The document describes code for a 3D graphics application using OpenGL and RingFreeGLUT. It includes functions for rendering a scene with 9 snowmen on a ground plane, handling user input for camera movement and rotation, and displaying frames per second. Keyboard, mouse, and menu callbacks are defined to control movement, rotation, and settings like polygon mode, color, and font. The main function initializes GLUT, registers the callbacks, and enters the event loop.

1. Ring Documentation, Release 1.6
x += deltaMove * lx * 0.1
z += deltaMove * lz * 0.1
func renderScene
if deltaMove
computePos(deltaMove)
ok
// Clear Color and Depth Buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
// Reset transformations
glLoadIdentity()
// Set the camera
gluLookAt( x, 1.0, z,
x+lx, 1.0, z+lz,
0.0, 1.0, 0.0)
// Draw ground
glColor3f(0.9, 0.9, 0.9)
glBegin(GL_QUADS)
glVertex3f(-100.0, 0.0, -100.0)
glVertex3f(-100.0, 0.0, 100.0)
glVertex3f( 100.0, 0.0, 100.0)
glVertex3f( 100.0, 0.0, -100.0)
glEnd()
// Draw 9 SnowMen
for i = -3 to -1
for j = -3 to -1
glPushMatrix()
glTranslatef(i*10.0, 0.0, j * 10.0)
drawSnowMan()
number = (i+3)*3+(j+3)
renderBitmapString(0.0, 0.5, 0.0,font ,""+number)
glPopMatrix()
next
next
// Code to compute frames per second
frame++
time=glutGet(GLUT_ELAPSED_TIME)
if time - timebase > 1000
s = "RingFreeGLUT - FPS: " + (frame*1000.0/(time-timebase))
timebase = time
frame = 0
ok
// Code to display a string (fps) with bitmap fonts
setOrthographicProjection()
glPushMatrix()
glLoadIdentity()
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renderBitmapString(5,30,0,GLUT_BITMAP_HELVETICA_18,s)
glPopMatrix()
restorePerspectiveProjection()
glutSwapBuffers()
// -----------------------------------
// KEYBOARD
// -----------------------------------
func processNormalKeys
key = glutEventKey()
xx = glutEventX()
yy = glutEventY()
switch key
on 27
glutDestroyMenu(mainMenu)
glutDestroyMenu(fillMenu)
glutDestroyMenu(colorMenu)
glutDestroyMenu(fontMenu)
Shutdown()
off
func pressKey
key = glutEventKey()
xx = glutEventX()
yy = glutEventY()
switch key
on GLUT_KEY_UP
deltaMove = 0.5
on GLUT_KEY_DOWN
deltaMove = -0.5
off
func releaseKey
key = glutEventKey()
switch key
on GLUT_KEY_UP
deltaMove = 0
on GLUT_KEY_DOWN
deltaMove = 0
off
// -----------------------------------
// MOUSE
// -----------------------------------
func mouseMove
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xx = glutEventX()
yy = glutEventY()
// this will only be true when the left button is down
if xOrigin >= 0
// update deltaAngle
deltaAngle = (xx - xOrigin) * 0.001
// update camera's direction
lx = sin(angle + deltaAngle)
lz = -cos(angle + deltaAngle)
ok
func mouseButton
button = glutEventButton()
state = glutEventState()
xx = glutEventX()
yy = glutEventY()
// only start motion if the left button is pressed
if button = GLUT_LEFT_BUTTON
// when the button is released
if state = GLUT_UP
angle += deltaAngle
xOrigin = -1
else
// state = GLUT_DOWN
xOrigin = xx
ok
ok
// -----------------------------------
// MENUS
// -----------------------------------
func processMenuStatus
status = glutEventStatus()
if status = GLUT_MENU_IN_USE
menuFlag = 1
else
menuFlag = 0
ok
func processMainMenu
// nothing to do in here
// all actions are for submenus
func processFillMenu
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option = glutEventValue()
switch option
on C_FILL
glPolygonMode(GL_FRONT, GL_FILL)
on C_LINE
glPolygonMode(GL_FRONT, GL_LINE)
off
func processFontMenu
option = glutEventValue()
switch (option) {
on C_INT_GLUT_BITMAP_8_BY_13
font = GLUT_BITMAP_8_BY_13
