playcanvas/build/playcanvas.dbg/src/scene/shader-lib/wgsl/chunks/common/frag/float-as-uint.js

PlayCanvas WebGL game engine

// Chunk that allows us to store all 32bits of float in a single RGBA8 texture without any loss of
// precision. The float value is encoded to RGBA8 and decoded back to float. Used as a fallback
// for platforms that do not support float textures but need to render to a float texture (without
// filtering)
var floatAsUintPS = /* wgsl */ `

#ifndef FLOAT_AS_UINT
#define FLOAT_AS_UINT

// encode float value to RGBA8 representation (0.0-1.0 range)
fn float2uint(value: f32) -> vec4f {
    let intBits = bitcast<u32>(value);
    return vec4f(
        f32((intBits >> 24u) & 0xffu),
        f32((intBits >> 16u) & 0xffu),
        f32((intBits >> 8u) & 0xffu),
        f32(intBits & 0xffu)
    ) / 255.0;
}

// decode RGBA8 value to float
fn uint2float(value: vec4f) -> f32 {
    let rgba_u32 = vec4<u32>(value * 255.0);
    let intBits: u32 =
        (rgba_u32.r << 24u) |
        (rgba_u32.g << 16u) |
        (rgba_u32.b << 8u)  |
         rgba_u32.a;
    return bitcast<f32>(intBits);
}

// store a single float value in vec4, assuming either RGBA8 or float renderable texture
fn float2vec4(value: f32) -> vec4f {
    #if defined(CAPS_TEXTURE_FLOAT_RENDERABLE)
        return vec4f(value, 1.0, 1.0, 1.0);
    #else
        return float2uint(value);
    #endif
}

#endif // FLOAT_AS_UINT
`;

export { floatAsUintPS as default };