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@@ -1,133 +1,5 @@ -# Shadertoy to Pixel shader conversion +# nogui -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. +Package gui implements a abstraction layer for Go visual elements. -["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. - -Looking at the seascape.glsl example you can see **iResolution**, **iTime** and **iMouse** in there. - -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. - -## Command line arguments - -``` -./seascape-shader -h # will show you the command line options - -./seascape-shader -filename ./shaders/seascape.glsl # Seascape -./seascape-shader -filename ./shaders/planetfall.glsl # Planet Fall demo -``` - -## Exposing variables - -How to expose variables like this? - -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. - -And thus, we create our variable in Go with like so: -``` -uResolution := mgl32.Vec2{float32(win.Bounds().W()), float32(win.Bounds().H())} -``` -That is, to be of the type **mgl32.Vec2**. Here we create it by taking the window's width and height. - -**iTime** is just a float, and thus that is just created like so: -``` -var uTime float32 -``` - -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. -``` -var uMouse mgl32.Vec4 -``` - -And finally, to make our variables available in the shader itself we use: -``` -canvas.SetUniform(name string, value interface{}) -``` - -We create a handy function to do this: - -``` go -func EasyBindUniforms(c *pixelgl.Canvas, unifs ...interface{}) { - if len(unifs)%2 != 0 { - panic("needs to be divisable by 2") - } - for i := 0; i < len(unifs); i += 2 { - - c.SetUniform(unifs[i+0].(string), unifs[i+1]) - } -} -``` -and we call that function like so: - -``` go - EasyBindUniforms(canvas, - "uResolution", &uResolution, - "uTime", &uTime, - "uMouse", &uMouse, - ) -``` - -## Updating shader source file - -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. - -``` -uniform vec2 uResolution; -uniform float uTime; -uniform vec4 uMouse; -``` -Then we just rename the variables to match. - -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: -``` -void mainImage( out vec4 fragColor, in vec2 fragCoord ) -``` -to -``` -void main() { -``` - - -Also, rename: -``` -fragCoord -``` -to -``` -gl_FragCoord -``` -because this is available globaly in the OpenGL space for the shader. - -We also need to add: -``` -out vec4 fragColor; -``` - -to expose that. - -Lastly, we need to add: -``` -#version 330 core -``` -at the top to tell what version we require. - - -## Using shader -To use the shader in our canvas we do: -``` -canvas.SetFragmentShader(fragSource string) -``` -where fragSource is the fragment shader, not a path fo a file. - -# - -## Result converting shadertoy shader to use with Pixel - -Here is a diff of the changes: - - - - -And that is it. Running the program we should see this: - - +This is a sample plugin. It's a skeleton intended to be used when making a new toolkit plugin. |