on C_INT_GLUT_BITMAP_9_BY_15
font = GLUT_BITMAP_9_BY_15
on C_INT_GLUT_BITMAP_TIMES_ROMAN_10
font = GLUT_BITMAP_TIMES_ROMAN_10
on C_INT_GLUT_BITMAP_TIMES_ROMAN_24
font = GLUT_BITMAP_TIMES_ROMAN_24
on C_INT_GLUT_BITMAP_HELVETICA_10
font = GLUT_BITMAP_HELVETICA_10
on C_INT_GLUT_BITMAP_HELVETICA_12
font = GLUT_BITMAP_HELVETICA_12
on C_INT_GLUT_BITMAP_HELVETICA_18
font = GLUT_BITMAP_HELVETICA_18
off
func processColorMenu
option = glutEventValue()
switch option
on C_RED
red = 1.0
green = 0.0
blue = 0.0
on C_GREEN
red = 0.0
green = 1.0
blue = 0.0
on C_BLUE
red = 0.0
green = 0.0
blue = 1.0
on C_ORANGE
red = 1.0
green = 0.5
blue = 0.5
off
func createPopupMenus
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fontMenu = glutCreateMenu(:processFontMenu)
glutAddMenuEntry("BITMAP_8_BY_13 ",C_INT_GLUT_BITMAP_8_BY_13 )
glutAddMenuEntry("BITMAP_9_BY_15",C_INT_GLUT_BITMAP_9_BY_15 )
glutAddMenuEntry("BITMAP_TIMES_ROMAN_10 ",C_INT_GLUT_BITMAP_TIMES_ROMAN_10 )
glutAddMenuEntry("BITMAP_TIMES_ROMAN_24",C_INT_GLUT_BITMAP_TIMES_ROMAN_24 )
glutAddMenuEntry("BITMAP_HELVETICA_10 ",C_INT_GLUT_BITMAP_HELVETICA_10 )
glutAddMenuEntry("BITMAP_HELVETICA_12",C_INT_GLUT_BITMAP_HELVETICA_12 )
glutAddMenuEntry("BITMAP_HELVETICA_18",C_INT_GLUT_BITMAP_HELVETICA_18 )
fillMenu = glutCreateMenu(:processFillMenu)
glutAddMenuEntry("Fill",C_FILL)
glutAddMenuEntry("Line",C_LINE)
colorMenu = glutCreateMenu(:processColorMenu)
glutAddMenuEntry("Red",C_RED);
glutAddMenuEntry("Blue",C_BLUE);
glutAddMenuEntry("Green",C_GREEN);
glutAddMenuEntry("Orange",C_ORANGE);
mainMenu = glutCreateMenu(:processMainMenu)
glutAddSubMenu("Polygon Mode", fillMenu)
glutAddSubMenu("Color", colorMenu)
glutAddSubMenu("Font",fontMenu)
// attach the menu to the right button
glutAttachMenu(GLUT_RIGHT_BUTTON)
// this will allow us to know if the menu is active
glutMenuStatusFunc(:processMenuStatus)
// -----------------------------------
// MAIN
// -----------------------------------
func main
// init GLUT and create window
glutInit()
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA)
glutInitWindowPosition(100,100)
glutInitWindowSize(320,320)
glutCreateWindow("RingFreeGLUT - Test - 9 SnowMan")
// register callbacks
glutDisplayFunc(:renderScene)
glutReshapeFunc(:changeSize)
glutIdleFunc(:renderScene)
glutIgnoreKeyRepeat(1)
glutKeyboardFunc(:processNormalKeys)
glutSpecialFunc(:pressKey)
glutSpecialUpFunc(:releaseKey)
// here are the two new functions
glutMouseFunc(:mouseButton)
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glutMotionFunc(:mouseMove)
// OpenGL init
glEnable(GL_DEPTH_TEST)
glEnable(GL_CULL_FACE)
// init Menus
createPopupMenus()
// enter GLUT event processing cycle
glutMainLoop()
Screen Shots:
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5.11 RingOpenGL Extension
Ring 1.5 comes with RingOpenGL and support for the next versions
• OpenGL 1.1
• OpenGL 1.2
• OpenGL 1.3
• OpenGL 1.4
• OpenGL 1.5
• OpenGL 2.0
• OpenGL 2.1
• OpenGL 3.0
• OpenGL 3.2
• OpenGL 3.3
• OpenGL 4.0
• OpenGL 4.1
• OpenGL 4.2
• OpenGL 4.3
• OpenGL 4.4
• OpenGL 4.5
• OpenGL 4.6
Example:
/*
This sample is based on C Tutorials
from :
http://www.wikihow.com/Make-a-Cube-in-OpenGL
*/
load "freeglut.ring"
load "opengl21lib.ring"
// ----------------------------------------------------------
// Global Variables
// ----------------------------------------------------------
rotate_y=0
rotate_x=0
// ----------------------------------------------------------
// display() Callback function
// ----------------------------------------------------------
func display
// Clear screen and Z-buffer
