added Screencast 20 on anti aliasing

020/020.c

@@ -0,0 +1,113 @@
+#include "screencasts.h"
+
+/*
+ * initializeGlobals()
+ * ------
+ * Initializes the global variables.
+ */
+void initializeGlobals(void)
+{
+  /* WINDOW */
+  windowHeight=DEF_WINDOW_HEIGHT;
+  windowWidth=DEF_WINDOW_WIDTH;
+
+  /* PROJECTION */
+  dim=DEF_DIM;
+  th=DEF_TH;
+  ph=DEF_PH;
+  fov=DEF_FOV;
+  asp=DEF_ASP;
+  ecX=DEF_ECX;
+  ecY=DEF_ECY;
+  ecZ=DEF_ECZ;
+}
+
+void windowKey(unsigned char key,int x,int y)
+{
+  /*  Exit on ESC */
+  if (key == 27) exit(0);
+
+  /* Change the X angle */
+  else if (key=='r') th = (th-5)%360;
+  else if (key=='R') th = (th+5)%360;
+
+  redisplayAll();
+}
+
+void drawScene(void)
+{
+  int i;
+  const float di = 0.95;
+  //  Draw background quad
+  glBegin(GL_QUADS);
+  glColor3f(1,1,1);
+  glVertex2f(-0.8*di,-0.4*di);
+  glVertex2f(-0.8*di,+0.4*di);
+  glVertex2f(+0.8*di,+0.4*di);
+  glVertex2f(+0.8*di,-0.4*di);
+  glEnd();
+
+  //  Two X's
+  //  Left  aliased
+  //  Right anti-aliased
+  for (i=-1;i<=1;i+=2) {
+    //  Aliased line setup
+    if (i<0) {
+      glDisable (GL_LINE_SMOOTH);
+      glDisable (GL_BLEND);
+      glLineWidth (1.5);
+    }
+    //  Anti-aliased line setup
+    else {
+      glEnable(GL_LINE_SMOOTH);
+      glEnable(GL_BLEND);
+      glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+      //glHint(TARGET, MODE)
+      //TARGET = GL_FRAGMENT_SHADER_DERIVATIVE_HINT, GL_LINE_SMOOTH_HINT, 
+      //         GL_TEXTURE_COMPRESSION_HINT, GL_POLYGON_SMOOTH_HINT
+      //MODE = GL_DONT_CARE, GL_NICEST, GL_FASTEST
+      glHint(GL_LINE_SMOOTH_HINT, GL_DONT_CARE);
+      //glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
+      //glHint(GL_LINE_SMOOTH_HINT, GL_FASTEST);
+      glLineWidth(1.5);
+    }
+    //  Draw X lines
+    glBegin(GL_LINES);
+    glColor3f(1,0,0);
+    glVertex2f(-di*Cos(th)+0.05*i,-di*Sin(th));
+    glVertex2f(+di*Cos(th)+0.05*i,+di*Sin(th));
+    glColor3f(0,0,1);
+    glVertex2f(-di*Cos(th)+0.05*i,+di*Sin(th));
+    glVertex2f(+di*Cos(th)+0.05*i,-di*Sin(th));
+    glEnd();
+  }
+}
+
+/*
+ *  main()
+ *  ----
+ *  Start up GLUT and tell it what to do
+ */
+int main(int argc,char* argv[])
+{
+  initializeGlobals();
+
+  /* screencast specific variables */
+  windowName = "OpenGL screenscasts 20: Anti-Aliasing";
+  screencastID = 20;
+
+  glutInit(&argc,argv);
+  glutInitDisplayMode(GLUT_RGB | GLUT_ALPHA);
+  glutInitWindowSize(windowWidth,windowHeight);
+  glutInitWindowPosition(450,350);
+  glutCreateWindow(windowName);
+
+  glutDisplayFunc(display);
+  glutReshapeFunc(displayReshape);
+  glutKeyboardFunc(windowKey);
+
+  redisplayAll();
+  glutMainLoop();
+  return 0;
+}
+

