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/index.html | 122 +++++---------------------------------------------- 1 file changed, 12 insertions(+), 110 deletions(-) (limited to 'guide-src/index.html') 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 -

your first pugl

+

pugl

+pommicket's utility for gl shaders +

-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. + pugl is a tool that lets you create & share shaders without writing any code.

-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 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. -

+ to learn how to use pugl, check out the next section.

+

credits

+

-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. +icon based on +Long-beakedEchidna.jpg from WikiMedia +CC BY-SA 3.0.

-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! 🐱 -

+everything else is licensed under WTFPLv2. -- cgit v1.2.3