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11.26.2003 at 02:31PM PST, ID: 20809629
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C++/Opengl: Object Oriented Bezier Curves

Asked by eye30 in OpenGL Graphics & Game Programming

Tags: opengl, bezier, curve

Hi, I'm relatively new to OOP/C++/Opengl.  Thanks in advance.

I want to create multiple Bezier curves in a OOP class structure.  Eventually I would like to create multiple bezier curves with different attributes like x, y position, line thickness, etc.

I'm having difficulty with pointer/array portion.  I want to create an array of 100 bezier curves.  These individual curves are set up in an 6x3 array.  I'm getting 2 errors.  

My code:
#include <windows.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <GL/glut.h>
#include <stdlib.h>
#include <iostream.h>
#include <time.h>

//function prototypes

//Define bezier class for animation

class BezierClass {

      public:
      float x1,y1;
      float x2,y2;
      float x_cp1,y_cp1;
      float x_cp2,y_cp2;
      float x_cp3,y_cp3;
      float x_cp4,y_cp4;
      float xpos,ypos;

      BezierClass() {
      float bezierArray[6][3] =
                  { {x1, y1, 0.0},      /* 1st End Point */
                  {x_cp1, y_cp1, 0.0},      /* 1st Control P. */
                  {x_cp2, y_cp2, 0.0},      /* 2nd Control P. */
                  {x_cp3, y_cp3, 0.0},      /* 3rd Control P. */
                  {x_cp4, y_cp4, 0.0},      /* 3th Control P. */
                  {x2, y2, 0.0} };            /* 2nd End Point */;

      }

};


/* Create an array of type bezierClass that may hold 100 beziers */
BezierClass bezierArray[100];
int beziernum=0;
int totalbezier=5;
float zoom = -7;

void InitGL(int Width, int Height)
{
      glClearDepth(1.0);
      glClearColor(0.0, 0.0, 0.0, 0.0);      /* bg color = black */
      glDepthFunc(GL_LESS);                  /* nearer appears nearer */
      glEnable(GL_DEPTH_TEST);            /* enable depth testing */
      glShadeModel(GL_SMOOTH);            /* shade colors smooth */
      glMatrixMode(GL_PROJECTION);            /* switch the matrix */
      glLoadIdentity();                  /* reset the cur. matrix */
      gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);
      glMatrixMode(GL_MODELVIEW);            /* switch matrix back */
}

void DrawGLScene(void)
{
      int i;                              /* temp var */

      /* Clear the screen and the buffers */
      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
      glLoadIdentity();                  /* reset cur. matrix */
      glTranslatef(0.0f, 0.0f, -10.0f);      /* move the cam */

      /* ok, this is the main point of our bezier curve
       * void glMap1f(GLenum target, float u1, float u2, int stride
       *          int order, const float *points);
       * target is one of these:
       * GL_MAP1_VERTEX_3      (Vertex Coordinates (xyz))
       * GL_MAP1_VERTEX_4      (Vertex Coordinates (xyzw))
       * GL_MAP1_INDEX      (Color Index)
       * GL_MAP1_COLOR_4      (Color Values (rgba))
       * GL_MAP1_NORMAL      (Normal Coordinates)
       * GL_MAP1_TEXTURE_COORD_1/2/3/4 (Texture Coordinates(s/st/str/strq)
       *
       * no idea what u1 and u2 these are, but it works with 0.0 and 1.0
       * stride is the distance between each point on the curve
       * order should always just fit the number of the points
       * points is just a pointer to the pointdata(array)*/
////********error here: says "pointer/array required"//////////////

                glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 6, &bezierArray[0][0]);
               

      glEnable(GL_MAP1_VERTEX_3);            /* enable the mode */

      glColor3f(1.0, 1.0, 1.0);            /* set color to white */

      glBegin(GL_LINE_STRIP);                  /* start drawing */
            for(i = 0; i <= 60; i++)
            {
                  /* start evaluating the points
                   * void glEvalCoord1f(float u);
                   * u is the current point we evaluate */
                  glEvalCoord1f((float)i/60.0f);
            }
      glEnd();                        /* stop drawing */

      glPointSize(3.0);                  /* set point size to 3px */
      glColor3f(1.0f, 1.0f, 0.0f);            /* set color to yellow */
      glBegin(GL_POINTS);                  /* start drawing again */
            for(i = 0; i < 6; i++)
            {
                  /* draw all control/end points */
////********error here: says "pointer/array required"//////////////
                  glVertex3fv(&bezierArray[i][0]);
            }
      glEnd();

      glFlush();                        /* Flush all buffers */
      glutSwapBuffers();                  /* Sawp buffers */
      return;
}

void reshape(int w, int h)
{
      glViewport(0, 0, (GLint) w, (GLint) h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();

      if ( h==0)
            gluPerspective(45, (GLdouble)w, 1.0, 100.0);
      else
            gluPerspective(45, (GLdouble)w/(GLdouble)h,1.0, 100.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

//test-trying to make the bezier curve move in y direction.

void idle_func (void)
{
for (beziernum=0 ;beziernum < 100; beziernum++) {
   //bezierArray[beziernum].ypos+=1;

   }
   glutPostRedisplay();
}

/*  Main Loop
 *  Open window with initial window size, title bar,
 *  RGBA display mode, and handle input events.
 */
int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
   glutInitWindowSize (800, 600);
   glutCreateWindow (argv[0]);
   glutReshapeFunc (reshape);
   glutDisplayFunc (DrawGLScene);
   glutIdleFunc (idle_func);
   glutMainLoop();
   return 0;
}
//end of code



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[+][-]11.26.2003 at 09:33PM PST, ID: 9829715

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[+][-]11.26.2003 at 09:58PM PST, ID: 9829798

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About this solution

Zone: OpenGL Graphics & Game Programming
Tags: opengl, bezier, curve
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Solution Provided By: sunnycoder
Participating Experts: 2
Solution Grade: A
 
 
[+][-]11.26.2003 at 10:21PM PST, ID: 9829865

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[+][-]03.12.2005 at 11:08PM PST, ID: 13527595

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