Discrete TechniquesDiscrete Techniques

Chapter 7Chapter 7

Begun February 22, 2005Begun February 22, 2005

Finished April 26, 2005 Finished April 26, 2005

BuffersBuffers

Frame buffer consists of Frame buffer consists of Front color bufferFront color buffer Back color bufferBack color buffer Depth bufferDepth buffer

Each buffer has the dimensions (Each buffer has the dimensions (nn x x mm) of the ) of the display window.display window.

The depth (The depth (kk) of each buffer can vary. For RGB, ) of each buffer can vary. For RGB, it would be the number of bits per color X 3 it would be the number of bits per color X 3 colors. colors.

Bitplane refers to any of the Bitplane refers to any of the k nk n x x mm planes. planes.

Digital ImagesDigital Images

Glubyte myColorImage [512][512]Glubyte myColorImage [512][512][3];[3];

Glubyte myGrayImage [512][512];Glubyte myGrayImage [512][512]; Glubyte myLUTImage [512][512], Glubyte myLUTImage [512][512], red[256], green[256], red[256], green[256], blue[256];blue[256];

Creating Digital ImagesCreating Digital Images

With an algorithm.With an algorithm. From data.From data. From standard image formats.From standard image formats.

GIFGIF TIFFTIFF PSPS EPSEPS JPEGJPEG OpenGL does not support image formats.OpenGL does not support image formats.

From graphics system.From graphics system.

Writing Into BuffersWriting Into Buffers

Bitblt write operationBitblt write operation Write_block(Write_block(

source /* buffer */,source /* buffer */, n /* nrows */, n /* nrows */, m /* ncols */, m /* ncols */, x /* lower left x pos */,x /* lower left x pos */, y /* lower left y pos */,y /* lower left y pos */, destination /* buffer */, destination /* buffer */, u /* destination pos x */, u /* destination pos x */, v /* destination pos y */);v /* destination pos y */);

Writing ModesWriting Modes

Define writeDefine write Simple assignmentSimple assignment

x1 = x2x1 = x2

Replacement functionReplacement function d = f(d, s)d = f(d, s)

Writing With XORWriting With XOR

Most interesting functionMost interesting function Painting ApplicationPainting Application

S S S xor M S xor M M M S xor M S xor M S S S xor M S xor M

Bit and Pixel Operations in Bit and Pixel Operations in OpenGLOpenGL

Defines an internal cursorDefines an internal cursor glRasterPos3f(x, y, z);glRasterPos3f(x, y, z); glBitmap(width, /* # bits wide */glBitmap(width, /* # bits wide */

height, /* # bits high */height, /* # bits high */x0, /*offset from current x0, /*offset from current

raster position */raster position */y0, /* offset from current y0, /* offset from current

rster position */rster position */xi, /* x increment */xi, /* x increment */

Xy, /* y increment */Xy, /* y increment */

Raster FontsRaster Fonts

Pixels and ImagesPixels and Images

Lookup TablesLookup Tables

Buffers for PickingBuffers for Picking

Mapping MethodsMapping Methods

Texture MappingTexture Mapping

2D Texture Mapping2D Texture Mapping

Texture Mapping in OpenGLTexture Mapping in OpenGL

Texture Objects and Texture Objects and MultitexturingMultitexturing

Texture GenerationTexture Generation

Environmental MapsEnvironmental Maps

Bump MapsBump Maps

Compositing TechniquesCompositing Techniques

Opacity and BlendingOpacity and Blending

Image CompositingImage Compositing

Blending and Compositing in Blending and Compositing in OpenGLOpenGL

AntialiasingAntialiasing

Back-to-front and Front-to-Back-to-front and Front-to-back Renderingback Rendering

Depth Cue and FogDepth Cue and Fog

Multirendering and the Multirendering and the Accumulation BufferAccumulation Buffer

Scene AntialiasingScene Antialiasing

Bump Mapping and Bump Mapping and EmbossingEmbossing

Image ProcessingImage Processing

Image ExtensionsImage Extensions

Other Multipass MethodsOther Multipass Methods

Sampling and AntialiasingSampling and Antialiasing

Sampling TheorySampling Theory

ReconstructionReconstruction

QuantizationQuantization

Each sample must be quantized into k Each sample must be quantized into k discrete levels.discrete levels. Analog Scale - whole number of lbsAnalog Scale - whole number of lbs Image - pixel colorImage - pixel color

Binary image - two colors, b/wBinary image - two colors, b/w

Program 4Program 4

Due March 3, 2005Due March 3, 2005 Documentation 10%Documentation 10% Style 10%Style 10% Compiles 30%Compiles 30% Graphic Output 10%Graphic Output 10%