请问一般的阴影字用的都是什么算法？ - Project1

Flexible & Accurate: Filters

Use a texel filter either on the texture on the CPU side, or if you are using programmable pipeline OpenGL, directly in the fragment shader.

The idea of a filter is simply that you run through a 2D loop to process every texel. If it is white, then you run through an inner 2D loop for each of its surrounding pixels in some radius, and adapt accordingly. This is also known as a box filter, though if you include the radius check, it is really a circular filter -- which avoids axis-al artifacting.

A faster way to do this is to precalculate the set of offsets from each central pixel that you check; this way, you needn't run a square root for every pixel surrounding a given pixel. You want to keep complexity down to `O(texWidth*texHeight) rather than O(texWidth*texHeight*filterRadius*filterRadius), in other words.

Easy: Multiple renders

Another way to achieve the effect would be not to scale the text, but instead to render your red outline at each of eight (or more) directions, each slightly offset from the original in that direction:

\|/
--+--
/|\

By offsetting each of the red versions like this, you would get a fairly uniform outer edge around your original text. Bear in mind that when shifting diagonally, you should use the same vector magnitude as when you shift horizontally or vertically, rather than simply offsetting by the same x and y values (which leads to a approximatlely 1.4x further length -- basic trig).

FYI

This sort of effect is known as dilation, and is sometimes performed via Minkowski Summation, which is the vector-based (continuous) approach to the pixel-based (quantised) box filter I described above.

#====================================================================== 
# 脚本来自[url]www.66rpg.com[/url]，使用请保留此信息 
# 作者：SailCat；升级：柳柳；最后升级日期：2006年4月30日 
#====================================================================== 
class Bitmap 
  unless $OK 
    alias sailcat_draw_text draw_text unless method_defined?(:sailcat_draw_text)
    def draw_text(p1, p2, p3 = 0, p4 = 3, p5 = nil, p6 = 0, p7 = 3, p8 = nil) 
      case p1 
      when Numeric 
        x = p1 
        y = p2 
        width = p3 
        height = p4 
        text = p5 
        align = p6 
        shadow_direction = p7 
        shadow_color = p8 
        if shadow_color.nil? 
          shadow_color = Color.new(0, 0, 0, self.font.color.alpha * 0.67) 
        end 
      when Rect 
        x = p1.x 
        y = p1.y 
        width = p1.width 
        height = p1.height 
        text = p2 
        align = p3 
        shadow_direction = p4 
        shadow_color = p5 
        if shadow_color.nil? 
          shadow_color = Color.new(0, 0, 0, self.font.color.alpha * 0.67) 
        end 
      end 
      color_temp = self.font.color.clone 
      if shadow_direction != 0 
        self.font.color = shadow_color 
        case shadow_direction 
        when 1 
          sailcat_draw_text(x-1, y+1, width, height, text, align) 
        when 3 
          sailcat_draw_text(x+1, y+1, width, height, text, align) 
        when 7 
          sailcat_draw_text(x-1, y-1, width, height, text, align) 
        when 9 
          sailcat_draw_text(x+1, y-1, width, height, text, align) 
        end 
        self.font.color = color_temp 
      end 
      $OK = true 
      sailcat_draw_text(x, y, width, height, text, align) 
    end 
  end 
end

#====================================================================== 


# 脚本来自[url]www.66rpg.com[/url]，使用请保留此信息 


# 作者：SailCat；升级：柳柳；最后升级日期：2006年4月30日 


#====================================================================== 


class Bitmap 


  unless $OK 


    alias sailcat_draw_text draw_text unless method_defined?(:sailcat_draw_text)


    def draw_text(p1, p2, p3 = 0, p4 = 3, p5 = nil, p6 = 0, p7 = 3, p8 = nil) 


      case p1 


      when Numeric 


        x = p1 


        y = p2 


        width = p3 


        height = p4 


        text = p5 


        align = p6 


        shadow_direction = p7 


        shadow_color = p8 


        if shadow_color.nil? 


          shadow_color = Color.new(0, 0, 0, self.font.color.alpha * 0.67) 


        end 


      when Rect 


        x = p1.x 


        y = p1.y 


        width = p1.width 


        height = p1.height 


        text = p2 


        align = p3 


        shadow_direction = p4 


        shadow_color = p5 


        if shadow_color.nil? 


          shadow_color = Color.new(0, 0, 0, self.font.color.alpha * 0.67) 


        end 


      end 


      color_temp = self.font.color.clone 


      if shadow_direction != 0 


        self.font.color = shadow_color 


        case shadow_direction 


        when 1 


          sailcat_draw_text(x-1, y+1, width, height, text, align) 


        when 3 


          sailcat_draw_text(x+1, y+1, width, height, text, align) 


        when 7 


          sailcat_draw_text(x-1, y-1, width, height, text, align) 


        when 9 


          sailcat_draw_text(x+1, y-1, width, height, text, align) 


        end 


        self.font.color = color_temp 


      end 


      $OK = true 


      sailcat_draw_text(x, y, width, height, text, align) 


    end 


  end 


end