_3);
// Draw the Bezier curve by defining a sample grid and evaluating on it.
glColor3f(0.0, 0.0, 0.0);
glMapGrid1f(100, 0.0, 1.0);
glEvalMesh1(GL_LINE, 0, 100);
// Draw the Bezier control points as dots.
glPointSize(5.0);
glColor3f(0.0, 1.0, 0.0);
glBegin(GL_POINTS);
for (indx = 0; indx < 4; indx++)
glVertex3fv(controlPoints[indx]);
glEnd();
// Highlight selected control point,
glColor3f(1.0, 0.0, 0.0);
glBegin(GL_POINTS);
glVertex3fv(controlPoints[numVal]);
glEnd();
glutSwapBuffers();
glutPostRedisplay();
}
// OpenGL window reshape routine.
void resize(int w, int h)
{
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-50.0, 50.0, -50.0, 50.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
// Keyboard input processing routine.
void keyInput(unsigned char key, int x, int y)
{
switch (key)
{
case 27:
exit(0);
break;
case ' ':
if (numVal < 3) numVal++;
else numVal = 0;
glutPostRedisplay();
break;
default:
break;
}
}
// Callback routine for non-ASCII key entry.
void specialKeyInput(int key, int x, int y)
{
if(key == GLUT_KEY_UP) controlPoints[numVal][2] += 1.0;
if(key == GLUT_KEY_DOWN) controlPoints[numVal][2] -= 1.0;
if(key == GLUT_KEY_LEFT) controlPoints[numVal][0] -= 1.0;
if(key == GLUT_KEY_RIGHT) controlPoints[numVal][0] += 1.0;
glutPostRedisplay();
}
// Routine to output interaction instructions to the console window.
void printInteraction(void)
{
printf("Interaction:\n");
printf("Press space to select a control point.\n");
printf("Press the arrow keys to move the selected control point.\n");
}
// Main routine.
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitContextVersion(4, 3);
glutInitContextProfile(GLUT_COMPATIBILITY_PROFILE);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowSize(500, 500);
glutInitWindowPosition(100, 100);
glutCreateWindow("Interpolating Curves");
glutDisplayFunc(drawScene);
glutReshapeFunc(resize);
glutKeyboardFunc(keyInput);
glutSpecialFunc(specialKeyInput);
glewExperimental = GL_TRUE;
glewInit();
setup();
glutMainLoop();
}