020/Makefile

@@ -0,0 +1,25 @@
+# Target to build
+TARGET = 020
+EXECS = ./$(TARGET)
+
+# Libraries - LINUX
+#LIBS=-lglut -lGLU
+# Libraries - OSX
+LIBS=-framework OpenGL -framework GLUT
+
+all: $(TARGET)
+
+# Generic compile rules
+.c.o: 
+	gcc -c -g -O -Wall $<
+
+# Generic compile and link
+%: %.c screencasts.a
+	gcc -Wall -O3 -o ./$@ $^ $(LIBS)
+
+clean:
+	rm -f $(EXECS) *.o *.a
+
+# without .h => globals.o
+screencasts.a:globals.o print.o error.o fatal.o display.o 
+	ar -rcs screencasts.a $^

020/common.h

@@ -0,0 +1,27 @@
+/*  Poor man's approximation of PI */
+#define PI 3.1415926535898
+/*  Macro for sin & cos in degrees */
+#define Cos(th) cos(PI/180*(th))
+#define Sin(th) sin(PI/180*(th))
+/*  Determine number of elements in an array  */
+#define Length(x) (sizeof (x) / sizeof *(x))
+
+/*  Common #defines */
+/*  Defaults for window sizing  */
+#define DEF_WINDOW_HEIGHT 600
+#define DEF_WINDOW_WIDTH 700
+
+/*  Projection  */
+#define DEF_ASP 1
+#define DEF_DIM 5
+#define DEF_TH 340
+#define DEF_PH 30
+#define DEF_FOV 25
+#define DEF_ECX 0
+#define DEF_ECY 0
+#define DEF_ECZ 0
+
+/*  Draw defaults  */
+#define DEF_AXES 1
+#define DEF_PARAMS 1
+#define DEF_OVERLAY 0

020/display.c

@@ -0,0 +1,57 @@
+#include "screencasts.h"
+
+/*
+ *  displayReshape()
+ *  ------
+ *  GLUT calls this routine when the window is resized
+ */
+void displayReshape(int width,int height)
+{
+  asp = (height>0) ? (double)width/height : 1;
+  glViewport(0,0, width,height);
+  displayProject(fov,asp,dim);
+}
+
+/*
+ * displayProject()
+ * ------
+ * Sets the projection
+ */
+void displayProject(double fov, double asp, double dim)
+{
+  glMatrixMode(GL_PROJECTION);
+  glLoadIdentity();
+  // 2D only for this example
+  gluOrtho2D(-asp,+asp,-1,+1);
+  glMatrixMode(GL_MODELVIEW);
+  glLoadIdentity();
+}
+
+/*
+ *  display()
+ *  ------
+ *  Display the scene
+ */
+void display(void)
+{
+  /* setup functions */  
+  glClear(GL_COLOR_BUFFER_BIT);
+
+  /* Draw Scene */
+  drawScene();
+
+  /* Flush and sanity check */
+  glFlush();
+  errCheck("display sanity check");
+}
+
+/*
+ *  redisplayAll()
+ *  ------
+ *  This is called whenever we need to draw the display
+ */
+void redisplayAll(void)
+{
+  displayProject(fov,asp,dim);
+  glutPostRedisplay();
+}

020/display.h

@@ -0,0 +1,4 @@
+void displayReshape(int width,int height);
+void displayProject(double fov,double asp,double dim);
+void display(void);
+void redisplayAll(void);

020/error.c

@@ -0,0 +1,12 @@
+#include "screencasts.h"
+
+/*
+ * errCheck()
+ * ------
+ * Checks to see if there is an error and displays it if there was
+ */
+void errCheck(char* where)
+{
+  int err = glGetError();
+  if (err) fprintf(stderr,"ERROR: %s [%s]\n",gluErrorString(err),where);
+}

