playcanvas

Version:
PlayCanvas WebGL game engine
83 lines (60 loc) • 1.77 kB
JavaScript
var gsplatPS = /* wgsl */ `

#ifndef DITHER_NONE
    #include "bayerPS"
    #include "opacityDitherPS"
    varying id: f32;
#endif

#ifdef PICK_PASS
    #include "pickPS"
#endif

#if defined(SHADOW_PASS) || defined(PICK_PASS) || defined(PREPASS_PASS)
    uniform alphaClip: f32;
#endif

#ifdef PREPASS_PASS
    varying vLinearDepth: f32;
    #include "floatAsUintPS"
#endif

// Fast approximate e^x based on https://nic.schraudolph.org/pubs/Schraudolph99.pdf
const EXP_A: f32      = 12102203.0;   // ≈ 2^23 / ln(2)
const EXP_BC_RMS: i32 = 1064866808;   // (127 << 23) - 60801 * 8
fn fastExp(x: f32) -> f32 {
    var i: i32 = i32(EXP_A * x) + EXP_BC_RMS;
    return bitcast<f32>(i);
}

varying gaussianUV: vec2f;
varying gaussianColor: vec4f;

@fragment
fn fragmentMain(input: FragmentInput) -> FragmentOutput {
    var output: FragmentOutput;

    let A: f32 = dot(gaussianUV, gaussianUV);
    if (A > 1.0) {
        discard;
        return output;
    }

    // evaluate alpha
    var alpha: f32 = fastExp(-A * 4.0) * gaussianColor.a;

    #if defined(SHADOW_PASS) || defined(PICK_PASS) || defined(PREPASS_PASS)
        if (alpha < uniform.alphaClip) {
            discard;
            return output;
        }
    #endif

    #ifdef PICK_PASS

        output.color = getPickOutput();

    #elif SHADOW_PASS

        output.color = vec4f(0.0, 0.0, 0.0, 1.0);

    #elif PREPASS_PASS

        output.color = float2vec4(vLinearDepth);

    #else

        if (alpha < (1.0 / 255.0)) {
            discard;
            return output;
        }

        #ifndef DITHER_NONE
            opacityDither(&alpha, id * 0.013);
        #endif

        output.color = vec4f(input.gaussianColor.xyz * alpha, alpha);
    #endif

    return output;
}`;

export { gsplatPS as default };