shader_type particles;

void start()
{
    if (RESTART_CUSTOM)
    {
        CUSTOM = vec4(0.0);
    }
    if (RESTART_COLOR)
    {
        COLOR = vec4(0.0f, 0.0f, 0.0f, 1.0f);
    }
    if (RESTART_ROT_SCALE)
    {
        TRANSFORM[0].xyz = vec3(1.0f, 0.0f, 0.0f);
        TRANSFORM[1].xyz = vec3(0.0f, 1.0f, 0.0f);
        TRANSFORM[2].xyz = vec3(0.0f, 0.0f, 1.0f);
    }
    if (RESTART_POSITION)
    {
        TRANSFORM[3].xy = vec2(100.0f, 0.0f);
        TRANSFORM[3].zw = vec2(0.0f);
        TRANSFORM = EMISSION_TRANSFORM * TRANSFORM;
    }
    if (RESTART_VELOCITY)
    {
        VELOCITY.xy = vec2(100.0f, 0.0f);
        VELOCITY.z = 0.0f;
    }
}

void process()
{
    // Face direction of velocity
    TRANSFORM[1].xyz = normalize(VELOCITY);
    TRANSFORM[0].xyz = normalize(cross(TRANSFORM[1].xyz, TRANSFORM[2].xyz));
    TRANSFORM[2] = vec4(0.0f, 0.0f, 1.0f, 0.0f);
}