uniform sampler2D texture_data;

uniform vec2 crop;

void main()
{
    vec2 tcfull = vec2(vertex_texcoord.x, 1.0 - vertex_texcoord.y);
    if (tcfull.x > crop.x || tcfull.y > crop.y) discard;
    vec4 texel = texture(texture_data, tcfull);
    texel.a = 0.5;
    frag_color = texel;
}