020/error.h

@@ -0,0 +1 @@
+void errCheck(char* where);

020/fatal.c

@@ -0,0 +1,15 @@
+#include "screencasts.h"
+
+/*
+ * fatal()
+ * ------
+ * Throws a fatal error and exits the program
+ */
+void fatal(const char* format , ...)
+{
+   va_list args;
+   va_start(args,format);
+   vfprintf(stderr,format,args);
+   va_end(args);
+   exit(1);
+}

020/fatal.h

@@ -0,0 +1 @@
+void fatal(const char* format , ...);

020/globals.c

@@ -0,0 +1,18 @@
+#include "screencasts.h"
+/*  ID-used to keep screencasts separate  */
+int screencastID = 0;
+
+/*  WINDOW  */
+char *windowName="OpenGL screenscasts XX: Placeholder";
+int windowHeight=DEF_WINDOW_HEIGHT;
+int windowWidth=DEF_WINDOW_WIDTH;
+
+/*  PROJECTION  */
+double asp=DEF_ASP;
+double dim=DEF_DIM;
+int th=DEF_TH;
+int ph=DEF_PH;
+int fov=DEF_FOV;
+double ecX=DEF_ECX;
+double ecY=DEF_ECY;
+double ecZ=DEF_ECZ;

020/print.c

@@ -0,0 +1,44 @@
+#include "screencasts.h"
+
+#define LEN 8192
+
+/*
+ * printv()
+ * ------
+ * Actually prints the characters
+ */
+void printv(va_list args, const char* format)
+{
+  char buf[LEN];
+  char* ch=buf;
+  vsnprintf(buf,LEN,format,args);
+  while (*ch)
+    glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18,*ch++);
+}
+
+/*
+ * print()
+ * ------
+ * Prints the words on screen
+ */
+void print(const char* format, ...)
+{
+  va_list args;
+  va_start(args,format);
+  printv(args,format);
+  va_end(args);
+}
+
+/*
+ * printAt()
+ * ------
+ * Prints the words at a given X-Y location on screen
+ */
+void printAt(int x, int y, const char* format, ...)
+{
+  va_list args;
+  glWindowPos2i(x,y);
+  va_start(args,format);
+  printv(args,format);
+  va_end(args);
+}

020/print.h

@@ -0,0 +1,3 @@
+void printv(va_list args, const char* format);
+void print(const char* format, ...);
+void printAt(int x, int y, const char* format, ...);

020/screencasts.h

@@ -0,0 +1,51 @@
+#ifndef SCREENCASTS
+#define SCREENCASTS
+
+/*  Standard headers  */
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+#include <math.h>
+#include <time.h>
+
+/*  OpenGL and friends  */
+#ifdef USEGLEW
+#include <GL/glew.h>
+#endif
+#define GL_GLEXT_PROTOTYPES
+#ifdef __APPLE__
+#include <GLUT/glut.h>
+#else
+#include <GL/glut.h>
+#endif
+
+/*  Includes  */
+#include "common.h"  /* common is just defines */
+#include "display.h" /* display -> setup scene to draw */
+
+/*  COMMON  */
+#include "error.h"   /* error convenience */
+#include "fatal.h"   /* fatal convenience */
+#include "print.h"   /* printing functions */
+
+/*  GLOBALS (externs required here)  */
+/*  Don't forget to initialize globals!  */
+extern int screencastID;
+
+/*  Window info  */
+extern char *windowName;
+extern int windowWidth;
+extern int windowHeight;
+
+/*  View  */
+extern double asp;/* aspect ratio */
+extern double dim;/* dimension of orthogonal box */
+extern int th;    /* azimuth of view angle */
+extern int ph;    /* elevation of view angle */
+extern int fov;   /* field of view for perspective */
+extern double ecX;      /* eye center position x */
+extern double ecY;      /* eye center position y */
+extern double ecZ;      /* eye center position z */
+
+#endif