lingo3d/lib/engine/renderLoop/effectComposer/ssrEffect/material/shader/helperFunctions.js

Lingo3D is a React/Vue 3d game development framework that ships with a complete visual editor

export default `// source: https://github.com/mrdoob/three.js/blob/dev/examples/js/shaders/SSAOShader.js
vec3 getViewPosition(const float depth) {
    float clipW = _projectionMatrix[2][3] * depth + _projectionMatrix[3][3];
    vec4 clipPosition = vec4((vec3(vUv, depth) - 0.5) * 2.0, 1.0);
    clipPosition *= clipW;
    return (_inverseProjectionMatrix * clipPosition).xyz;
}

// source: https://github.com/mrdoob/three.js/blob/342946c8392639028da439b6dc0597e58209c696/examples/js/shaders/SAOShader.js#L123
float getViewZ(const in float depth) {
#ifdef PERSPECTIVE_CAMERA
    return perspectiveDepthToViewZ(depth, cameraNear, cameraFar);
#else
    return orthographicDepthToViewZ(depth, cameraNear, cameraFar);
#endif
}

// credits for transforming screen position to world position: https://discourse.threejs.org/t/reconstruct-world-position-in-screen-space-from-depth-buffer/5532/2
vec3 screenSpaceToWorldSpace(const vec2 uv, const float depth) {
    vec4 ndc = vec4(
        (uv.x - 0.5) * 2.0,
        (uv.y - 0.5) * 2.0,
        (depth - 0.5) * 2.0,
        1.0);

    vec4 clip = _inverseProjectionMatrix * ndc;
    vec4 view = cameraMatrixWorld * (clip / clip.w);

    return view.xyz;
}

// vec2 worldSpaceToScreenSpace(vec3 worldPos){
//     vec4 ssPos = _projectionMatrix * inverse(cameraMatrixWorld) * vec4(worldPos, 1.0);
//     ssPos.xy /= ssPos.w;
//     ssPos.xy = ssPos.xy * 0.5 + 0.5;

//     return ssPos.xy;
// }

#define Scale (vec3(0.8, 0.8, 0.8))
#define K     (19.19)

vec3 hash(vec3 a) {
    a = fract(a * Scale);
    a += dot(a, a.yxz + K);
    return fract((a.xxy + a.yxx) * a.zyx);
}

// source: https://github.com/blender/blender/blob/594f47ecd2d5367ca936cf6fc6ec8168c2b360d0/source/blender/gpu/shaders/material/gpu_shader_material_fresnel.glsl
float fresnel_dielectric_cos(float cosi, float eta) {
    /* compute fresnel reflectance without explicitly computing
     * the refracted direction */
    float c = abs(cosi);
    float g = eta * eta - 1.0 + c * c;
    float result;

    if (g > 0.0) {
        g = sqrt(g);
        float A = (g - c) / (g + c);
        float B = (c * (g + c) - 1.0) / (c * (g - c) + 1.0);
        result = 0.5 * A * A * (1.0 + B * B);
    } else {
        result = 1.0; /* TIR (no refracted component) */
    }

    return result;
}

// source: https://github.com/blender/blender/blob/594f47ecd2d5367ca936cf6fc6ec8168c2b360d0/source/blender/gpu/shaders/material/gpu_shader_material_fresnel.glsl
float fresnel_dielectric(vec3 Incoming, vec3 Normal, float eta) {
    /* compute fresnel reflectance without explicitly computing
     * the refracted direction */

    float cosine = dot(Incoming, Normal);
    return min(1.0, 5.0 * fresnel_dielectric_cos(cosine, eta));
}`;
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