Merge pull request #2 from Chillance/master
shadertoy seascape shader example
This commit is contained in:
Michal Štrba
GitHub
commit
db0af37aa2
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# Shadertoy to Pixel shader conversion
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This will show you an example how you can take an example from [shadertoy.com](shadertoy.com) and use it with the Pixel Shader support.
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["Seascape" by Alexander Alekseev aka TDM - 2014](https://www.shadertoy.com/view/Ms2SD1) is a nice one. It's very impressive and doesn't use textures so that simplifies things for us. Let's try that one.
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Looking at the seascape.glsl example you can see **iResolution**, **iTime** and **iMouse** in there.
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These are commonly needed to be exposed because these things are coming from outside and needs to be updated. Any other variable you need to have changed/updated from code can be exposed like those.
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## Exposing variables
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How to expose variables like this?
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Well, first we need to figure out what type of variables they are. Looking at the shader, you can see **iResolution.x** in there. This tells you that it's not a simple type. In this case it's a **vec2***, a **Vector containing 2 values, x and y**. This makes sense since resolution is described by x and y. That is, width and height.
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And thus, we create our variable in Go with like so:
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```
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uResolution := mgl32.Vec2{float32(win.Bounds().W()), float32(win.Bounds().H())}
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```
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That is, to be of the type **mgl32.Vec2**. Here we create it by taking the window's width and height.
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**iTime** is just a float, and thus that is just created like so:
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```
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var uTime float32
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```
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For the **iMouse**, it's a **mgl32.Vec4**, a **Vector containing 4 variables**. We only use x and y for the mouse position here though.
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```
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var uMouse mgl32.Vec4
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```
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And finally, to make our variables available in the shader itself we use:
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```
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canvas.SetUniform(name string, value interface{})
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```
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We create a handy function to do this:
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``` go
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func EasyBindUniforms(c *pixelgl.Canvas, unifs ...interface{}) {
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if len(unifs)%2 != 0 {
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panic("needs to be divisable by 2")
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}
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for i := 0; i < len(unifs); i += 2 {
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c.SetUniform(unifs[i+0].(string), unifs[i+1])
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}
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}
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```
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and we call that function like so:
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``` go
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EasyBindUniforms(canvas,
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"uResolution", &uResolution,
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"uTime", &uTime,
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"uMouse", &uMouse,
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)
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```
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## Updating shader source file
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We also need to do some updates to the shader file itself to match these variables. First thing would be to add the variables we exposed in Go.
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```
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uniform vec2 uResolution;
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uniform float uTime;
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uniform vec4 uMouse;
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```
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Then we just rename the variables to match.
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We also need to rename the main function itself, as the one used here is specific for use with shadertoy. For our shader, the entrypoint is main(). So we rename:
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```
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void mainImage( out vec4 fragColor, in vec2 fragCoord )
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```
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to
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```
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void main() {
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```
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Also, rename:
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```
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fragCoord
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```
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to
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```
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gl_FragCoord
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```
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because this is available globaly in the OpenGL space for the shader.
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We also need to add:
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```
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out vec4 fragColor;
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```
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to expose that.
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Lastly, we need to add:
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```
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#version 330 core
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```
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at the top to tell what version we require.
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## Using shader
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To use the shader in our canvas we do:
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```
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canvas.SetFragmentShader(fragSource string)
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```
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where fragSource is the fragment shader, not a path fo a file.
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#
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## Result converting shadertoy shader to use with Pixel
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Here is a diff of the changes:
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And that is it. Running the program we should see this:
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package main
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import (
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"io/ioutil"
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"github.com/faiface/pixel"
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"github.com/faiface/pixel/pixelgl"
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)
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// Pixel Shader utility functions
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// EasyBindUniforms does all the work for you, just pass in a
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// valid array adhering to format: String, Variable, ...
