Using libGdx and writing shaders without hardcoding

[Bevilacqua]

I tried to get it to work but it doesn't display at all. There are no compile errors.

Vertex

uniform mat4 u_progTrans;

//SpriteBatch input
attribute vec4 Position;
attribute vec2 TexCoord;
attribute vec4 Color;

//Fragment output (varying)
varying vec2 vTexCoord;
varying vec4 vColor;

//Main
void main() {
    vColor = Color;
    vTexCoord = TexCoord;
    gl_Position = u_progTrans * Position;

}

Fragment

#ifdef GL_ES
#define LOWP lowp
precision mediump float;
#else 
#define LOWP
#endif

//Texture
uniform sampler2D u_texture;

//Input form vertex (varying)
varying vec2 vTexCoord;
varying LOWP vec4 vColor;

//Main
void main() {
    //Sample the texture
    vec4 texColor = texture2D(u_texture, vTexCoord);

    //Color modification
    texColor.rgb = 1.0 - texColor.rgb;

    //Output
    gl_FragColor = texColor * vColor;
}