<< Chapter < Page Chapter >> Page >

In the code that follows the image representing a broken glass is employed as texture and followed by a color interpolationand the default illumination. The shading of the surfaces, produced by means of the illumination and the colors, ismodulated in a multiplicative way by the colors of the texture. size(400,400,P3D); PImage a = loadImage("vetro.jpg");lights(); textureMode(NORMALIZED);beginShape(TRIANGLE_STRIP); texture(a);fill(240, 0, 0); vertex(40,61, 63, 0, 0); fill(240, 150, 0); vertex(340, 80, 76, 0, 1);fill(250, 250, 0); vertex(150, 176, 100, 1, 1); vertex(110, 170, 180, 1, 0);endShape();

Got questions? Get instant answers now!

Texture mapping

It is evident that the mapping operations from a texture image to an object surface, of arbitrary shape, implies some formof interpolation. Similarly to what happens for colors, only the vertices that delimit the surface are mapped onto exactpoints of the texture image. What happens for the internal points has to be established in some way. Actually,Processing and OpenGL behave according to what illustrated in [link] , i.e. by bilinear interpolation: a first linear interpolation over eachboundary segment is cascaded by a linear interpolation on a scan line. If u and v exceed the limits of the texture image, the system (Processing) can assume that this isrepeated periodically and fix it to the values at the border.

A problem that occurs is that a pixel on a display does not necessarly correspond exactly to a texel. One can map morethan one texel on a pixel or, viceversa, a texel can be mapped on several pixels. The first case corresponds to adownsampling that, as seen in Sampling and Quantization , can produce aliasing. The effect of aliasing can be attenuated by means of low pass filtering ofthe texture image. The second case corresponds to upsampling, that in the frequency domain can be interpreted asincreasing the distance between spectral images.

Texture generation

Textures are not necessarely imported from images, but they can also be generated in an algorithmic fashion. This isparticularly recommended when one wants to generate regular or pseudo-random patterns. For example, the pattern of achess-board can be generated by means of the code PImage textureImg = loadImage("vetro.jpg"); // dummy image colorMode(RGB,1);int biro = 0; int bbiro = 0;int scacco = 5; for (int i=0; i<textureImg.width; i+=scacco) { bbiro = (bbiro + 1)%2; biro = bbiro;for (int j=0; j<textureImg.height; j+=scacco) { for (int r=0; r<scacco; r++) for (int s=0; s<scacco; s++) textureImg.set(i+r,j+s, color(biro));biro = (biro + 1)%2; }} image(textureImg, 0, 0);

The use of the function random, combined with filters of various type, allows a wide flexibility in the production oftextures. For example, the pattern represented in [link] was obtained from a modification of the code generating the chess-board. In particular, we added theline scacco=floor(2+random(5)); within the outer for , and applied an averaging filter.

Algorithmically-generated pattern

How could one modify the code [link] in order to make the breaks in the glass more evident?

It is sufficient to consider only a piece of the texture, with calls of the type vertex(150, 176, 0.3, 0.3);

Got questions? Get instant answers now!

The excercise consists in modifying the code of the generator of the chess-board in [link] in order to generate the texture [link] .

Got questions? Get instant answers now!

This exercise consists in running and analyzing the following code. Try then to vary the dimensions of the smallsquares and the filtering type. size(200, 100, P3D);PImage textureImg = loadImage("vetro.jpg"); // dummy image colorMode(RGB,1);int biro = 0; int bbiro = 0;int scacco = 5; for (int i=0; i<textureImg.width; i+=scacco) { // scacco=floor(2+random(5));bbiro = (bbiro + 1)%2; biro = bbiro; for (int j=0; j<textureImg.height; j+=scacco) { for (int r=0; r<scacco; r++) for (int s=0; s<scacco; s++) textureImg.set(i+r,j+s, color(biro));biro = (biro + 1)%2; }} image(textureImg, 0, 0);textureMode(NORMALIZED); beginShape(QUADS);texture(textureImg); vertex(20, 20, 0, 0);vertex(80, 25, 0, 0.5); vertex(90, 90, 0.5, 0.5);vertex(20, 80, 0.5, 0); endShape();// ------ filtering ------- PImage tImg = loadImage("vetro.jpg"); // dummy imagefloat val = 1.0/9.0; float[][] kernel = { {val, val, val},{val, val, val}, {val, val, val} };int n2 = 1; int m2 = 1;colorMode(RGB,255); // Convolve the imagefor(int y=0; y<textureImg.height; y++) { for(int x=0; x<textureImg.width/2; x++) { float sum = 0;for(int k=-n2; k<=n2; k++) { for(int j=-m2; j<=m2; j++) { // Reflect x-j to not exceed array boundaryint xp = x-j; int yp = y-k;if (xp<0) { xp = xp + textureImg.width;} else if (x-j>= textureImg.width) { xp = xp - textureImg.width;} // Reflect y-k to not exceed array boundaryif (yp<0) { yp = yp + textureImg.height;} else if (yp>= textureImg.height) { yp = yp - textureImg.height;} sum = sum + kernel[j+m2][k+n2] * red(textureImg.get(xp,yp)); }} tImg.set(x,y, color(int(sum)));} }translate(100, 0);beginShape(QUADS); texture(tImg);vertex(20, 20, 0, 0); vertex(80, 25, 0, 0.5);vertex(90, 90, 0.5, 0.5); vertex(20, 80, 0.5, 0);endShape();

Got questions? Get instant answers now!

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
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
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Media processing in processing. OpenStax CNX. Nov 10, 2010 Download for free at http://cnx.org/content/col10268/1.14
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Media processing in processing' conversation and receive update notifications?