Program 2 due 02/01Program 2 due 02/01

Be sure to document your programBe sure to document your program program level docprogram level doc

your nameyour name what the program doeswhat the program does

each functioneach function describe the argumentsdescribe the arguments describe what the function doesdescribe what the function does

document anything you may forget in a weekdocument anything you may forget in a week

Indexed ColorIndexed Color

Needed for frame buffers with a limited Needed for frame buffers with a limited depth depth 8 bits of color = 2**8 colors = 256 colors8 bits of color = 2**8 colors = 256 colors default is dividing bits into rbg assignmentsdefault is dividing bits into rbg assignments

load color map with a pallette of 256 load color map with a pallette of 256 colorscolors

LUTLUT

ViewingViewing

Camera and objects are specified Camera and objects are specified independently.independently.

For a 2D world - define viewing or clipping For a 2D world - define viewing or clipping rectangle.rectangle. Objects inside will be seen.Objects inside will be seen. Objects outside will not be seen.Objects outside will not be seen.

For a 3D world - define a viewing volume.For a 3D world - define a viewing volume. Orthographic projection.Orthographic projection.

Matrix ModesMatrix Modes

Pipeline graphics dependent on Pipeline graphics dependent on concatenating a number of concatenating a number of transformation matrices.transformation matrices.Vertices Transformer Clipper Projector Rasterizer PixelsVertices Transformer Clipper Projector Rasterizer Pixels

Matrices Matrices model-viewmodel-view projectionprojection

Clients and ServersClients and Servers

Graphics server Graphics server Workstation with raster display , keyboard, Workstation with raster display , keyboard,

and pointing deviceand pointing device Provides input and output services for Provides input and output services for

networknetwork

Client Client OpenGL application programsOpenGL application programs

Display ListsDisplay Lists

From display processor From display processor A special purpose computerA special purpose computer

Host computer sent instructions to the display processorHost computer sent instructions to the display processor Instructions stored in display memory as a display file or a Instructions stored in display memory as a display file or a

display listdisplay list

Immediate modeImmediate mode Program defines a primitiveProgram defines a primitive Primitive sent to server for displayPrimitive sent to server for display No memory of primitive existsNo memory of primitive exists

Display ListsDisplay Lists Retained mode graphicsRetained mode graphics

Define object onceDefine object once Put description in a display listPut description in a display list Display list stored on the serverDisplay list stored on the server Redisplayed by a single function callRedisplayed by a single function call AdvantageAdvantage

Reduced network trafficReduced network traffic DisadvantageDisadvantage

Memory required on the serverMemory required on the server Creating the display list has overheadCreating the display list has overhead

Display ListsDisplay Lists

Creation of a display list - use glNewList, Creation of a display list - use glNewList, glEndList to encapsulate the list.glEndList to encapsulate the list.

Each list has an int identifier which can be Each list has an int identifier which can be invoked with the command glCallList(identifier);invoked with the command glCallList(identifier);

Save attributes with the matrix and attribute Save attributes with the matrix and attribute stacks (remember from 202: push onto a stack stacks (remember from 202: push onto a stack and pop off of a stack).and pop off of a stack).

InteractionInteraction

According to Webster’sAccording to Webster’s To act upon each otherTo act upon each other

Two way communicationTwo way communication GLUT toolkit for windowingGLUT toolkit for windowing GLUT recognizes only a small subset of GLUT recognizes only a small subset of

the events recognized by X the events recognized by X

InputInput

Input devicesInput devices Logical devicesLogical devices

From the perspective of the application programFrom the perspective of the application program

Physical devicesPhysical devices Hardware and how it worksHardware and how it works

Input ModesInput Modes

Mode defined by the relationship between the Mode defined by the relationship between the trigger and the measuring process.trigger and the measuring process. Trigger (physical input that user signals computer).Trigger (physical input that user signals computer). Measure (what is returned to the program).Measure (what is returned to the program).

Request mode.Request mode. Measure returned when triggered.Measure returned when triggered.Trigger Trigger measuremeasure request request program.program.

Process triggerProcess trigger process measure.process measure.

Input ModesInput Modes

Sample modeSample mode Measure returned when triggeredMeasure returned when triggered

MeasureMeasure samplesample programprogramProcess Process measuremeasure

Event modeEvent mode Device triggeredDevice triggered Event generatedEvent generated Device measure placed on the event queueDevice measure placed on the event queue Event type tied to function called CALLBACK Event type tied to function called CALLBACK

Input ModesInput Modes

Trigger Trigger measure measure event event await program.await program.

Process trigger process measure queue Process trigger process measure queue event.event.

Event mode.Event mode. Device triggered.Device triggered. Event generated.Event generated. Device measure placed on the event queue.Device measure placed on the event queue. CALLBACK registered with the windowing system. CALLBACK registered with the windowing system.

Event type tied to function called a callback.Event type tied to function called a callback.

