RT @saint11: I made the smallest pixel font I could think of, and it's free. Like, public domain free t.co/2hs4ygCXej t.co/wL… (Today)

RT @LunarRayGames: Hurray! Timespinner now has a Coming Soon™ page on Steam :D t.co/eUxZEJ8JYO t.co/GqDmaCfypV (Today)

@ChevyRay @MllePilgrim @djcoreynolan @MattThorson leaving on sep 9th. Getting into the train station at 2pm today ;D (Today)

@MllePilgrim @djcoreynolan @MattThorson yaaaaaa (Yesterday)

RT @Crumps2: His hair was the giveaway @kylepulver is awesome t.co/W6AMT5CTrd (Yesterday)

RT @IvanDashSmith: I met the awesome @kylepulver, and it turns out the blue in his twitter avatar is his hair and not a hoodie! (2 days ago)

@konjak wow real mature (2 days ago)

@LinxordZX are you on the beta branch on steam? Instructions are on the steam forums. (3 days ago)

There's a disturbingly high amount of cool games at PAX not giving out buttons... :I (3 days ago)

@ADAMATOMIC @infinite_ammo I swear it said display eat poop at first. (4 days ago)

@Arc0re_1 I saw a video of it running on Linux once. I personally have no idea how to do it though. (4 days ago)

I just walked around the not even built expo halls and already feel exhausted. Best of luck exhibitors don't forget your cough drops. #pax (5 days ago)

Overcame the terror of flying once again. In Seattle now. Let's do this. (5 days ago)

@mwegner At first I thought you were sad at the end of your tweet. (8 days ago)

@Lumin0via storyboard a short! ;D (9 days ago)

@paste0x78 Thanks! (10 days ago)

@MattThorson it's just like towerfall but in 3d (10 days ago)

Slowly getting better at aerials in car soccer t.co/81qlq6y4iH :D (10 days ago)

@floatvoid @ChevyRay ugh jeremy you must be sitting on a fuckin treasure trove of otter improvements SUBMIT PULL REQUESTS ALREADY (10 days ago)

@EvanEGibbs I'm working on a lot of stuff but I keep bringing things to 95% done and shying away from them haha (12 days ago)


2014 - 6 - 2 / 4:09 pm / general

Dev Log: Shader Experiments

Dev Log: Shader Experiments

Since my break to work on the remaining bits of Otter I haven't really fallen back into the groove on working on my big game project yet. Yesterday I dedicated the day to playing around with shaders since I'm really interested in using them for all kinds of cool visual effects.


This is what I ended up coming up with at the end of the day. First I was playing around with gradient maps for recoloring an image, and then I started to mess with displacement to make cool waves in the image. Finally I wanted to experiment with having a render texture that could be passed to the shader for dynamic effects.

Basically how this little program works is that there is the static image with a shader loaded. Then there's a Surface object that can be painted on with the mouse. The shader uses the texture from that Surface to affect the image in different ways.

Here's the full C# source:

using Otter;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ShaderTesting {
class Program {
static void Main(string[] args) {
var image = new Image("pic.jpg");
var game = new Game("ShaderZ", image.Width, image.Height);

game.FirstScene = new TestScene();


class TestScene : Scene {

Image image = new Image("pic.jpg");
Image circle = new Image("circle.png");
Surface distortion;

public TestScene() {
distortion = new Surface(image.Width, image.Height);
circle.Blend = BlendMode.Add;
circle.Alpha = 0.1f;
distortion.Visible = false;
distortion.AutoClear = false;

public override void Update() {

if (Timer % 30 == 0) {
try {
image.Shader = new Shader("../../shader.frag");
catch(Exception e) {
Console.WriteLine("Shader error:");
image.Shader.SetParameter("gradient", new Texture("gradient.png"));
if (Input.MouseButtonPressed(MouseButton.Right)) {
image.Shader.SetParameter("time", Timer);
image.Shader.SetParameter("distortion", distortion.Texture);
image.Shader.SetParameter("offset", Util.SinScale(Timer, 0, 1));

if (Input.MouseButtonDown(MouseButton.Left)) {
Draw.Graphic(circle, MouseX, image.Height - MouseY);

public override void Render() {

Draw.Circle(MouseX - 15, MouseY - 15, 30, Color.None, Color.Red, 2);

And the GLSL shader source:

sampler2D texture;
sampler2D gradient;
sampler2D distortion;
uniform float offset;
uniform float time;
uniform float mixfactor;

void main() {
vec2 pos = gl_TexCoord[0];
vec2 distortColor = texture2D(distortion, pos);
pos.x += distortColor.r * (sin(time * 0.1 + pos.x * 10) * 0.05);
pos.y -= distortColor.g * (cos(time * 0.1 + pos.y * 10) * 0.05);
vec4 color = texture2D(texture, pos);

float gray = (color.r + color.g + color.b) / 3;

vec4 gradientColor = texture2D(gradient, vec2(gray, offset));

gl_FragColor = mix(color, gradientColor, distortColor.r + distortColor.g);

You can download everything here. Note that you'll have to give it a reference to Otter to compile and run it yourself.


2014 - 6 - 10 9:57 PM

R Brack

Are you meant to be creating a new shader and texture every 30 (seconds? milliseconds?) That seems a bit rough to me.


2014 - 6 - 11 1:25 AM


It's actually every half second (60 fps.) It's so I can edit the shader, save, and see my changes almost instantly instead of having to rebuild the application. I don't notice any performance issues.


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Hi there, my name is Kyle, and I'm a kid disguised as a grown up. I'm making video games and living the indie game developer life in Tempe, Arizona. Here you will find my thoughts, games, websites, doodles, and other stuff like that. I worked on Snapshot, Offspring Fling, and a whole bunch of other games. I also created and maintain Otter, a 2d game making framework. If you want to get a hold of me use the form on the bottom of the page, leave a comment, or just tweet at me. I try to post three times a week. Thanks for stoppin' by! You're the coolest.

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