playcanvas/build/playcanvas/src/scene/shader-lib/glsl/chunks/internal/frag/packHalf.d.ts

PlayCanvas WebGL game engine

declare const _default: "\n\n#if defined(PLATFORM_ANDROID)\n\n    // Software pack of one f32 -> f16 (low 16 bits). Ties-to-even, full subnormals.\n    uint floatToHalf(float a) {\n        uint u    = floatBitsToUint(a);\n        uint sign = (u >> 16u) & 0x8000u;\n        uint absu = u & 0x7FFFFFFFu;\n        uint man  = u & 0x007FFFFFu;\n        int  e32  = int((u >> 23u) & 0xFFu) - 127;\n        \n        // NaN / Inf\n        if ((absu & 0x7F800000u) == 0x7F800000u) {\n            bool isnan = (man != 0u);\n            return sign | (isnan ? 0x7E00u : 0x7C00u);\n        }\n        \n        // Overflow to Inf\n        if (e32 > 15) return sign | 0x7C00u;\n        \n        // Normal half\n        if (e32 >= -14) {\n            uint he  = uint(e32 + 15);\n            uint hm  = man >> 13u;\n            uint rem = man & 0x1FFFu;\n            uint add = (rem > 0x1000u || (rem == 0x1000u && (hm & 1u) == 1u)) ? 1u : 0u;\n            hm = (hm + add) & 0x3FFu;\n            if ((hm & 0x400u) != 0u) {\n                hm = 0u; he = he + 1u;\n                if (he >= 31u) return sign | 0x7C00u;\n            }\n            return sign | (he << 10u) | hm;\n        }\n        \n        // Subnormals\n        if (e32 >= -24) {\n            uint s      = uint(-(e32 + 1));\n            uint mnorm  = 0x00800000u | man;\n            uint hm     = mnorm >> s;\n            uint mask   = (1u << s) - 1u;\n            uint rem    = mnorm & mask;\n            uint halfBt = 1u << (s - 1u);\n            uint add    = (rem > halfBt || (rem == halfBt && (hm & 1u) == 1u)) ? 1u : 0u;\n            hm = hm + add;\n            if (hm >= 0x400u) return sign | (1u << 10u);\n            return sign | hm;\n        }\n        \n        // Underflow to signed zero\n        return sign;\n    }\n\n    // Hybrid pack: software for subnormals, builtin for normal range\n    uint packHalf2x16Safe(vec2 v) {\n        // Convert the input floats to their 32-bit IEEE-754 bit patterns.\n        // We'll inspect the exponent bits directly to determine their numeric range.\n        uint u_x  = floatBitsToUint(v.x);\n        uint u_y  = floatBitsToUint(v.y);\n        \n        // Extract the unbiased exponent for each component (float32 uses bias = 127).\n        // e32 = exponent - 127  \u21D2  actual power of two for each value.\n        int  e32_x = int((u_x >> 23u) & 0xFFu) - 127;\n        int  e32_y = int((u_y >> 23u) & 0xFFu) - 127;\n        \n        // -------------------------------------------------------------------------\n        // Detect values that would become *subnormal* (or zero) in float16.\n        //\n        //   e32 < -14  \u21D4  |value| < 2^-14 \u2248 6.1035e-5\n        //\n        // Many mobile GPUs (including Adreno and Mali) mishandle half-precision\n        // subnormals\u2014typically flushing them to zero or rounding incorrectly.\n        // To preserve correct rounding and sign, we use the software conversion\n        // path (floatToHalf) for these small magnitudes.\n        //\n        // The software branch runs very rarely (<0.1% of typical values for\n        // normalized scene data) and costs only a few ALU instructions, so the\n        // performance impact is negligible while avoiding visible precision loss.\n        // -------------------------------------------------------------------------\n        if (e32_x < -14 || e32_y < -14) {\n            // Convert both components with the reference software routine\n            // and pack into a 32-bit uint: low 16 bits = x, high 16 bits = y.\n            return (floatToHalf(v.y) << 16u) | floatToHalf(v.x);\n        }\n        \n        // Normal range: use the fast hardware builtin\n        return packHalf2x16(v);\n    }\n\n#else\n\n    // On non-Android platforms, use builtin directly (no subnormal workaround needed)\n    uint packHalf2x16Safe(vec2 v) {\n        return packHalf2x16(v);\n    }\n\n#endif\n";
export default _default;