diff --git a/scene/3d/cpu_particles.cpp b/scene/3d/cpu_particles.cpp index 39abae88297..3eb3062282f 100644 --- a/scene/3d/cpu_particles.cpp +++ b/scene/3d/cpu_particles.cpp @@ -694,15 +694,28 @@ void CPUParticles::_particles_process(float p_delta) { p.velocity = rot * parameters[PARAM_INITIAL_LINEAR_VELOCITY] * Math::lerp(1.0f, float(Math::randf()), randomness[PARAM_INITIAL_LINEAR_VELOCITY]); } else { //initiate velocity spread in 3D - float angle1_rad = Math::atan2(direction.x, direction.z) + (Math::randf() * 2.0 - 1.0) * Math_PI * spread / 180.0; - float angle2_rad = Math::atan2(direction.y, Math::abs(direction.z)) + (Math::randf() * 2.0 - 1.0) * (1.0 - flatness) * Math_PI * spread / 180.0; + float angle1_rad = (Math::randf() * 2.0 - 1.0) * Math_PI * spread / 180.0; + float angle2_rad = (Math::randf() * 2.0 - 1.0) * (1.0 - flatness) * Math_PI * spread / 180.0; Vector3 direction_xz = Vector3(Math::sin(angle1_rad), 0, Math::cos(angle1_rad)); Vector3 direction_yz = Vector3(0, Math::sin(angle2_rad), Math::cos(angle2_rad)); - direction_yz.z = direction_yz.z / MAX(0.0001, Math::sqrt(ABS(direction_yz.z))); //better uniform distribution - Vector3 direction = Vector3(direction_xz.x * direction_yz.z, direction_yz.y, direction_xz.z * direction_yz.z); - direction.normalize(); - p.velocity = direction * parameters[PARAM_INITIAL_LINEAR_VELOCITY] * Math::lerp(1.0f, float(Math::randf()), randomness[PARAM_INITIAL_LINEAR_VELOCITY]); + Vector3 spread_direction = Vector3(direction_xz.x * direction_yz.z, direction_yz.y, direction_xz.z * direction_yz.z); + Vector3 direction_nrm = direction; + if (direction_nrm.length_squared() > 0) { + direction_nrm.normalize(); + } else { + direction_nrm = Vector3(0, 0, 1); + } + // rotate spread to direction + Vector3 binormal = Vector3(0.0, 1.0, 0.0).cross(direction_nrm); + if (binormal.length_squared() < 0.00000001) { + // direction is parallel to Y. Choose Z as the binormal. + binormal = Vector3(0.0, 0.0, 1.0); + } + binormal.normalize(); + Vector3 normal = binormal.cross(direction_nrm); + spread_direction = binormal * spread_direction.x + normal * spread_direction.y + direction_nrm * spread_direction.z; + p.velocity = spread_direction * parameters[PARAM_INITIAL_LINEAR_VELOCITY] * Math::lerp(1.0f, float(Math::randf()), randomness[PARAM_INITIAL_LINEAR_VELOCITY]); } float base_angle = (parameters[PARAM_ANGLE] + tex_angle) * Math::lerp(1.0f, p.angle_rand, randomness[PARAM_ANGLE]);