Input texture into GL3 - Shader Toy Loader

Ok massively close, but not a direct replica or drop in replacement for the sound iChannel0 just yet.

Here's the results from my progress so far:

https://youtu.be/rriN2uJQ3ao

and here's the patch:

I may have to call it a night now and stop working on it. It's functional, but the mapping is not perfect. (upside down, and haven't worked out the waveform part either yet)

If anyone wants to take the reigns or has anything to add please feel free to leave a comment.

And the code in the jxs patch is here (as I'm unsure if it attaches the code inside the compressed maxpat):

<jittershader name="stripes">
    <param name="modelViewProjectionMatrix" type="mat4" state="MODELVIEW_PROJECTION_MATRIX" />
    <param name="textureMatrix0" type="mat4" state="TEXTURE0_MATRIX" />
    <param name="position" type="vec3" state="POSITION" />
    <param name="texcoord" type="vec2" state="TEXCOORD" />
    <param name="iResolution" type="vec2" state="TEXDIM0" />
    <param name="iMouse" type="vec4" default="0 0 0 0" />
    <param name="iTime" type="float" default="0" />
    <param name="dummytex" type="int" default="0" />
    <param name="iChannel0" type="int" default="1" />
    <param name="iChannel1" type="int" default="2" />
    <param name="iChannel2" type="int" default="3" />
    <param name="iChannel3" type="int" default="4" />
     <param name="ffttex" type="int" default="1" />
     <param name="music1" type="float" default="0.0" />
    <param name="music2" type="float" default="0.0" />
    <language name="glsl" version="1.5">
        <bind param="modelViewProjectionMatrix" program="vp" />
        <bind param="textureMatrix0" program="vp" />
        <bind param="position" program="vp" />
        <bind param="texcoord" program="vp" />
        <bind param="iTime" program="fp" />
        <bind param="iMouse" program="fp" />
        <bind param="iResolution" program="fp" />
        <bind param="dummytex" program="fp" />
        <bind param="iChannel0" program="fp" />
        <bind param="iChannel1" program="fp" />
        <bind param="iChannel2" program="fp" />
        <bind param="iChannel3" program="fp" />
         <bind param="music1" program="fp" />
        <bind param="music2" program="fp" />
        <bind param="ffttex" program="fp" />
        <program name="vp" type="vertex"  >
        <![CDATA[
            #version 330 core
             in vec3 position;
            in vec2 texcoord;
            out jit_PerVertex {
                vec2 texcoord;
            } jit_out;
            uniform mat4 modelViewProjectionMatrix;
            uniform mat4 textureMatrix0;
             void main(void) {
                gl_Position = modelViewProjectionMatrix*vec4(position, 1.);
                jit_out.texcoord = vec2(textureMatrix0*vec4(texcoord, 0., 1.));
            }
        ]]>
        </program>      
        <program name="fp" type="fragment"  >
        <![CDATA[
            #version 330 core
            in jit_PerVertex {
                vec2 texcoord;
            } jit_in;
            out vec4 outColor;
                        uniform float iTime;
            uniform float music1;
            uniform float music2;
            uniform vec2 iResolution;
            uniform vec4 iMouse;
            uniform sampler2DRect dummytex;
            uniform samplerJit0 tex;
            //uniform samplerBuffer iChannel0;
            uniform sampler2DRect iChannel0;
            uniform sampler2DRect iChannel1;
            uniform samplerBuffer ffttex;
            //uniform sampler iChannel2;
            //uniform sampler iChannel3;
            // <<<<<<<<< START SHADER CODE:
            vec3 B2_spline(vec3 x) { // returns 3 B-spline functions of degree 2
            vec3 t = 3.0 * x;
            vec3 b0 = step(0.0, t)     * step(0.0, 1.0-t);
        vec3 b1 = step(0.0, t-1.0) * step(0.0, 2.0-t);
        vec3 b2 = step(0.0, t-2.0) * step(0.0, 3.0-t);
        return 0.5 * (
            b0 * pow(t, vec3(2.0)) +
            b1 * (-2.0*pow(t, vec3(2.0)) + 6.0*t - 3.0) + 
            b2 * pow(3.0-t,vec3(2.0))
    );
}
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    // create pixel coordinates
    vec2 uv = fragCoord.xy / iResolution.xy;
    float fVBars = 128.;
        float fHSpacing = 1.00;
        float fHFreq = (uv.x * 3.14);
    float squarewave = sign(sin(fHFreq*fVBars)+1.0-fHSpacing);
        float x = floor(uv.x * fVBars)/fVBars;
        float fSample = texture( iChannel0, vec2(abs(2.0 * x - 1.0), 0.25)).x;
     float fft = squarewave * fSample* 0.5;
        float fHBars = 100.0;
        float fVSpacing = 0.180;
        float fVFreq = (uv.y * 3.14);
    fVFreq = sign(sin(fVFreq * fHBars)+1.0-fVSpacing);
        vec2 centered = vec2(1.0) * uv - vec2(1.0);
        float t = iTime / 100.0;
        float polychrome = 1.0;
        vec3 spline_args = fract(vec3(polychrome*uv.x-t) + vec3(0.0, -1.0/3.0, -2.0/3.0));
        vec3 spline = B2_spline(spline_args);
        float f = abs(centered.y);
        vec3 base_color  = vec3(1.0, 1.0, 1.0) - f*spline;
        vec3 flame_color = pow(base_color, vec3(3.0));
        float tt = 0.3 - uv.y;
        float df = sign(tt);
        df = (df + 1.0)/0.5;
        vec3 col = flame_color * vec3(1.0 - step(fft, abs(0.3-uv.y))) * vec3(fVFreq);
        col -= col * df * 0.180;
     // output final color
    fragColor = vec4(col,1.0);
}
// <<<<<<<<< END SHADER CODE.
        void main(void) {                
                mainImage(outColor, jit_in.texcoord.st);
            }
        ]]>
        </program>
    </language>
</jittershader>