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diff --git a/guide-src/index.html b/guide-src/index.html index 0e765b4..e590fc7 100644 --- a/guide-src/index.html +++ b/guide-src/index.html @@ -1,118 +1,20 @@ ---- introduction +--- about -<h3>your first pugl</h3> +<h2>pugl</h2> +<i><b>p</b>ommicket's <b>u</b>tility for <b>gl</b> shaders</i> +<hr> <p> -when you load up pugl for the first time, you should be greeted with a “Buffer” widget. -try changing its “input” value to <code>.pos.x</code>. -<div> - <img src="ex-posx.png" alt=""> -</div> -you should see a nice gradient like this: <span style="display:inline-block;margin-right:1em;width:2em;height:1em;background-image:linear-gradient(90deg, #000,#000,#000,#fff);"></span> -here the color of each pixel is directly determined by its x coordinate. -specifically: <code>.pos.x</code> is −1 at the left side of the screen and +1 at the right side of the screen. -since the “Buffer” widget’s title is in <span style="color:yellow;font-weight:bold;">yellow</span>, -the pixel values will be drawn from it. 0 (or anything below 0) is black and 1 (or anything above 1) is white, -so we see a gradient from black to white starting from the center of the screen. + pugl is a tool that lets you create & share shaders without writing any code. </p> <p> -now let’s try something a little more interesting. try adding a “Multiply” widget (by searching for it or -selecting it from the “math” section). set the “a” input to <code>.pos.x</code> and the “b” input to -<code>.pos.y</code>. then click on the “Multiply” text to set it as the active widget. -<div> - <img src="ex-multiply.png" alt=""> -</div> -you should now see a more interesting pattern where two of the corners of the screen are -white, and the other two corners are black: <img src="output-multiply.png" style="height:1em;" alt=""> -</p> - -<h3>vectors</h3> - -<p> -well, black & white is pretty boring. let’s try making some colors! -one of the nice things about shaders is that they’re very good at dealing with <a href="https://en.wikipedia.org/wiki/Vector_%28mathematics_and_physics%29" target="_blank">vectors</a>. -there’s a lot of mathematical theory behind vectors, but for our purposes all that really matters is that a vector is a list of numbers (called <em>components</em>). -in shaders you basically only deal with vectors with 2 to 4 components (referred to as x, y, z, w). -in graphics programming, colors are represented as vectors with 3 components, <span style="color:#f00;">red</span>, -<span style="color:#0f0;">green</span>, and <span style="color:#22f;">blue</span>, which go from 0 to 1. -try putting <code>0,0.8,1</code> in a “Buffer” widget and making it active. -now the widget is outputting a vector with x=0, y=0.8, and z=1, so -you’ll get a nice <span style="color:#0cf">greenish blue</span> color! -</p> - -<p> -<code>.pos</code> is itself a vector, so you can just throw it into the Buffer input: -<div><img src="ex-vector.png" alt=""> <img src="output-vector.png" alt="" height="32"></div> -notice how the output is red on the right side of the screen (where the x component of <code>.pos</code> is high) -and green at the top of the screen (where the y component of <code>.pos</code> is high). -</p> - -<p> -most widgets like Multiply work on both numbers and vectors. try multiplying together -<code>.pos</code> and <code>.pos.x</code>: -<div><img src="ex-multiply-vector.png" alt=""> <img src="output-multiply-vector.png" alt="" height="32"></div> -this multiplies each of the components of <code>.pos</code> by <code>.pos.x</code>. -so the top-left corner is red, because (−1, 1) × −1 = (1, −1), so the top-left pixel gets a red value of 1 and a green value of −1. -</p> - -<h3>multiple widgets</h3> - -<p> -you can use the output of one widget to specify the input of another widget using its name. -try creating an “Add” widget with inputs <code>mul1,0</code> and <code>0,0,.pos.x</code> (assuming -your Multiply widget from the last section was called mul1). -<div><img src="ex-multiply-add.png" alt=""> <img src="output-multiply-add.png" alt="" height="32"></div> -now the left side looks the same as before, but the right side (where <code>.pos.x</code> is 1) is bluer! -</p> - -<h3>putting everything together</h3> - -<p> -alright let's use all this to make something cool. -we'll start by making a rainbow. -the “Hue shift” widget shifts the hue of a color through the rainbow. -so if we start with a color of red, and shift it by <code>.pos.x</code>, -we'll get a rainbow across the screen: -<div> -<img src="ex-hue-shift.png" alt=""> <img src="output-hue-shift.png" alt="" height="32"> -</div> -</p> - -<p> -now let's animate this rainbow: create a new “Add” widget, -and set a=<code>.pos.x</code>, b=<code>.time</code>, -and use that as the shift instead of <code>.pos.x</code>: -<div><img src="ex-hue-shift-time.png" alt=""></div> -now the rainbow moves across the screen over time! -</p> - -<p> -next we’ll use the widget that makes pugl unique ☺ -“Last frame”. this lets you grab pixel values from the previous frame -to use in the current frame. add a “Last frame” widget, -and set it as the active widget. notice how the rainbow freezes in place — -that’s because each pixel value is just being determined by what it was -on the last frame. -<div><img src="ex-last-frame.png" alt=""></div> + to learn how to use pugl, check out <a href="introduction.html">the next section</a>. </p> +<h3>credits</h3> +<hr> <p> -now add a “Weighted sum” widget, set “a weight” to 0.95, “b weight” to 0.05, -”a” to your last frame widget's output, and “b” to the hue shift's output. -this will output a value which is 95% like the previous frame's value, -and 5% like the shifting rainbow. -<div><img src="ex-weighted-sum.png" alt=""></div> -try switching between the “Hue shift” and “Weighted sum” widgets -and note how the weighted sum is blurrier, because it's averaging -with the previous pixel value. +icon based on +<a href="https://commons.wikimedia.org/wiki/File:Long-beakedEchidna.jpg" target="_blank">Long-beakedEchidna.jpg from WikiMedia</a> +CC BY-SA 3.0. </p> <p> -now, we don’t have to use <code>.pos</code> as the position for getting -pixel values from the last frame. instead, let’s rotate <code>.pos</code> -by a small amount and use that as the position for the “Last frame” widget: -<div><img src="ex-rotate-2d.png" alt=""> <img src="output-rotate-2d.png" alt=""></div> -now we’re getting something interesting! -</p> - -<p> -be sure to check out the rest of this guide to learn all the things -you can do with pugl. have fun! 🐱 -</p> +everything else is licensed under WTFPLv2. |