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//
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// example:
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//
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// var uTimeVar float32
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// var uMouseVar mgl32.Vec4
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//
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// EasyBindUniforms(win.GetCanvas(),
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// "u_time", &uTimeVar,
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// "u_mouse", &uMouseVar,
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// )
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//
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func EasyBindUniforms(c *pixelgl.Canvas, unifs ...interface{}) {
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if len(unifs)%2 != 0 {
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panic("needs to be divisable by 2")
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}
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for i := 0; i < len(unifs); i += 2 {
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c.SetUniform(unifs[i+0].(string), unifs[i+1])
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}
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}
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// CenterWindow will... center the window
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func CenterWindow(win *pixelgl.Window) {
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x, y := pixelgl.PrimaryMonitor().Size()
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width, height := win.Bounds().Size().XY()
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win.SetPos(
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pixel.V(
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x/2-width/2,
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y/2-height/2,
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),
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)
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}
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// LoadFileToString loads the contents of a file into a string
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func LoadFileToString(filename string) (string, error) {
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b, err := ioutil.ReadFile(filename)
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if err != nil {
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return "", err
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}
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return string(b), nil
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}
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Binary file not shown.
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After Width: | Height: | Size: 3.7 MiB |
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package main
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import (
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"time"
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"github.com/go-gl/mathgl/mgl32"
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"github.com/faiface/pixel"
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"github.com/faiface/pixel/pixelgl"
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"golang.org/x/image/colornames"
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)
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func run() {
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// Set up window configs
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cfg := pixelgl.WindowConfig{ // Default: 1024 x 768
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Title: "Golang Seascape from Shadertoy",
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Bounds: pixel.R(0, 0, 1024, 768),
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VSync: true,
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}
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win, err := pixelgl.NewWindow(cfg)
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if err != nil {
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panic(err)
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}
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camVector := win.Bounds().Center()
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bounds := win.Bounds()
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bounds.Max = bounds.Max.ScaledXY(pixel.V(1.0, 1.0))
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// I am putting all shader example initializing stuff here for
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// easier reference to those learning to use this functionality
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fragSource, err := LoadFileToString("shaders/seascape.glsl")
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if err != nil {
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panic(err)
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}
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var uMouse mgl32.Vec4
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var uTime float32
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canvas := win.Canvas()
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uResolution := mgl32.Vec2{float32(win.Bounds().W()), float32(win.Bounds().H())}
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EasyBindUniforms(canvas,
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"uResolution", &uResolution,
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"uTime", &uTime,
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"uMouse", &uMouse,
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)
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canvas.SetFragmentShader(fragSource)
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start := time.Now()
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// Game Loop
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for !win.Closed() {
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uTime = float32(time.Since(start).Seconds())
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mpos := win.MousePosition()
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uMouse[0] = float32(mpos.X)
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uMouse[1] = float32(mpos.Y)
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win.Clear(colornames.Black)
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// Drawing to the screen
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canvas.Draw(win, pixel.IM.Moved(camVector))
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win.Update()
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}
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}
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func main() {
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pixelgl.Run(run)
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}
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Binary file not shown.
