Shader Toy to C2

Hi L&G

I will try to write a tutorial for converting Shadertoy Glsl to C2 FX;

'i will try'===> is the quantum theory that's mean the final result (maybe) will fail depend

of what i will write or how you will understand this.

Ok let's start ; firts we will take the .xml file on C2 basic FX;

--- .xml file is atached to this tutorial;

the xml file and fx file must called like this.

myfx.xml

myfx.fx

And now take .fx file from Shader Toy basic fx;

---- what is this ???? so explain this quickly

We are void mainImage( out--> in)

1 . We must enter with fragment coordinate and out with Fragment color.

Let's translate it to C2 glsl avaiable commands... go to ROJOhound explanation;

scirra.com/forum/documentation-on-built-in-uniforms_t115900

**varying vec2 vTex

This is the vertex co-ordinate of the current pixel

uniform sampler2D samplerFront

this is the source pixels. AKA the object's texture or the result of the previous shader.

uniform sampler2D samplerBack

this is where stuff is being drawn to

uniform float pixelWidth

1.0/width or in other words a pixel width in vertex co-ordinates

uniform float pixelHeight

1.0/height or in other words a pixel height in vertex co-ordinates

uniform vec2 destStart

The top-left vertex co-ordinate of the rectange being drawn to.

uniform vec2 destEnd

The bottom-right vertex co-ordinate of the rectange being drawn to.

For example a rectangle that covers the entire screen would have a destStart of (0,0) and a destEnd of (1,1)

Usually they define a rectangle that covers just the object, but depending on the xml settings it can be larger.

uniform float layerScale

uniform float layerAngle

^ In radians I think.

Both these are basically the same as their counterparts in C2

Now the folling two aren't used in any bundled effects but they'd have the same values as ViewportLeft(0), ViewportTop(0) and scrollx and scroly respectively.

uniform vec2 viewOrigin

Top-left of screen in layout pixels

uniform vec2 scrollPos

Center of screen in layout pixels.

uniform float seconds

Time.

uniform float opacity

Current object/layer opacity in the range of 0.0 to 1.0**

Extract our commands .... and make C2 usable commands we need for all fx we make for future ;

#ifdef GL_ES

precision mediump float;

#endif

uniform mediump sampler2D samplerFront;

varying mediump vec2 vTex;

uniform mediump float seconds;

uniform mediump float pixelWidth;

uniform mediump float pixelHeight;

vec2 iResolution = vec2( 1./pixelWidth, 1./pixelHeight);

Get the shadertoy example again ;

Let's convert it to C2;

ST : void mainImage( out vec4 fragColor, in vec2 fragCoord )

C2: void main()

ST: vec2 uv = fragCoord.xy / iResolution.xy;

C2:vec2 uv = vTex; <== this is declared above

ST:fragColor = vec4(uv,0.5+0.5*sin(iGlobalTime),1.0);

C2:gl_FragColor = vec4(uv,0.5+0.5*sin(seconds),1.0);

Finaly we have our glsl for C2;

void main()

{

vec2 uv =vText;

gl_FragColor = vec4(uv,0.5+0.5*sin(seconds),1.0);

}

explanation

if we look st first line ; void mainImage( out vec4 fragColor, in vec2 fragCoord )

fragcolor have 4 variables ; like a,b,c,d and fragcoord have 2 variables like a,b

In c2 uv=vec2; vec2 mean 2 variables;

gl_FragColor have 4 var...