From c7b9db0d1bf3ae55c7e70207c636ced8606902ec Mon Sep 17 00:00:00 2001 From: pommicket Date: Wed, 6 Sep 2023 22:40:08 -0400 Subject: add some more widgets, cleanup --- guide-src/introduction.html | 118 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 guide-src/introduction.html (limited to 'guide-src/introduction.html') diff --git a/guide-src/introduction.html b/guide-src/introduction.html new file mode 100644 index 0000000..5dd2bdc --- /dev/null +++ b/guide-src/introduction.html @@ -0,0 +1,118 @@ +--- introduction + +

your first pugl

+

+when you load up pugl for the first time, you should be greeted with a “Buffer” widget. +try changing its “input” value to .pos.x. +

+ +
+you should see a nice gradient like this: +here the color of each pixel is directly determined by its x coordinate. +specifically: .pos.x 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 yellow, +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. +

+

+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 .pos.x and the “b” input to +.pos.y. then click on the “Multiply” text to set it as the active widget. +

+ +
+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: +

+ +

vectors

+ +

+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 vectors. +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 components). +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, red, +green, and blue, which go from 0 to 1. +try putting 0,0.8,1 in a “Buffer” widget and making it active. +now the widget is outputting a 3D vector with x=0, y=0.8, and z=1, so +you’ll get a nice greenish blue color! +

+ +

+.pos is itself a vector, so you can just throw it into the Buffer input: +

+notice how the output is red on the right side of the screen (where the x component of .pos is high) +and green at the top of the screen (where the y component of .pos is high). +

+ +

+most widgets like Multiply work on both numbers and vectors. try multiplying together +.pos and .pos.x: +

+this multiplies each of the components of .pos by .pos.x. +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. +

+ +

multiple widgets

+ +

+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 mul1,0 and 0,0,.pos.x (assuming +your Multiply widget from the last section was called mul1). +

+now the left side looks the same as before, but the right side (where .pos.x is 1) is bluer! +

+ +

putting everything together

+ +

+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 .pos.x, +we'll get a rainbow across the screen: +

+ +
+

+ +

+now let's animate this rainbow: create a new “Add” widget, +and set a=.pos.x, b=.time, +and use that as the shift instead of .pos.x: +

+now the rainbow moves across the screen over time! +

+ +

+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. +

+

+

+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. +

+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. +

+

+now, we don’t have to use .pos as the position for getting +pixel values from the last frame. instead, let’s rotate .pos +by a small amount and use that as the position for the “Last frame” widget: +

+now we’re getting something interesting! +

+ +

+be sure to check out the rest of this guide to learn all the things +you can do with pugl. have fun! 🐱 +

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