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Pills of opengl

OpenGL is a set of functions that allow the programmer to access the graphicsystem. Technically speaking, it is an Application Programming Interface (API) . Its main scope is the graphic rendering of a scene populated by 3D objects and lights, from a givenviewpoint. As far as the programmer is concerned, OpenGL allows to describe geometric objects and some of their properties, andto decide how such objects have to be illuminated and seen. As far as the implementation is concerned, OpenGL is based on the graphic pipeline , made of modules as reported in [link] . An excellent book on interactive graphics in OpenGL was written by Angel .

The opengl pipeline

In Processing (and in OpenGL), the programmer specifies the objects by means of world coordinates( standard coordinates ). The model-view matrix is the transformation matrix used to go from standard coordinates to a spaceassociated with the camera. This allows to change the camera viewpoint and orientation dynamically. In OpenGL this is donewith the function gluLookAt() , which is reproduced in Processing by the camera() . The first triple of parameters identifies the position, in worldcoordinates, of the optical center of the camera ( eye point ). The second triple of parameters identifies a point where the camera is looking at ( center of the scene ). The third triple of coordinates identifies a vector aimed at specifying the viewing vertical. For example,the program void setup() {size(100, 100, P3D); noFill();frameRate(20); }void draw() { background(204);camera(70.0, 35.0, 120.0, 50.0, 50.0, 0.0, (float)mouseX /width, (float)mouseY /height, 0.0);translate(50, 50, 0); rotateX(-PI/6);rotateY(PI/3); box(45);} draws the wireframe of a cube and enables the dynamic rotation of the camera.

The projection matrix is responsible for the projection on the viewing window, and this projection canbe either parallel (orthographic) or perspective. The orthographic projection can be activated with the call ortho() . The perspective projection is the default one, but it can be explicitly activated with the call perspective() . Particular projections, such as the oblique ones, can be obtained by distortion of objects byapplication of the applyMatrix() . There is also the texture matrix , but textures are treated in another module.

For each type of matrix, OpenGL keeps a stack, the current matrix being on top. The stack data structure allows to savethe state (by the pushMatrix() ) before performing new transformations, or to remove the current state andactivate previous states (by the popMatrix() ). This is reflected in the Processing operations described in [link] . In OpenGL, the transformations are applied according to the sequence

  1. Push on the stack;
  2. Apply all desired transformations by multiplying by thestack-top matrix;
  3. Draw the object (affected by transformations);
  4. Pop from the stack.

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Media processing in processing. OpenStax CNX. Nov 10, 2010 Download for free at http://cnx.org/content/col10268/1.14
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