Porting a Shader to SFML - c++

Question

I don't have much experience with Shader or GLSL. I am trying to practice with them. To this end I'm trying to port this shader.
https://www.shadertoy.com/view/XsXGR7
Into a project to use with SFML. I am having issue doing this and I'm not sure what to do to start fixing the issues.
I messed around with the uniforms and a few varaiable but the shader itself keeps giving the same error message. That it won't compile. Not sure why, I assume it's because without converting it to work with SFML it's asking for input from OpenGL.
Shader file
uniform vec3 iResolution; // viewport resolution (in pixels)
uniform float iTime; // shader playback time (in seconds)
uniform float iTimeDelta; // render time (in seconds)
uniform int iFrame; // shader playback frame
uniform float iChannelTime[4]; // channel playback time (in seconds)
uniform vec3 iChannelResolution[4]; // channel resolution (in pixels)
uniform vec4 iMouse; // mouse pixel coords. xy: current (if MLB down), zw: click
uniform samplerXX iChannel0..3; // input channel. XX = 2D/Cube
uniform vec4 iDate; // (year, month, day, time in seconds)
uniform float iSampleRate; // sound sample rate (i.e., 44100)
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
vec3 waveParams = vec3( 10.0, 0.8, 0.1 );
vec2 tmp = vec2( iMouse.xy / iResolution.xy );
vec2 uv = fragCoord.xy / iResolution.xy;
vec2 texCoord = uv;
float distance = distance(uv, tmp);
if ( (distance <= ((iTime ) + waveParams.z )) && ( distance >= ((iTime ) - waveParams.z)) )
{
float diff = (distance - (iTime));
float powDiff = 1.0 - pow(abs(diff*waveParams.x), waveParams.y);
float diffTime = diff * powDiff;
vec2 diffUV = normalize(uv - tmp);
texCoord = uv + (diffUV * diffTime);
}
vec4 original = texture( iChannel0, texCoord);
fragColor = original;
}
Currently all the shader does is get loaded in.
shader.loadFromFile("ASSETS/SHADERS/Shockwave1.txt",sf::Shader::Fragment);
//load the shader
if (!shader.isAvailable()) {
std::cout << "The shader is not available\n";
}
Error message trying to load the above shader. No uniforms set, nothing is done with the shader aside from loading it.
Failed to compile fragment shader:
WARNING: 0:1 '' : #version directive missing
ERROR: 0:8 'iChannel0 : syntax error syntax error
Edit:
Having replaced "samplerXX" with "sampler2D" and inserted a void main() function the shader loads properly. Getting the code to work is now the issue.
The Main()
void main(out vec4 fragColor, in vec2 fragCoord )
{
vec3 waveParams = vec3( 10.0, 0.8, 0.1 );
vec2 tmp = vec2( iMouse.xy / iResolution.xy );
vec2 uv = fragCoord.xy / iResolution.xy;
vec2 texCoord = uv;
float distance = distance(uv, tmp);
if ( (distance <= ((iTime ) + waveParams.z )) && ( distance >= ((iTime ) - waveParams.z)) )
{
float diff = (distance - (iTime));
float powDiff = 1.0 - pow(abs(diff*waveParams.x), waveParams.y);
float diffTime = diff * powDiff;
vec2 diffUV = normalize(uv - tmp);
texCoord = uv + (diffUV * diffTime);
}
vec4 original = texture( iChannel0, texCoord);
fragColor = original;
}
This produces these errors
Failed to compile fragment shader:
WARNING: 0:1: '' : #version directive missing
WARNING: 0:32: 'function' : is not available in current GLSL version texture
ERROR: 0:34: 'main' : function cannot take any parameter(s)
WARNING: 0:53: 'function' : is not available in current GLSL version texture
While the main not taking parameters is straightforward I would like to know would values be passed in strictly using uniforms? I am not sure what the 'function' errors relate to.
Edit:
Main()
void main( )
{
vec2 fragCoord = vec2(20,20);
vec3 waveParams = vec3( 10.0, 0.8, 0.1 );
vec2 tmp = vec2( iMouse.xy / iResolution.xy );
vec2 uv = fragCoord.xy / iResolution.xy;
vec2 texCoord = uv;
float distance = distance(uv, tmp);
if ( (distance <= ((iTime ) + waveParams.z )) && ( distance >= ((iTime ) - waveParams.z)) )
{
float diff = (distance - (iTime));
float powDiff = 1.0 - pow(abs(diff*waveParams.x), waveParams.y);
float diffTime = diff * powDiff;
vec2 diffUV = normalize(uv - tmp);
texCoord = uv + (diffUV * diffTime);
}
vec4 original = texture( iChannel0, texCoord);
gl_FragColor = original;
}
Removing the main parameters, hardcode defining vec2 fragCoord as vec2(20,20) made the shader run without issue. My question now is this enough to output the shader effect? (Little experience with glsl, sorry if this is a dumb question)
gl_FragColor = original;
And if it is this seems to be the position of the pixel to be shaded. Is there a way to pass this in automatically?
vec2 fragCoord