EZ
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12.1 Getting Started

Roughly speaking, using the EZ graphics library consists of 6 steps.

12.1.1 Example G1, A Polygon

Let's start with a small example. We'll create a 3DCanvas widget, display it and draw a shaded polygon in it. It demonstrate the steps outlined above.

/*************** Example G1 ******************************************/
#include "EZ.h"

static void eventHandler(EZ_Widget *, void *, int, XEvent *);
static void draw(EZ_Widget *);

main(int argc, char **argv)
{
  EZ_Widget *frame, *canvas;
  /* 
   * Initialize EZWGL, don't forget to 
   * initialize the graphics library also.
   */
  EZ_Initialize(argc, argv, 1);      /* notice the 1        */
  /*
   * canvases do not resize propertly as toplevel
   * widgets (bug!) It is recommended to put it
   * under a frame at least for now.
   */
  frame = EZ_CreateWidget(EZ_WIDGET_FRAME, NULL, 
                         EZ_FILL_MODE, EZ_FILL_BOTH,
                         0);
  canvas = EZ_CreateWidget(EZ_WIDGET_3D_CANVAS, frame,
                           EZ_WIDTH_HINT,  320, 
                           EZ_HEIGHT_HINT, 320,
                           EZ_EVENT_HANDLE, eventHandler, NULL,
                           0);
  /*
   * now display the canvas. One must first display
   * a 3DCanvas before calling any GL functions !!!
   */
  EZ_DisplayWidget(canvas);         

  /* now setup global GL attributes */
  EZ_RGBMode();                 /* we are using RGB mode  */
  EZ_ShadeModel(EZ_SMOOTH);     /* turn on smooth shading */
  /*
   * We'll draw a 2D polygon, so we don't have to setup
   * a complex projection matrix. The default matrix mode
   * is EZ_MODELVIEW. We just set the projection matrix
   * on this default matrix stack.
   */
  EZ_LoadIdentity();            /* clear the top mtx 2 id */     
  EZ_Ortho2(-1.0,1.0,-1.0,1.0); /* project the unit cube  */

  draw(canvas);                 /* draw the polygon       */
  EZ_EventMainLoop();           /* handle events          */
}

static void draw(EZ_Widget *canvas)
{
  EZ_Clear(EZ_COLOR_BUFFER_BIT); /* clear the frame buffer */

  EZ_Begin(EZ_POLYGON);          /* start a polygon        */
  EZ_Color3f(1.0,0.0,0.0);       /* each vertex has its clr*/
  EZ_Vertex2f(1.0,0.0);
  EZ_Color3f(1.0,1.0,0.0);
  EZ_Vertex2f(0.5,0.866);
  EZ_Color3f(0.0,1.0,0.0);
  EZ_Vertex2f(-0.5,0.866);
  EZ_Color3f(0.0,1.0,1.0);
  EZ_Vertex2f(-1.0,0.0);
  EZ_Color3f(0.0,0.0,1.0);
  EZ_Vertex2f(-0.5,-0.866);
  EZ_Color3f(1.0,0.0,1.0);
  EZ_Vertex2f(0.5,-0.866);
  EZ_End();                     /* the end of the polygon */
}
/* 
 * the event handler. It should handle at least the
 * EZ_REDRAW event and the EZ_RESIZE.
 */
static void eventHandler(EZ_Widget *canvas, void *data,
                         int eventType, XEvent *xevent)
{
  switch(eventType) 
    {
    case EZ_REDRAW:
    case EZ_RESIZE:
      draw(canvas);
      break;
    case EZ_KEY_PRESS:
      if(EZ_PressedKey == EZ_ESCAPE_KEY) exit(0);
      break;
    default:
      break;
    }
}
/*************** Example G1 ******************************************/  


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