CG Flashcards
Bresenham circle algorithm
x = 0, y=R
p = 3-2R
if p<0
x = x+1
y=y
p(i+1) = p + 4*x(i+1) + 6
if p>=0
x= x+1
y=y-1
p(i+1) = p + 4(xi+1 - yi+1) + 10
Bresenham line drawing algorithm
x = x1, y=y1
dx = x2-x1, dy= y2-y1
p = 2dx-dy
if p<0
x=x+1
y=y
p=p+2dy
else
x=x+1
y=y+1
p=p+2dy-2dx
DDA | Bresenham
floating point arithmetic
calculate slope, calculate dec par
accurate for high slopes, low slope
slower due to fl pt arithmetic
more alias artifacts for lines with high slopes
simple to implement
Rastar | Random
Electron beam scans entire screen
Low resolution
Cheaper
Scan conversion req
Video controller req
Dyanmic scene, Static scene
DDA algorithm
Digital Differential Analyzer
Incremental method where calculation performed at each step
dx = x2-x1
dy=y2=y1
if dx>dy
step = dx
yinc = dy/step xinc = dx/step
Significance of region codes
Set of numbers assigned to each pixel
Boundary
Fill
Region Adjacency
Region merging/splitting
Region compression
View transformation
xv - xvmin = xw - xwmin . Sx
Window and Viewport
Defines area of interest to be displayed
Defines the area on the display device where the rendered image will be displayed
OpenGL structure
cross platform, open structured, rendering graphics on platforms
1 API
2 OpenGL state
3 Pipeline
4 OpenGL context
OpenGl pipeline
Vertex processing
Primitive assembly
Rastarization
Fragment processing
Benefits of OpenGL
1 Hardware Independence
2 Flexibility: OpenGL provides a flexible way for applications to specify the graphics data
3 Efficiency: OpenGL provides an efficient way for applications to render graphics
4 Scalability: OpenGL provides a scalable way for applications to render graphics
OpenGL libraries
GLU
common utility tasks like setting up projects
GLUT
toolkit for rendering, creating windows
GLSL
shader tasks - small tasks run on the GPU
GLEW (Extention Wrangler)
cross platform library for accessing extensions
FreeGLUT
cross platform open source alternative
