Method sample

src/testrender/shading.cpp:458–509

    }

    virtual float sample(const OSL::ShaderGlobals& sg, float rx, float ry, float rz, OSL::Dual2<OSL::Vec3>& wi, float& pdf) const {
    	const Vec3 wo_l = tf.tolocal(-sg.I);
    	const float cosNO = wo_l.z;
    	if (!(cosNO > 0)) return pdf = 0;
        const Vec3 m = sampleMicronormal(wo_l, rx, ry);
        const float cosMO = m.dot(wo_l);
        const float F = fresnel_dielectric(cosMO, eta);
        if (Refract == 0 || (Refract == 2 && rz < F)) {
            // measure fresnel to decide which lobe to sample
            const Vec3 wi_l = (2.0f * cosMO) * m - wo_l;
            const float D = evalD(m);
            const float Lambda_o = evalLambda(wo_l);
            const float Lambda_i = evalLambda(wi_l);

            const float G2 = evalG2(Lambda_o, Lambda_i);
            const float G1 = evalG1(Lambda_o);

            wi = tf.toworld(wi_l);

            pdf = (G1 * D * 0.25f) / cosNO;
            float out = G2 / G1;
            if (Refract == 2) {
                pdf *= F;
                return out;
            } else
                return F * out;
        } else {
            const Vec3 M = tf.toworld(m);
            float Ft = fresnel_refraction (sg.I, M, eta, wi);
            const Vec3 wi_l = tf.tolocal(wi.val());
            const float cosHO = m.dot(wo_l);
            const float cosHI = m.dot(wi_l);
            const float D = evalD(m);
            const float Lambda_o = evalLambda(wo_l);
            const float Lambda_i = evalLambda(wi_l);

            const float G2 = evalG2(Lambda_o, Lambda_i);
            const float G1 = evalG1(Lambda_o);

            const Vec3 ht = -(eta * wi_l + wo_l);
            const float invHt2 = 1.0f / ht.dot(ht);

            pdf = (fabsf(cosHI * cosHO) * (eta * eta) * (G1 * D) * invHt2) / fabsf(wo_l.z);
            float out = G2 / G1;
            if (Refract == 2) {
                pdf *= Ft;
                return out;
            } else
                return Ft * out;
        }
        return pdf = 0;
    }

private:
    static float SQR(float x) {