@Livelyivy @SteveSwink wow literally resteroni in pepperoni (Today)

@adventureface the conspiracy continues t.co/bhdixPnAiE (2 days ago)

@MattThorson I love how mario just looks really confused (2 days ago)

@LocalNashiora I might have to take my search to the real world which is going to be a pain -_- (2 days ago)

@Livelyivy yeah dang I should have bought 6 pairs when I had the chance (2 days ago)

@gabetelepak I knew I should have bought the entire stock of hot pink pants on ebay two years ago... (2 days ago)

@MoviusC do you want to join my team of investigators (2 days ago)

@aurahack @MllePilgrim @TeddyDief my god i look away for a second and my mentions are blowing up with horrifying imagery (2 days ago)

@gabetelepak yeah I'm after something more like this t.co/zZMauk7Mk3 (2 days ago)

every link I click for "mens pink pants" leads to 404 every image I find leads to a totally different product page how far does this all go (2 days ago)

@legobutts not seeing any on their internets (2 days ago)

@ianlennonford whooaa cool this looks cute as heck :O (2 days ago)

@TeddyDief FAIR guess I need to learn how to make my own clothes now (2 days ago)

@TeddyDief yeah I saw that "video game clothes" store online and it's like "link's tunic: five trillion dollars" (2 days ago)

@TeddyDief why do all clothes SUCK someday we'll have clothes as cool as jrpgs (2 days ago)

@y2bcrazy rainbow is hard to match with other stuff I think (2 days ago)

@Livelyivy haha they're so done. they're going to fade away to nothingness soon unless I do some heavy patching work. (2 days ago)

the internet has everything except for pink pants for guys that aren't a weird salmon color or weak pastel bullshit (2 days ago)

@ChevyRay is there a difference to you between the entire game freezing or action freezing but effect animations still going? (2 days ago)

@ChevyRay Huh interesting this is like my favorite thing ever :o (2 days ago)


2014 - 6 - 11 / 4:06 pm / general

Dev Log: Shader Follow Up

Dev Log: Shader Follow Up

My last post went over some of my recent shader developments with displacement maps, and using gradient maps to recolor portions of the screen. I had a couple of questions of what exactly was going on behind the scenes with the render textures that I was using to tell the shader how to actually manipulate the image, so I thought I would address that now!

Here's an example image from the game with a lot of explosions going on:


Each explosion has a shockwave ripple coming out of it which distorts the area around it. The explosion also changes the color of the screen around to a gradient map with pink and yellow. This makes it look like an intense heat, or something.

For reference, here's the shader again (it's been slightly modified since yesterday.)

uniform sampler2D texture;
uniform sampler2D displacementMap;
uniform sampler2D paletteMap;
uniform sampler2D gradientMap;

void main() {
// Get the pixels off of the maps.
vec4 displacementPixel = texture2D(displacementMap, gl_TexCoord[0]);
vec4 palettePixel = texture2D(paletteMap, gl_TexCoord[0]);

// Read the pixel from the displaced position.
vec2 pos = gl_TexCoord[0];
pos.x += (displacementPixel.r * 2.0 - 1.0) * 0.025;
pos.y -= (displacementPixel.g * 2.0 - 1.0) * 0.025;

// Get the displaced pixel.
vec4 pixel = texture2D(texture, pos);

// Proper grayscale conversion.
float gray = dot(pixel.rgb, vec3(0.299, 0.587, 0.114));

// Get the color from the gradient.
float gradientPos = mod(gray + palettePixel.g, 1);

// Get the actual color from the gradient.
vec4 gradientMapPixel = texture2D(gradientMap, new vec2(gradientPos, palettePixel.r));

// Mix the gradient with the pixel color based on the palette pixel.
pixel = mix(pixel, gradientMapPixel, palettePixel.a);

// Apply the final color multiplied by the gl color.
gl_FragColor = pixel * gl_Color;

From this point on there's going to be a lot of images and some hefty animated gifs, so I'll hide the rest of this post behind the read more button!

Now here's what the displacement map actually looks like:


And here's the image that I'm using to get the shockwave displacement:


The displacement map is filled with gray (127, 127, 127) each frame, and then that shockwave image is rendered to it, much like how each frame for the game window is cleared and then rendered to with many different graphics. After the displacement map has been rendered to, I pass its texture to the shader to use for the displacement.

The gradient mapping is a little simpler. The explosions just render a blue glow to the surface that determines how to remap the colors. Here's how that looks behind the scenes:


And now when it all comes together!


And of course here's a quick look at the shock wave animating:



2014 - 6 - 12 4:57 AM

Abel Toy


I'm amazed at what you can do with shaders, really. That effect is so powerful, and with a really small ammount of code.

I can't wait to experiment with shaders as well, cause that looks fantastic.

Thanks for sharing this insightful post, great job! Can't wait to play with your game :)


2014 - 6 - 22 6:50 AM


This looks really rad makes my tummy go crazy :')


2014 - 6 - 22 12:38 PM


Thanks! :)


2014 - 9 - 10 1:46 PM


That's really amazing.
I wanted to play around with that shader a little bit, so I ported it over to HLSL. I found that the line where you mod the u pos to get the gradientPos was creating artifacts, because it causes the u value to jump to 0 when reaching 1 (which results in jumping from an onscreen white to black on the gradient map). When I removed the line the effect was working a lot better.

Is it cool if I steal the idea with the gradient map for my own projects? :D


2014 - 9 - 11 2:54 PM


Oh weird about the mod issue! Maybe that is a difference with how mod works on HLSL? I don't think I've noticed this on my experiements so far.

Feel free to "steal" the technique! I posted it so that hopefully people would use it on their own stuff ;)


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Hi! My name's Kyle, and I make video games most of the time in Denver, Colorado. 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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