e85d191b46
- merge v0.01 --> Añadido fileselector - Añadidas fuentes de Gem y Pure Data - pix2jpg incluído en Gem. Archivos de construcción de Gem modificados. - Añadido fichero ompiling.txt con instrucciones de compilación
115 lines
5.4 KiB
HTML
115 lines
5.4 KiB
HTML
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="Author" content="Mark Danks">
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<meta name="Author" content="IOhannes m zmölnig">
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<title>Basic Objects</title>
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</head>
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<body>
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<center>
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<h2>
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<u>Basic Objects</u></h2></center>
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<p><br>There are a number of objects which are the foundation for GEM.
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These objects are used in every patch and control the graphics and rendering.
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<p><a href="#gemwin">[gemwin]</a> - The window manager
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<br><a href="#gemhead">[gemhead]</a> - The start of a rendering chain
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<br><a href="#manips">manips</a> - Move an object in the window
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<br><a href="#geos">geos</a> - Render a shape
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<p><img SRC="tribar.gif" height=13 width=561>
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<h3>
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<a NAME="gemwin"></a>[gemwin]</h3>
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The graphics window is created and destroyed with the <i>[gemwin]</i> object.
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With the <i>[gemwin]</i> object, you can set the default size of the graphics
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window, create and destroy the graphics window, turn on and off rendering,
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etc. All basic GEM patches will have the following <i>[gemwin]</i>
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object with these messages:
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<center>
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<p><img SRC="gemwin.jpg" BORDER=1 height=128 width=78></center>
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The create and destroy messages will display and remove the graphics window.
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The 1 and 0 messages start and stop rendering.
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<p><img SRC="tribar.gif" height=13 width=561>
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<h3>
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<a NAME="gemhead"></a>[gemhead]</h3>
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The <i>[gemhead]</i> object is the start of every rendering chain.
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A simple patch, which is located in examples/gem_basic/gem1.redSquare.pd
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looks like:
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<center>
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<p><img SRC="redSquare.jpg" BORDER=1 height=138 width=91></center>
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<p>This patch will render a red square. The <i>[gemhead]</i> object
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signifies the start of rendering. The <i>[color]</i> object sets the color
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for all objects after it in the chain. The <i>[square]</i> object renders
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a square into the graphics window based on the current color, texturing,
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and transformations. In this case, there is no texturing and no transformation.
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<p>Every rendering chain <b>MUST</b> start with a [gemhead]. If you
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do not put a <i>[gemhead]</i> at the beginning of the chain, then nothing
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will be rendered for that part of the patch.
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<p><img SRC="tribar.gif" height=13 width=561>
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<h3>
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<a NAME="manips"></a>manips</h3>
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In the patch 01.basic/02.cube.pd, the <i>[translateXYZ]</i> object is
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introduced.
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<center>
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<p><img SRC="basicCube.jpg" BORDER=1 height=133 width=93></center>
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<p>The graphics are transformed and moved by the <i>manipulator</i> objects,
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or the manips. GEM has the following manips:
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<p><i>[color]</i> - set the color with a vector
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<br><i>[colorRGB]</i> - set the color with 3 discrete values
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<br><i>[rotate]</i> - rotate with an angle and vector
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<br><i>[rotateXYZ]</i> - rotate with 3 discrete values
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<br><i>[scale]</i> - scale with a vector
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<br><i>[scaleXYZ]</i> - scale with 3 discrete values
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<br><i>[translate]</i> - translate with a vector
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<br><i>[translateXYZ]</i> - translate with 3 discrete values
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<p>To understand the difference between the vector and discrete values
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version, realize that everything in is defined in 3 dimensions. These
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dimensions can be XYZ values, or RGB colors.
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<center>
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<p><img SRC="transXYZ.jpg" BORDER=1 height=92 width=201></center>
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<p>The two translate objects above will do exactly the same thing in a
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patch, but they provide two different ways to do it. <i>[translate]</i> accepts
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a scalar and vector. <i>[translateXYZ]</i> accepts three floats which
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specify a point in space. The manips will transform any object which
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appears after it in the rendering chain.
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<p><img SRC="tribar.gif" height=13 width=561>
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<h3>
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<a NAME="geos"></a>geos</h3>
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Up above, we saw the <i>[square]</i> and <i>[cube]</i> objects. The other
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primary geos are:
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<p><i>[square]</i> - render a square
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<br><i>[circle]</i> - render a circle
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<br><i>[triangle]</i> - render a triangle
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<br><i>[cube]</i> - render a cube
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<br><i>[sphere]</i> - render a sphere
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<br><i>[cone]</i> - render a cone
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<p>The <i>[square]</i>, <i>[circle]</i>, <i>[cube]</i>, and <i>[triangle]</i> objects
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have a right-hand inlet to set the size of the shape. The default
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size is 1.
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<p>The <i>[cone]</i> and <i>[sphere]</i> objects are not perfectly smooth.
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They are actually composed of a number of polygons. In order to control
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the rendering better, the middle inlet is the size of the object, while
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the right-hand inlet is the number of slices to define the shape.
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Take a look at the patch gem_basic/gem3.sphere.pd to see how the number
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of slices can change the look of a sphere. Don't worry about the
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<i><a href="Lighting.html#world_light">[world_light]</a></i>
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object, it is just there to make it easier to see the difference in the
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number of slices. Make sure to click the 'lighting 0' message before
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closing the patch (if you don't, then other patches will probably be completely
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black until you quit and restart pd/GEM).
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<p>Your graphics window should look like this for 5 and 15 slices:
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<center>
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<p><img SRC="sphere5.jpg" BORDER=0 height=150 width=150><img SRC="sphere15.jpg" height=150 width=150></center>
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Obviously, the more slices that you use, the better the sphere looks.
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However, each slice adds more polygons, which can slow down your frame
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rate. In computer graphics, there is always a trade off between resolution
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and speed.
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<p><img SRC="tribar.gif" height=13 width=561>
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<p><a href="index.html">[return]</a>
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<br>
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</body>
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</html>
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