another shader from shadertoy

    Feb 19 2019 | 7:08 am
    hello eveyone I try to translate this very simple shadertoy to but it's not working, eveything is black.
    Can you tell me where is the problem?
    this is my shader :
    <jittershader name="default"> <description> Default Slab </description> <param name="iChannel0" type="int" default="0" />
    <param name="iResolution" type="vec2" state="VIEWPORT" />
    <language name="glsl" version="1.2">
    <bind param="iChannel0" program="fp" />
    <bind param="iResolution" program="vp" />
    <program name="vp" type="vertex"> <![CDATA[
    varying vec2 texcoord; uniform vec2 iResolution;
    void main (void) { gl_Position = ftransform(); texcoord = vec2(gl_TextureMatrix[0] * gl_MultiTexCoord0); iResolution = vec2 (abs(gl_TextureMatrix[0][0][0]),abs(gl_TextureMatrix[0][1][1])); } ]]> </program> <program name="fp" type="fragment"> <![CDATA[ // FRAGMENT SHADER
    varying vec2 texcoord; uniform float iTime;
    uniform sampler2DRect iChannel0;
    uniform vec2 iResolution;
    vec2 rand( vec2 p ) { p = vec2( dot(p,vec2(127.1,311.7)), dot(p,vec2(269.5,183.3)) ); return fract(sin(p)*43758.5453); }
    void main(void) { vec2 uv = texcoord/iResolution.xy;
    float strength = cos(iTime)*0.1;
    gl_FragColor = texture2DRect( iChannel0, uv + strength*(rand(uv)-0.5)); }
    ]]> </program> </language> </jittershader>