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After Width: | Height: | Size: 381 KiB |
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/*
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* "Seascape" by Alexander Alekseev aka TDM - 2014
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* License Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
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* Contact: tdmaav@gmail.com
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*/
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#version 330 core
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uniform vec2 uResolution;
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uniform float uTime;
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uniform vec4 uMouse;
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out vec4 fragColor;
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const int NUM_STEPS = 8;
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const float PI = 3.141592;
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const float EPSILON = 1e-3;
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#define EPSILON_NRM (0.1 / uResolution.x)
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// sea
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const int ITER_GEOMETRY = 3;
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const int ITER_FRAGMENT = 5;
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const float SEA_HEIGHT = 0.6;
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const float SEA_CHOPPY = 4.0;
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const float SEA_SPEED = 0.8;
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const float SEA_FREQ = 0.16;
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const vec3 SEA_BASE = vec3(0.1,0.19,0.22);
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const vec3 SEA_WATER_COLOR = vec3(0.8,0.9,0.6);
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#define SEA_TIME (1.0 + uTime * SEA_SPEED)
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const mat2 octave_m = mat2(1.6,1.2,-1.2,1.6);
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// math
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mat3 fromEuler(vec3 ang) {
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vec2 a1 = vec2(sin(ang.x),cos(ang.x));
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vec2 a2 = vec2(sin(ang.y),cos(ang.y));
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vec2 a3 = vec2(sin(ang.z),cos(ang.z));
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mat3 m;
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m[0] = vec3(a1.y*a3.y+a1.x*a2.x*a3.x,a1.y*a2.x*a3.x+a3.y*a1.x,-a2.y*a3.x);
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m[1] = vec3(-a2.y*a1.x,a1.y*a2.y,a2.x);
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m[2] = vec3(a3.y*a1.x*a2.x+a1.y*a3.x,a1.x*a3.x-a1.y*a3.y*a2.x,a2.y*a3.y);
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return m;
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}
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float hash( vec2 p ) {
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float h = dot(p,vec2(127.1,311.7));
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return fract(sin(h)*43758.5453123);
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}
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float noise( in vec2 p ) {
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vec2 i = floor( p );
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vec2 f = fract( p );
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vec2 u = f*f*(3.0-2.0*f);
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return -1.0+2.0*mix( mix( hash( i + vec2(0.0,0.0) ),
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hash( i + vec2(1.0,0.0) ), u.x),
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mix( hash( i + vec2(0.0,1.0) ),
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hash( i + vec2(1.0,1.0) ), u.x), u.y);
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}
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// lighting
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float diffuse(vec3 n,vec3 l,float p) {
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return pow(dot(n,l) * 0.4 + 0.6,p);
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}
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float specular(vec3 n,vec3 l,vec3 e,float s) {
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float nrm = (s + 8.0) / (PI * 8.0);
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return pow(max(dot(reflect(e,n),l),0.0),s) * nrm;
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}
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// sky
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vec3 getSkyColor(vec3 e) {
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e.y = max(e.y,0.0);
