西北师范大学计算机图形学实验报告一

Else
k += 2 * (dx - dy)
x += 1
EndIf
y += 1
EndWhile
EndIf
EndSub
5.清除线条
PrivateSubButton5_Click(ByValsenderAsSystem.Object,ByValeAsSystem.EventArgs)HandlesButton5.Click'清除
1.DGI+ DrawLine（）函数绘制直线
PrivateSubButton1_Click(ByValsenderAsSystem.Object,ByValeAsSystem.EventArgs)HandlesButton1.Click'DrawLine()函数画线
Dimx1, y1, x2, y2AsDouble
Ifk >= 0Then
k += a
Else
k += a + b
y += 1
EndIf
x += 1
EndWhile
Else
k = 0.5 * a + b
Whiley < y2
g.DrawEllipse(p,CInt(x),CInt(y), 1, 1)
Ifk >= 0Then
k += a + b
x += 1
三、实验内容：
在.net环境中利用DDA算法绘制直线、中点画线算法和Bresenham画线算法绘制直线，比较其与GDI+中提供的DrawLine ( )函数绘制的直线有何区别。
四、实验过程及步骤：
（包括程序界面设计、控件属性说明、程序代码和程序运行四部分）
（一）程序界面设计
（二）控件属性说明
例：
（三）程序代码
MessageBox.Show("请输入正确的坐标！", "警告！", MessageBoxButtons.OK, MessageBoxIcon.Warning)
Else
x1 = TextBox1.Text
y1 = TextBox2.Text
x2 = TextBox3.Text
y2 = TextBox4.Text
y2 =CDbl(TextBox4.Text)
dx = x2 - x1
dy = y2 - y1
x = x1
y = y1
EndIf
Ifdx > dyThen
k = 2 * dy - dx
Whilex < x2
g.DrawEllipse(p,CInt(x),CInt(y), 1, 1)
Ifk < 0Then
g.DrawLine(p,CInt(x1),CInt(y1),CInt(x2),CInt(y2))
EndIf
EndSub
2.DDA（数值微分）算法绘制直线
PrivateSubButton2_Click(ByValsenderAsSystem.Object,ByValeAsSystem.EventArgs)HandlesButton2.Click'DDA算法画线
MessageBox.Show("请输入正确的坐标！", "警告！", MessageBoxButtons.OK, MessageBoxIcon.Warning)
Else
x1 =CDbl(TextBox1.Text)
y1 =CDbl(TextBox2.Text)
x2 =CDbl(TextBox3.Text)
DimgAsGraphics = PictureBox1.CreateGraphics
DimpAsPen =NewPen(Color.Red, 1)
IfTextBox1.Text = ""OrTextBox2.Text = ""OrTextBox3.Text = ""OrTextBox4.Text = ""OrTextBox1.Text = TextBox3.TextOrTextBox2.Text = TextBox4.TextThen
Dimx1, y1, x2, y2, dx, dy, x, yAsDouble
DimiAsInteger
DimgAsGraphics = PictureBox1.CreateGraphics
DimpAsPen =NewPen(Color.Yellow, 1)
IfTextBox1.Text = ""OrTextBox2.Text = ""OrTextBox3.Text = ""OrTextBox4.Text = ""OrTextBox1.Text = TextBox3.TextOrTextBox2.Text = TextBox4.TextThen
PictureBox1.Refresh()
EndSub
6.退出程序
PrivateSubButton6_Click(ByValsenderAsSystem.Object,ByValeAsSystem.EventArgs)HandlesButton6.Click'退出
End
EndSub
（四）程序运行
（五）在.net环境中利用DDA算法绘制直线、中点画线算法和Bresenham画线算法绘制直线与GDI+中提供的DrawLine ( )函数绘制的直线区别主要表现在：
k += 2 * dy
Else
k += 2 * (dy - dx)
y = y + 1
EndIf
x = x + 1
EndWhile
Else
k = 2 * dx - dy
Whiley < y2
g.DrawEllipse(p,CInt(x),CInt(y), 1, 1)
Ifk < 0Then
k += 2 * dx
x += 1
Next
Else
Fori = 0TodyStep1
g.DrawEllipse(p,CInt(x),CInt(y), 1, 1)
x = x + dx / dy
y += 1
Next
EndIf
EndWhile
EndSub
3.中点画线算法绘制直线
PrivateSubButton3_Click(ByValsenderAsSystem.Object,ByValeAsSystem.EventArgs)HandlesButton3.Click'中点画线算法
y2 =CDbl(TextBox4.Text)
a = y1 - y2
b = x2 - x1
dx = x2 - x1
dy = y2 - y1
x = x1
y = y1
EndIf
Ifdx > dyThen
k = a + 0.5 * b
Whilex < x2
g.DrawEllipse(p,CInt(x),CInt(y), 1, 1)
Else
k += b
EndIf
y += 1
EndWhile
EndIf
EndSub
4.Bresenham画线算法绘制直线
PrivateSubButton4_Click(ByValsenderAsSystem.Object,ByValeAsSystem.EventArgs)HandlesButton4.Click'Bresenham画线算法
y2 =CDbl(TextBox4.Text)
dx = x2 - x1
dy = y2 - y1
x = x1
y = y1
EndIf
While(x < x2)
If(dx >= dy)Then
Fori = 0TodxStep1
g.DrawEllipse(p,CInt(x),CInt(y), 1, 1)
y = y + dy / dx
Dimx1, y1, x2, y2, dx, dy, x, y, kAsDouble
DimiAsInteger
DimgAsGraphics = PictureBox1.CreateGraphics
DimpAsPen =NewPen(Color.Blue, 1)
IfTextBox1.Text = ""OrTextBox2.Text = ""OrTextBox3.Text = ""OrTextBox4.Text = ""OrTextBox1.Text = TextBox3.TextOrTextBox2.Text = TextBox4.TextThen
西北师范大学学生实验报告
学院
地环学院
专业
地理信息系统
年级、班
08地信
学号
200875000203
姓名
陈晨
同组者
课程名称
计算机图形学
实验题目
直算法、中点画线算法和Bresenham画线算法。
二、实验准备：
学习绘制直线的DDA算法、中点画线算法和Bresenham画线算法，注意考虑不同斜率条件下算法的变化。
MessageBox.Show("请输入正确的坐标！", "警告！", MessageBoxButtons.OK, MessageBoxIcon.Warning)
Else
x1 =CDbl(TextBox1.Text)