# 0.7 Textures in processing

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A brief guide to texture mapping in Processing

## Color interpolation

As seen in Graphic Composition in Processing , one can obtain surfaces as collections of polygons by means of the definition of a vertexwithin the couple beginShape() - endShape() . It is possible to assign a color to one or more vertices, in order to make the color variations continuous ( gradient ). For example, you can try to run the code size(200,200,P3D);beginShape(TRIANGLE_STRIP); fill(240, 0, 0); vertex(20,31, 33);fill(240, 150, 0); vertex(80, 40, 38); fill(250, 250, 0); vertex(75, 88, 50);vertex(49, 85, 74); endShape(); in order to obtain a continuous nuance from red to yellow in the strip of two triangles.

## Bilinear interpolation

The graphical system performs an interpolation of color values assigned to the vertices. This type of bilinear interpolation is defined in the following way:

• For each polygon of the collection
• For each side of the polygon one assigns to each point on the segment the color obtained by means of linear interpolation of the colors of the vertices $i$ e $j$ that define the polygon: ${C}_{ij}(\alpha )=\left(1-\mathrm{\alpha \right)}{C}_{i}+\alpha {C}_{j}$
• A scan line scans the polygon (or, better, its projection on the image window) intersecting at each step two sides in two points $l$ ed $r$ whose colors have already been identified as ${C}_{l}$ e ${C}_{r}$ . In each point of the scan line the color is determined by linear interpolation ${C}_{lr}(\beta )=\left(1-\mathrm{\beta \right)}{C}_{l}+\beta {C}_{r}$

A significative example of interpolation of colors associated to the vertices of a cube can be found in examples of Processing , in the code RGB Cube .

## Texture

When modeling a complex scene by means of a composition of simple graphical elements one cannot go beyond a certainthreshold of complexity. Let us think about the example of a modelization of a natural scene, where one has to representeach single vegetal element, including the grass of a meadow. It is unconceivable to do this manually. It would bepossible to set and control the grass elements by means of some algorithms. This is an approach taken, for example, inrendering the hair and skin of characters of the most sophisticated animation movies (see for example, the Incredibles ). Otherwise, especially in case of interactive graphics, one has to resort to using textures . In other words, one employs images that represent the visual texture of the surfaces and map them onthe polygons that model the objects of the scene. In order to have a qualitative rendering of the surfaces it is necessaryto limit the detail level to fragments not smaller than one pixel and, thus, the texture mapping is inserted in the rendering chain at the rastering level of the graphic primitives, i.e. where one passes from a 3Dgeometric description to the illumination of the pixels on the display. It is at this level that the removal of thehidden surfaces takes place, since we are interested only in the visible fragments.

In Processing, a texture is defined within a block beginShape() - endShape() by means of the function texture() that has as unique parameter a variable of type PImage . The following calls to vertex() can contain, as last couple of parameters, the point of the texture correspondingto the vertex. In fact, each texture image is parameterized by means of two variables $u$ and $v$ , that can be referred directly to the line and column of a texel (pixel of a texture) or, alternatively, normalized between $0$ and $1$ , in such a way that one can ignore the dimension as well as the width and height of the texture itself. Themeaning of the parameters $u$ and $v$ is established by the command textureMode() with parameter IMAGE or NORMALIZED .

What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
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NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
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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.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
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Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
how did you get the value of 2000N.What calculations are needed to arrive at it
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