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return vec3(pow(1.0-e.y,2.0), 1.0-e.y, 0.6+(1.0-e.y)*0.4);
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}
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// sea
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float sea_octave(vec2 uv, float choppy) {
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uv += noise(uv);
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vec2 wv = 1.0-abs(sin(uv));
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vec2 swv = abs(cos(uv));
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wv = mix(wv,swv,wv);
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return pow(1.0-pow(wv.x * wv.y,0.65),choppy);
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}
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float map(vec3 p) {
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float freq = SEA_FREQ;
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float amp = SEA_HEIGHT;
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float choppy = SEA_CHOPPY;
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vec2 uv = p.xz; uv.x *= 0.75;
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float d, h = 0.0;
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for(int i = 0; i < ITER_GEOMETRY; i++) {
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d = sea_octave((uv+SEA_TIME)*freq,choppy);
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d += sea_octave((uv-SEA_TIME)*freq,choppy);
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h += d * amp;
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uv *= octave_m; freq *= 1.9; amp *= 0.22;
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choppy = mix(choppy,1.0,0.2);
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}
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return p.y - h;
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}
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float map_detailed(vec3 p) {
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float freq = SEA_FREQ;
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float amp = SEA_HEIGHT;
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float choppy = SEA_CHOPPY;
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vec2 uv = p.xz; uv.x *= 0.75;
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float d, h = 0.0;
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for(int i = 0; i < ITER_FRAGMENT; i++) {
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d = sea_octave((uv+SEA_TIME)*freq,choppy);
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d += sea_octave((uv-SEA_TIME)*freq,choppy);
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h += d * amp;
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uv *= octave_m; freq *= 1.9; amp *= 0.22;
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choppy = mix(choppy,1.0,0.2);
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}
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return p.y - h;
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}
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vec3 getSeaColor(vec3 p, vec3 n, vec3 l, vec3 eye, vec3 dist) {
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float fresnel = clamp(1.0 - dot(n,-eye), 0.0, 1.0);
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fresnel = pow(fresnel,3.0) * 0.65;
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vec3 reflected = getSkyColor(reflect(eye,n));
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vec3 refracted = SEA_BASE + diffuse(n,l,80.0) * SEA_WATER_COLOR * 0.12;
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vec3 color = mix(refracted,reflected,fresnel);
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float atten = max(1.0 - dot(dist,dist) * 0.001, 0.0);
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color += SEA_WATER_COLOR * (p.y - SEA_HEIGHT) * 0.18 * atten;
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color += vec3(specular(n,l,eye,60.0));
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return color;
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}
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// tracing
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vec3 getNormal(vec3 p, float eps) {
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vec3 n;
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n.y = map_detailed(p);
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n.x = map_detailed(vec3(p.x+eps,p.y,p.z)) - n.y;
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n.z = map_detailed(vec3(p.x,p.y,p.z+eps)) - n.y;
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n.y = eps;
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return normalize(n);
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}
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float heightMapTracing(vec3 ori, vec3 dir, out vec3 p) {
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float tm = 0.0;
