- 画图形，定义模式为GL_SELECT，并为图形创建名字堆栈：
1 /// <summary>
2 /// Draws the rectangles.
3 /// </summary>
4 /// <param name="mode">The selection mode.</param>
5 private static void DrawRects(uint mode)
6 {
7 // The three rectangles are drawn. In selection mode, each rectangle is given
8 // the same name. Note that each rectangle is drawn with a different z value.
9 if (mode == GL_SELECT)
10 {
11 glLoadName(1);
12 }
13 glBegin(GL_QUADS);
14 glColor3f(1.0f, 1.0f, 0.0f);
15 glVertex3i(2, 0, 0);
16 glVertex3i(2, 6, 0);
17 glVertex3i(6, 6, 0);
18 glVertex3i(6, 0, 0);
19 glEnd();
20
21 if (mode == GL_SELECT)
22 {
23 glLoadName(2);
24 }
25 glBegin(GL_QUADS);
26 glColor3f(0.0f, 1.0f, 1.0f);
27 glVertex3i(3, 2, -1);
28 glVertex3i(3, 8, -1);
29 glVertex3i(8, 8, -1);
30 glVertex3i(8, 2, -1);
31 glEnd();
32
33 if (mode == GL_SELECT)
34 {
35 glLoadName(3);
36 }
37 glBegin(GL_QUADS);
38 glColor3f(1.0f, 0.0f, 1.0f);
39 glVertex3i(0, 2, -2);
40 glVertex3i(0, 7, -2);
41 glVertex3i(5, 7, -2);
42 glVertex3i(5, 2, -2);
43 glEnd();
44 }
1 /// <summary>
2 /// Updates pick selection.
3 /// </summary>
4 private static void PickRects()
5 {
6 private const int BUFSIZE = 512; // sets up selection mode, name stack, and projection matrix for picking. Then the objects are drawn
7 uint[] selectBuf = new uint[BUFSIZE];
8 int hits;
9 int[] viewport = new int[4];
10
11 glGetIntegerv(GL_VIEWPORT, viewport);
12
13 glSelectBuffer(BUFSIZE, selectBuf);
14 glRenderMode(GL_SELECT);
15
16 glInitNames();
17 glPushName(0);
18
19 glMatrixMode(GL_PROJECTION);
20 glPushMatrix();
21 glLoadIdentity();
22 // create 5x5 pixel picking region near cursor location
23 gluPickMatrix((double)Model.Mouse.X, (double)(viewport[3] - Model.Mouse.Y), 5.0, 5.0, viewport);
24 glOrtho(0.0f, 8.0f, 0.0f, 8.0f, -0.5f, 2.5f);
25 DrawRects(GL_SELECT);
26 glPopMatrix();
27 glFlush();
28
29 hits = glRenderMode(GL_RENDER);
30 ProcessHits(hits, selectBuf);
31 }
32 /// <summary>
33 /// Displays hit data.
34 /// </summary>
35 /// <param name="hits">Number of hits.</param>
36 /// <param name="buffer">The selection buffer.</param>
37 private static void ProcessHits(int hits, uint[] buffer)
38 {
39 uint i, j;
40 uint names;
41 uint[] ptr;
42
43 Console.WriteLine("hits = {0}", hits);
44 ptr = buffer;
45 for (i = 0; i < hits; i++)
46 { // For Each Hit
47 names = ptr[i];
48 Console.WriteLine(" number of names for hit = {0}", names);
49 i++;
50 Console.WriteLine(" z1 is {0}", (float)ptr[i] / 0x7fffffff);
51 i++;
52 Console.WriteLine(" z2 is {0}", (float)ptr[i] / 0x7fffffff);
53 i++;
54 Console.Write(" the name is ");
55 for (j = 0; j < names; j++)
56 { // For Each Name
57 Console.Write("{0} ", ptr[i]);
58 i++;
59 }
60 Console.Write("
");
61 }
62 Console.Write("
");
63 }