Constant SHADER 

pub const SHADER: &str = r#"// Image shader with direct data->viewport mapping

struct DirectUniforms {
    data_min: vec2<f32>,
    data_max: vec2<f32>,
    viewport_min: vec2<f32>,
    viewport_max: vec2<f32>,
    viewport_px: vec2<f32>,
}

@group(0) @binding(0)
var<uniform> uDirect: DirectUniforms;

@group(1) @binding(0)
var imgSampler: sampler;

@group(1) @binding(1)
var imgTex: texture_2d<f32>;

struct VSIn {
    @location(0) position: vec3<f32>,
    @location(3) uv: vec2<f32>,
}

struct VSOut {
    @builtin(position) clip_position: vec4<f32>,
    @location(0) uv: vec2<f32>,
}

@vertex
fn vs_main(input: VSIn) -> VSOut {
    var out: VSOut;
    let data_range = uDirect.data_max - uDirect.data_min;
    let viewport_range = uDirect.viewport_max - uDirect.viewport_min;
    let normalized = (input.position.xy - uDirect.data_min) / data_range;
    let ndc = uDirect.viewport_min + normalized * viewport_range;
    out.clip_position = vec4<f32>(ndc, 0.0, 1.0);
    out.uv = input.uv;
    return out;
}

@fragment
fn fs_main(input: VSOut) -> @location(0) vec4<f32> {
    let color = textureSample(imgTex, imgSampler, input.uv);
    return color;
}
"#;