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float tx = 1000.0;
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float hx = map(ori + dir * tx);
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if(hx > 0.0) return tx;
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float hm = map(ori + dir * tm);
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float tmid = 0.0;
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for(int i = 0; i < NUM_STEPS; i++) {
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tmid = mix(tm,tx, hm/(hm-hx));
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p = ori + dir * tmid;
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float hmid = map(p);
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if(hmid < 0.0) {
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tx = tmid;
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hx = hmid;
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} else {
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tm = tmid;
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hm = hmid;
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}
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}
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return tmid;
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}
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// main
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void main()
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{
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vec2 uv = gl_FragCoord.xy / uResolution.xy;
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uv = uv * 2.0 - 1.0;
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uv.x *= uResolution.x / uResolution.y;
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float time = uTime * 0.3 + uMouse.x*0.01;
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// ray
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vec3 ang = vec3(sin(time*3.0)*0.1,sin(time)*0.2+0.3,time);
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vec3 ori = vec3(0.0,3.5,time*5.0);
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vec3 dir = normalize(vec3(uv.xy,-2.0)); dir.z += length(uv) * 0.15;
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dir = normalize(dir) * fromEuler(ang);
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// tracing
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vec3 p;
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heightMapTracing(ori,dir,p);
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vec3 dist = p - ori;
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vec3 n = getNormal(p, dot(dist,dist) * EPSILON_NRM);
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vec3 light = normalize(vec3(0.0,1.0,0.8));
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// color
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vec3 color = mix(
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getSkyColor(dir),
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getSeaColor(p,n,light,dir,dist),
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pow(smoothstep(0.0,-0.05,dir.y),0.3));
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// post
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fragColor = vec4(pow(color,vec3(0.75)), 1.0);
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}
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@ -0,0 +1,184 @@
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/*
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* "Seascape" by Alexander Alekseev aka TDM - 2014
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* License Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
|
||||
* Contact: tdmaav@gmail.com
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*/
|
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const int NUM_STEPS = 8;
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const float PI = 3.141592;
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const float EPSILON = 1e-3;
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#define EPSILON_NRM (0.1 / iResolution.x)
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// sea
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const int ITER_GEOMETRY = 3;
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const int ITER_FRAGMENT = 5;
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const float SEA_HEIGHT = 0.6;
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const float SEA_CHOPPY = 4.0;
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const float SEA_SPEED = 0.8;
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const float SEA_FREQ = 0.16;
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const vec3 SEA_BASE = vec3(0.1,0.19,0.22);
|
||||
const vec3 SEA_WATER_COLOR = vec3(0.8,0.9,0.6);
|
||||
#define SEA_TIME (1.0 + iTime * SEA_SPEED)
|
||||
const mat2 octave_m = mat2(1.6,1.2,-1.2,1.6);
