shadertoy to SFML

Question

I'm trying to port a shadertoy shader to an SFML application.

The problem I have is with this line:

float g = texture(iChannel0, uv+vec2(nh-0.07, 0.0)*nh).g;

I Think that iChannel0 is a 2D sampler and is the video running in the browser.

I need to substitute the iChannel0 with something else but not sure how since I'm totally new to GLSL.

I have a vertex shader that looks like this:

void main()
{
    // Transforming The Vertex
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;

    // transform the texture coordinates
    gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;

    // forward the vertex color
    gl_FrontColor = gl_Color;
}

and in my fragment shader I have the rest of the modified code including the above line containing the iChannel0 parameter.

The shader is applied as a post effect to the whole screen.

I was able to convert everything else with the exception of that last line.

Thanks for your help.

Answer 1

OK, I got it to work like this:

At the top of my fragment shader file, I added:

uniform sampler2D sourceTexture;

I changed:

float g = texture(iChannel0, uv+vec2(nh-0.07, 0.0)*nh).g;

to:

 float g = texture2D(sourceTexture, uv+vec2(nh-0.07, 0.0)*nh).g;

and in my SFML code:

shader->setParameter("sourceTexture", sf::Shader::CurrentTexture);