rustial-renderer-wgpu 1.0.0

Pure WGPU renderer for the rustial 2.5D map engine
Documentation 
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// Fill-extrusion shader with directional lighting and fog.

struct Uniforms {
    view_proj:  mat4x4<f32>,
    fog_color:  vec4<f32>,
    eye_pos:    vec4<f32>,
    fog_params: vec4<f32>,   // (start, end, density, 0)
};

struct VertexInput {
    @location(0) position: vec3<f32>,
    @location(1) normal:   vec3<f32>,
    @location(2) color:    vec4<f32>,
};

struct VertexOutput {
    @builtin(position) clip_position: vec4<f32>,
    @location(0) normal:    vec3<f32>,
    @location(1) color:     vec4<f32>,
    @location(2) world_pos: vec3<f32>,
};

@group(0) @binding(0)
var<uniform> u: Uniforms;

@vertex
fn vs_main(in: VertexInput) -> VertexOutput {
    var out: VertexOutput;
    out.clip_position = u.view_proj * vec4<f32>(in.position, 1.0);
    out.normal    = in.normal;
    out.color     = in.color;
    out.world_pos = in.position;
    return out;
}

@fragment
fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
    // --- Directional light ---
    // Fixed sun direction: upper-left, 45° altitude.
    let sun_dir = normalize(vec3<f32>(-0.5, 0.5, 0.707));
    let n = normalize(in.normal);

    // Lambertian diffuse.
    let ndotl = max(dot(n, sun_dir), 0.0);
    // Soft fill light from opposite side to reduce harsh shadows.
    let fill_dir = normalize(vec3<f32>(sun_dir.y, -sun_dir.x, max(0.25, sun_dir.z * 0.6)));
    let fill = max(dot(n, fill_dir), 0.0);
    // Ambient + diffuse + fill.
    let lit = clamp(
        in.color.rgb * (0.55 + 0.50 * ndotl + 0.12 * fill),
        vec3<f32>(0.0),
        vec3<f32>(1.0),
    );

    // --- Horizon fog ---
    let dx = in.world_pos.x - u.eye_pos.x;
    let dy = in.world_pos.y - u.eye_pos.y;
    let ground_dist = sqrt(dx * dx + dy * dy);
    let fog_start = u.fog_params.x;
    let fog_end   = u.fog_params.y;
    let density   = u.fog_params.z;
    let fog_t = clamp(
        (ground_dist - fog_start) / max(fog_end - fog_start, 0.001),
        0.0, 1.0,
    ) * density;
    let fog_mix = fog_t * 0.7;

    let blended_rgb = mix(lit, u.fog_color.rgb, fog_mix);
    let blended_a   = in.color.a * (1.0 - fog_mix);
    return vec4<f32>(blended_rgb, blended_a);
}