|
||||
|
||||
// math
|
||||
mat3 fromEuler(vec3 ang) {
|
||||
vec2 a1 = vec2(sin(ang.x),cos(ang.x));
|
||||
vec2 a2 = vec2(sin(ang.y),cos(ang.y));
|
||||
vec2 a3 = vec2(sin(ang.z),cos(ang.z));
|
||||
mat3 m;
|
||||
m[0] = vec3(a1.y*a3.y+a1.x*a2.x*a3.x,a1.y*a2.x*a3.x+a3.y*a1.x,-a2.y*a3.x);
|
||||
m[1] = vec3(-a2.y*a1.x,a1.y*a2.y,a2.x);
|
||||
m[2] = vec3(a3.y*a1.x*a2.x+a1.y*a3.x,a1.x*a3.x-a1.y*a3.y*a2.x,a2.y*a3.y);
|
||||
return m;
|
||||
}
|
||||
float hash( vec2 p ) {
|
||||
float h = dot(p,vec2(127.1,311.7));
|
||||
return fract(sin(h)*43758.5453123);
|
||||
}
|
||||
float noise( in vec2 p ) {
|
||||
vec2 i = floor( p );
|
||||
vec2 f = fract( p );
|
||||
vec2 u = f*f*(3.0-2.0*f);
|
||||
return -1.0+2.0*mix( mix( hash( i + vec2(0.0,0.0) ),
|
||||
hash( i + vec2(1.0,0.0) ), u.x),
|
||||
mix( hash( i + vec2(0.0,1.0) ),
|
||||
hash( i + vec2(1.0,1.0) ), u.x), u.y);
|
||||
}
|
||||
|
||||
// lighting
|
||||
float diffuse(vec3 n,vec3 l,float p) {
|
||||
return pow(dot(n,l) * 0.4 + 0.6,p);
|
||||
}
|
||||
float specular(vec3 n,vec3 l,vec3 e,float s) {
|
||||
float nrm = (s + 8.0) / (PI * 8.0);
|
||||
return pow(max(dot(reflect(e,n),l),0.0),s) * nrm;
|
||||
}
|
||||
|
||||
// sky
|
||||
vec3 getSkyColor(vec3 e) {
|
||||
e.y = max(e.y,0.0);
|
||||
return vec3(pow(1.0-e.y,2.0), 1.0-e.y, 0.6+(1.0-e.y)*0.4);
|
||||
}
|
||||
|
||||
// sea
|
||||
float sea_octave(vec2 uv, float choppy) {
|
||||
uv += noise(uv);
|
||||
vec2 wv = 1.0-abs(sin(uv));
|
||||
vec2 swv = abs(cos(uv));
|
||||
wv = mix(wv,swv,wv);
|
||||
return pow(1.0-pow(wv.x * wv.y,0.65),choppy);
|
||||
}
|
||||
|
||||
float map(vec3 p) {
|
||||
float freq = SEA_FREQ;
|
||||
float amp = SEA_HEIGHT;
|
||||
float choppy = SEA_CHOPPY;
|
||||
vec2 uv = p.xz; uv.x *= 0.75;
|
||||
|
||||
float d, h = 0.0;
|
||||
for(int i = 0; i < ITER_GEOMETRY; i++) {
|
||||
d = sea_octave((uv+SEA_TIME)*freq,choppy);
|
||||
d += sea_octave((uv-SEA_TIME)*freq,choppy);
|
||||
h += d * amp;
|
||||
uv *= octave_m; freq *= 1.9; amp *= 0.22;
|
||||
choppy = mix(choppy,1.0,0.2);
|
||||
}
|
||||
return p.y - h;
|
||||
}
|
||||
|
||||
float map_detailed(vec3 p) {
|
||||
float freq = SEA_FREQ;
|
||||
float amp = SEA_HEIGHT;
|
||||
float choppy = SEA_CHOPPY;
|
||||
vec2 uv = p.xz; uv.x *= 0.75;
|
||||
|
||||
float d, h = 0.0;
|
||||
for(int i = 0; i < ITER_FRAGMENT; i++) {
|
||||
d = sea_octave((uv+SEA_TIME)*freq,choppy);
|
||||
d += sea_octave((uv-SEA_TIME)*freq,choppy);
|
||||
h += d * amp;
|
||||
uv *= octave_m; freq *= 1.9; amp *= 0.22;
|
||||
choppy = mix(choppy,1.0,0.2);
|
||||
}
|
||||
return p.y - h;
|
||||
}
|
||||
|
||||
vec3 getSeaColor(vec3 p, vec3 n, vec3 l, vec3 eye, vec3 dist) {
|
||||
float fresnel = clamp(1.0 - dot(n,-eye), 0.0, 1.0);
|
||||
fresnel = pow(fresnel,3.0) * 0.65;
|
||||
|
||||
vec3 reflected = getSkyColor(reflect(eye,n));
|
||||
vec3 refracted = SEA_BASE + diffuse(n,l,80.0) * SEA_WATER_COLOR * 0.12;
|
||||
|
||||
vec3 color = mix(refracted,reflected,fresnel);
|
||||
|
||||
float atten = max(1.0 - dot(dist,dist) * 0.001, 0.0);
|
||||
color += SEA_WATER_COLOR * (p.y - SEA_HEIGHT) * 0.18 * atten;
|
||||
|
||||
color += vec3(specular(n,l,eye,60.0));
|
||||
|
||||
return color;
|
||||
}
|
||||
|
||||
// tracing
|
||||
vec3 getNormal(vec3 p, float eps) {
|
||||
vec3 n;
|
||||
n.y = map_detailed(p);
|
||||
n.x = map_detailed(vec3(p.x+eps,p.y,p.z)) - n.y;
|
||||
n.z = map_detailed(vec3(p.x,p.y,p.z+eps)) - n.y;
|
||||
n.y = eps;
|
||||
return normalize(n);
|
||||
}
|
||||
|
||||
float heightMapTracing(vec3 ori, vec3 dir, out vec3 p) {
|
||||
float tm = 0.0;
|
||||
float tx = 1000.0;
|
||||
float hx = map(ori + dir * tx);
|
||||
if(hx > 0.0) return tx;
|
||||
float hm = map(ori + dir * tm);
|
||||
float tmid = 0.0;
|
||||
for(int i = 0; i < NUM_STEPS; i++) {
|
||||
tmid = mix(tm,tx, hm/(hm-hx));
|
||||
p = ori + dir * tmid;
|
||||
float hmid = map(p);
|
||||
if(hmid < 0.0) {
|
||||
tx = tmid;
|
||||
hx = hmid;
|
||||
} else {
|
||||
tm = tmid;
|
||||
hm = hmid;
|
||||
}
|
||||
}
|
||||
return tmid;
|
||||
}
|
||||
|
||||
// main
|
||||
void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
|
||||
vec2 uv = fragCoord.xy / iResolution.xy;
|
||||
uv = uv * 2.0 - 1.0;
|
||||
uv.x *= iResolution.x / iResolution.y;
|
||||
float time = iTime * 0.3 + iMouse.x*0.01;
|
||||
|
||||
// ray
|
||||
vec3 ang = vec3(sin(time*3.0)*0.1,sin(time)*0.2+0.3,time);
|
||||
vec3 ori = vec3(0.0,3.5,time*5.0);
|
||||
vec3 dir = normalize(vec3(uv.xy,-2.0)); dir.z += length(uv) * 0.15;
|
||||
dir = normalize(dir) * fromEuler(ang);
|
||||
|
||||
// tracing
|
||||
vec3 p;
|
||||
heightMapTracing(ori,dir,p);
|
||||
vec3 dist = p - ori;
|
||||
vec3 n = getNormal(p, dot(dist,dist) * EPSILON_NRM);
|
||||
vec3 light = normalize(vec3(0.0,1.0,0.8));
|
||||
|
||||
// color
|
||||
vec3 color = mix(
|
||||
getSkyColor(dir),
|
||||
getSeaColor(p,n,light,dir,dist),
|
||||
pow(smoothstep(0.0,-0.05,dir.y),0.3));
|
||||
|
||||
// post
|
||||
fragColor = vec4(pow(color,vec3(0.75)), 1.0);
|
||||
}
|
||||
Loading…
Reference in New Issue