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)
// Reset transformations
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glLoadIdentity()
// Rotate when user changes rotate_x and rotate_y
glRotatef( rotate_x, 1.0, 0.0, 0.0 )
glRotatef( rotate_y, 0.0, 1.0, 0.0 )
//Multi-colored side - FRONT
glBegin(GL_POLYGON)
glColor3f( 1.0, 0.0, 0.0 ) glVertex3f( 0.5, -0.5, -0.5 ) # P1 is red
glColor3f( 0.0, 1.0, 0.0 ) glVertex3f( 0.5, 0.5, -0.5 ) # P2 is green
glColor3f( 0.0, 0.0, 1.0 ) glVertex3f( -0.5, 0.5, -0.5 ) # P3 is blue
glColor3f( 1.0, 0.0, 1.0 ) glVertex3f( -0.5, -0.5, -0.5 ) # P4 is purple
glEnd()
// White side - BACK
glBegin(GL_POLYGON)
glColor3f( 1.0, 1.0, 1.0 )
glVertex3f( 0.5, -0.5, 0.5 )
glVertex3f( 0.5, 0.5, 0.5 )
glVertex3f( -0.5, 0.5, 0.5 )
glVertex3f( -0.5, -0.5, 0.5 )
glEnd()
// Purple side - RIGHT
glBegin(GL_POLYGON)
glColor3f( 1.0, 0.0, 1.0 )
glVertex3f( 0.5, -0.5, -0.5 )
glVertex3f( 0.5, 0.5, -0.5 )
glVertex3f( 0.5, 0.5, 0.5 )
glVertex3f( 0.5, -0.5, 0.5 )
glEnd()
// Green side - LEFT
glBegin(GL_POLYGON)
glColor3f( 0.0, 1.0, 0.0 )
glVertex3f( -0.5, -0.5, 0.5 )
glVertex3f( -0.5, 0.5, 0.5 )
glVertex3f( -0.5, 0.5, -0.5 )
glVertex3f( -0.5, -0.5, -0.5 )
glEnd()
// Blue side - TOP
glBegin(GL_POLYGON)
glColor3f( 0.0, 0.0, 1.0 )
glVertex3f( 0.5, 0.5, 0.5 )
glVertex3f( 0.5, 0.5, -0.5 )
glVertex3f( -0.5, 0.5, -0.5 )
glVertex3f( -0.5, 0.5, 0.5 )
glEnd()
// Red side - BOTTOM
glBegin(GL_POLYGON)
glColor3f( 1.0, 0.0, 0.0 )
glVertex3f( 0.5, -0.5, -0.5 )
glVertex3f( 0.5, -0.5, 0.5 )
glVertex3f( -0.5, -0.5, 0.5 )
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glVertex3f( -0.5, -0.5, -0.5 )
glEnd()
glFlush()
glutSwapBuffers()
// ----------------------------------------------------------
// specialKeys() Callback Function
// ----------------------------------------------------------
func specialKeys
key = glutEventKey()
// Right arrow - increase rotation by 5 degree
switch Key
on GLUT_KEY_RIGHT
rotate_y += 5
// Left arrow - decrease rotation by 5 degree
on GLUT_KEY_LEFT
rotate_y -= 5
on GLUT_KEY_UP
rotate_x += 5
on GLUT_KEY_DOWN
rotate_x -= 5
off
// Request display update
glutPostRedisplay()
// ----------------------------------------------------------
// main() function
// ----------------------------------------------------------
func main
// Initialize GLUT and process user parameters
glutInit()
// Request double buffered true color window with Z-buffer
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
// Create window
glutCreateWindow("Awesome Cube")
// Enable Z-buffer depth test
glEnable(GL_DEPTH_TEST)
// Callback functions
glutDisplayFunc(:display)
glutSpecialFunc(:specialKeys)
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// Pass control to GLUT for events
glutMainLoop()
// Return to OS
Screen Shot:
5.12 Better Code Generator for Extensions
The Code Generator is updated to support <constant> type, So we can have constants other than numbers, for example
: Strings and Pointers.
When we have pointers we can determine the pointer type. To use this feature, before <constant> and </constant> we
can use
$nDefaultConstantType = C_CONSTANT_TYPE_POINTER
$cDefaultConstantPointerType = "void *"
The next example from the RingFreeGLUT extension
<runcode>
$nDefaultConstantType = C_CONSTANT_TYPE_POINTER
$cDefaultConstantPointerType = "void"
</runcode>
<constant>
GLUT_STROKE_ROMAN
GLUT_STROKE_MONO_ROMAN
GLUT_BITMAP_9_BY_15
GLUT_BITMAP_8_BY_13
GLUT_BITMAP_TIMES_ROMAN_10
GLUT_BITMAP_TIMES_ROMAN_24
GLUT_BITMAP_HELVETICA_10
GLUT_BITMAP_HELVETICA_12
5.12. Better Code Generator for Extensions 72