Using the Pointing Device Using the Pointing Device MMouse Triggered Eventsouse Triggered Events

Move eventMove event Move the mouse with the buttons depressedMove the mouse with the buttons depressed

Passive move eventPassive move event Move the mouse without pressing a buttonMove the mouse without pressing a button

Mouse eventMouse event When one of the buttons is either released When one of the buttons is either released

or pressedor pressed

Specify the Mouse Specify the Mouse Callback FunctionCallback Function

InIn main()main()

With With glutMouseFunc(mouse_callback_func)glutMouseFunc(mouse_callback_func) void mouse_callback_func(int button, int void mouse_callback_func(int button, int state, int x, int, y)state, int x, int, y)

The callback function specifies what actions The callback function specifies what actions are related to the specified eventare related to the specified event

Window EventWindow Event

Generated when the window is resized Generated when the window is resized Redraw all the objects in the windowRedraw all the objects in the window How to handle the aspect ratioHow to handle the aspect ratio Do we change the sizes or attributes of the Do we change the sizes or attributes of the

new primitives if the size of the new window new primitives if the size of the new window is different from that of the oldis different from that of the old

Keyboard EventsKeyboard Events

Generated when the mouse is in the Generated when the mouse is in the window and one of the keys is depressedwindow and one of the keys is depressed

Returns the ascii code for the key and Returns the ascii code for the key and the x and y coordinates of thethe x and y coordinates of the mouse mouse

void keyboard(unsigned char key, int x, void keyboard(unsigned char key, int x, imt y)imt y)

Display CallbackDisplay Callback

Invoked when GLUT determines the Invoked when GLUT determines the window should be redisplayedwindow should be redisplayed Upon opening it initiallyUpon opening it initially

Idle FunctionIdle Function

Idle callback invoked when there are no other Idle callback invoked when there are no other events.events. Generates graphical primitives through a display Generates graphical primitives through a display

function while nothing else is happening.function while nothing else is happening. Event processing happens between calls to the idle Event processing happens between calls to the idle

function.function. Do not spend too much time in the idle function.Do not spend too much time in the idle function.

Idle does not actually rerender the frame.Idle does not actually rerender the frame. To rerender callTo rerender call glutPostRedisplay();glutPostRedisplay(); from from

within the idle callback.within the idle callback.

MenusMenus

GLUT provides popup menusGLUT provides popup menus glutCreateMenu(menu_callback_name);glutCreateMenu(menu_callback_name);

Menu_callback_name is the name of the Menu_callback_name is the name of the function. The argument to that function is the function. The argument to that function is the identifier passed to the callback when the entry isidentifier passed to the callback when the entry is selectedselected

Adding a MenuAdding a Menu

glutCreateMenuglutCreateMenu

(menu_callback_name);(menu_callback_name);

glutAddMenuEntry("quit",1);glutAddMenuEntry("quit",1);

glutAttachMenuglutAttachMenu

(GLUT_RIGHT_BUTTON);(GLUT_RIGHT_BUTTON);

Adding a menu callbackAdding a menu callback

menu_callback_name(int id)menu_callback_name(int id)

{{

if (id == .if (id == .

..

..

}}

AnimationAnimation

Double buffering eliminates flicker.Double buffering eliminates flicker.

Callback Advice From the Callback Advice From the Creator of GLUT, Mark Creator of GLUT, Mark KilgardKilgard

Don’t change state that will affect the way a Don’t change state that will affect the way a window will be drawn a display callback. window will be drawn a display callback.

If you need to redisplay a window, instead of If you need to redisplay a window, instead of rendering in whatever callback you happen to rendering in whatever callback you happen to be in, call glutPostRedisplay.be in, call glutPostRedisplay.

If you use an idle callback to control animation, If you use an idle callback to control animation, use a visibility callback to determine when the use a visibility callback to determine when the window is fully obscured or iconified.window is fully obscured or iconified.

More Callback AdviceMore Callback Advice

The backspace, Esc, and Del keys The backspace, Esc, and Del keys generate ASCII characters, so detect key generate ASCII characters, so detect key presses for these keys using the presses for these keys using the glutKeyboardFuncglutKeyboardFunc callback. callback.

Design of InteractiveDesign of Interactive ProgramsPrograms

A smooth display (no flicker or artifacts of the refresh A smooth display (no flicker or artifacts of the refresh process)process)

A variety of interactive devices on the displayA variety of interactive devices on the display A variety of methods for entering and displaying A variety of methods for entering and displaying

informationinformation An easy to use interface that does not require An easy to use interface that does not require

substantial effort to learnsubstantial effort to learn Feedback to the userFeedback to the user Tolerance for user errorsTolerance for user errors A design incorporation for consideration of both the A design incorporation for consideration of both the

visual and motor properties of the humanvisual and motor properties of the human

Limitations of Geometric RenderingLimitations of Geometric Rendering

Designing widgetsDesigning widgets example of popup menuexample of popup menu refreshing the display where the menu wasrefreshing the display where the menu was no primitives but uses scan line image datano primitives but uses scan line image data

operations described in terms of the frame buffer operations described in terms of the frame buffer or in terms of bit-block transferor in terms of bit-block transfer operationoperation

Limitations of GeometricLimitations of Geometric RenderingRendering

RubberbandingRubberbanding a technique for displaying line segments in a a technique for displaying line segments in a

changing manner. changing manner. Endpoint is selected Endpoint is selected Before second endpoint is selected a line Before second endpoint is selected a line

segment is drawn automatically to where the segment is drawn automatically to where the present position of the mouse ispresent position of the mouse is

As the mouse moves the old segment must be As the mouse moves the old segment must be erased and a new one drawn.erased and a new one drawn.

HomeworkHomework

Read chapter 4 Read chapter 4 Program 2 due 02/01/05Program 2 due 02/01/05