camera.rb

class Camera
  attr_reader :position, :target, :horizontal_angle, :vertical_angle
  def initialize(parent_window)
    @parent_window = parent_window
    @position = Vector3D.new(2.0, 2.5, 5.0)
    @target = Vector3D.new(0.0, 0.0, 0.0)
    @up = Vector3D.new(0.0, 1.0, 0.0)
    @ratio, @fovy, @far, @near = @parent_window.width.to_f / @parent_window.height.to_f, 60.0, 1000.0, 0.01
    @horizontal_angle = 0.0
    @vertical_angle = 0.0
    @distance = 3.0
    @speed = 0.08
    @angle_speed = 1.9
    @collision_box = Box2D.new(Vector3D.new(@position.x - 0.5, @position.y, @position.z - 0.5), 1.0, 1.0)
    @parent_window.mouse_x, @parent_window.mouse_y = @parent_window.width / 2, @parent_window.height / 2
    @last_mouse_x, @last_mouse_y = @parent_window.mouse_x, @parent_window.mouse_y
    @mouse_sensitivity = 0.1

    @on_ground = false
    @gravity = -0.0075
    @velocity_y = 0.0

    adjust_target
  end

  def update
    speed = @speed

    old_x, old_z = @position.x, @position.z

    handle_jump

    # diagonal speed
    if @parent_window.button_down?(Gosu::KbW) or @parent_window.button_down?(Gosu::KbS)
      if @parent_window.button_down?(Gosu::KbA) or @parent_window.button_down?(Gosu::KbD)
        speed *= 0.7
      end
    end

    if @parent_window.button_down?(Gosu::KbW)
      @position.x += speed * Math::cos(@horizontal_angle * Math::PI / 180.0)
      @position.z += speed * Math::sin(@horizontal_angle * Math::PI / 180.0)
    elsif @parent_window.button_down?(Gosu::KbS)
      @position.x -= speed * Math::cos(@horizontal_angle * Math::PI / 180.0)
      @position.z -= speed * Math::sin(@horizontal_angle * Math::PI / 180.0)
    end

    if @parent_window.button_down?(Gosu::KbA)
      @position.x += speed * Math::cos((@horizontal_angle - 90.0) * Math::PI / 180.0)
      @position.z += speed * Math::sin((@horizontal_angle - 90.0) * Math::PI / 180.0)
    elsif @parent_window.button_down?(Gosu::KbD)
      @position.x -= speed * Math::cos((@horizontal_angle - 90.0) * Math::PI / 180.0)
      @position.z -= speed * Math::sin((@horizontal_angle - 90.0) * Math::PI / 180.0)
    end

    # ANGLE
    if @parent_window.button_down?(Gosu::KbUp)
      @vertical_angle += @angle_speed
    elsif @parent_window.button_down?(Gosu::KbDown)
      @vertical_angle -= @angle_speed
    end

    if @parent_window.button_down?(Gosu::KbLeft)
      @horizontal_angle -= @angle_speed
    elsif @parent_window.button_down?(Gosu::KbRight)
      @horizontal_angle += @angle_speed
    end

    # ANGLE WITH MOUSE
    if @parent_window.mouse_x != @last_mouse_x
      @horizontal_angle += (@parent_window.mouse_x - @last_mouse_x) * @mouse_sensitivity
      @parent_window.mouse_x = @parent_window.width / 2
      @last_mouse_x = @parent_window.mouse_x
    end

    if @parent_window.mouse_y != @last_mouse_y
      @vertical_angle -= (@parent_window.mouse_y - @last_mouse_y) * @mouse_sensitivity
      @parent_window.mouse_y = @parent_window.height / 2
      @last_mouse_y = @parent_window.mouse_y
    end

    @vertical_angle = -90.0 if @vertical_angle < -90.0
    @vertical_angle = 90.0 if @vertical_angle > 90.0

    # collision check
    @collision_box.origin.x = @position.x - 0.5
    @collision_box.origin.z = @position.z - 0.5

    if @parent_window.map.block?(@collision_box)
      if !@parent_window.map.block?(Box2D.new(Vector3D.new(@position.x - 0.5, @position.y, old_z - 0.5), 1.0, 1.0))
        @position.z = old_z
      elsif !@parent_window.map.block?(Box2D.new(Vector3D.new(old_x - 0.5, @position.y, @position.z - 0.5), 1.0, 1.0))
        @position.x = old_x
      else # neither x or z are allowed
        @position.x = old_x
        @position.z = old_z
      end
    end

    adjust_target
  end

  def adjust_target
    @target.x = @position.x + @distance * Math::cos(@horizontal_angle * Math::PI / 180.0)
    @target.y = @position.y + @distance * Math::sin(@vertical_angle * Math::PI / 180.0)
    @target.z = @position.z + @distance * Math::sin(@horizontal_angle * Math::PI / 180.0)
  end

  def look
    glEnable(GL_DEPTH_TEST)
    glEnable(GL_TEXTURE_2D)
    #~ glClearColor(0.0, 1.0, 0.0, 0.0)
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)

    glEnable(GL_ALPHA_TEST)
    glAlphaFunc(GL_GREATER, 0)

    glMatrixMode(GL_PROJECTION)
    glLoadIdentity
    gluPerspective(@fovy, @ratio, @near, @far)

    glMatrixMode(GL_MODELVIEW)
    glLoadIdentity
    gluLookAt(@position.x, @position.y, @position.z, @target.x, @target.y, @target.z, @up.x, @up.y, @up.z)
  end

  def handle_jump
    if @parent_window.button_down? Gosu::KbSpace
      apply_force
    else
      reset_velocity
    end

    @velocity_y += @gravity
    @position.y += @velocity_y

    if @position.y < 2.5
      @position.y = 2.5
      @velocity_y = 0.0
      @on_ground = true
    end
  end

  def apply_force
    if @on_ground
      @velocity_y = 0.15
      @on_ground = false
    end
  end

  def reset_velocity
    if @velocity_y > 0.08
      @velocity_y = 0.08
    end
  end
end