绘制大脑表层并高亮染色的工作是以openGL加载obj文件为基础的，这里是我们用到的原始程序：只能加载一个obj文件的demo。
然而，一个完整的大脑表层是由很多分区组成的，因此我们的程序需要支持两个功能：
- 同时加载多个obj文件。
- 每个大脑分区obj文件保持其相对位置。
明白了需求后，我们就可以开始修改代码了~
glmUnitize函数的作用是单位化，也就是把模型通过平移和缩放变换限制到3维坐标系中点为中心的一个单位正方体区域内。所以控制obj显示位置是在glmUnitize()函数中，源代码如下：
1 /* public functions */
2
3 /* glmUnitize: "unitize" a model by translating it to the origin and
4 * scaling it to fit in a unit cube around the origin. Returns the
5 * scalefactor used.
6 *
7 * model - properly initialized GLMmodel structure
8 */
9 GLfloat
10 glmUnitize(GLMmodel* model, GLfloat center[3])
11 {
12 GLuint i;
13 GLfloat maxx, minx, maxy, miny, maxz, minz;
14 GLfloat cx, cy, cz, w, h, d;
15 GLfloat scale;
16
17 assert(model);
18 assert(model->vertices);
19
20 /* get the max/mins */
21 maxx = minx = model->vertices[3 + X];
22 maxy = miny = model->vertices[3 + Y];
23 maxz = minz = model->vertices[3 + Z];
24 for (i = 1; i <= model->numvertices; i++) {
25 if (maxx < model->vertices[3 * i + X])
26 maxx = model->vertices[3 * i + X];
27 if (minx > model->vertices[3 * i + X])
28 minx = model->vertices[3 * i + X];
29
30 if (maxy < model->vertices[3 * i + Y])
31 maxy = model->vertices[3 * i + Y];
32 if (miny > model->vertices[3 * i + Y])
33 miny = model->vertices[3 * i + Y];
34
35 if (maxz < model->vertices[3 * i + Z])
36 maxz = model->vertices[3 * i + Z];
37 if (minz > model->vertices[3 * i + Z])
38 minz = model->vertices[3 * i + Z];
39 }
40
41 /* calculate model width, height, and depth */
42 w = _glmAbs(maxx) + _glmAbs(minx);
43 h = _glmAbs(maxy) + _glmAbs(miny);
44 d = _glmAbs(maxz) + _glmAbs(minz);
45
46 /* calculate center of the model */
47 cx = (maxx + minx) / 2.0;
48 cy = (maxy + miny) / 2.0;
49 cz = (maxz + minz) / 2.0;
50
51 /* calculate unitizing scale factor */
52 scale = 2.0 / _glmMax(_glmMax(w, h), d);
53
54 /* translate around center then scale */
55 for (i = 1; i <= model->numvertices; i++) {
56 model->vertices[3 * i + X] -= cx;
57 model->vertices[3 * i + Y] -= cy;
58 model->vertices[3 * i + Z] -= cz;
59 model->vertices[3 * i + X] *= scale;
60 model->vertices[3 * i + Y] *= scale;
61 model->vertices[3 * i + Z] *= scale;
62 }
63
64 center[0] = cx;
65 center[1] = cy;
66 center[2] = cz;
67 return scale;
68 }
glmUnitize
这里我们要修改两个内容：
- 删除改变位置的代码
- 改变缩放比例，各个obj文件的缩放因子需要保持一致。
这是修改后的代码：
1 /* public functions */
2
3 /* glmUnitize: "unitize" a model by translating it to the origin and
4 * scaling it to fit in a unit cube around the origin. Returns the
5 * scalefactor used.
6 *
7 * model - properly initialized GLMmodel structure
8 */
9 GLfloat
10 glmUnitize(GLMmodel* model, GLfloat center[3])
11 {
12 GLuint i;
13 GLfloat maxx, minx, maxy, miny, maxz, minz;
14 GLfloat cx, cy, cz, w, h, d;
15 GLfloat scale;
16
17 assert(model);
18 assert(model->vertices);
19
20 /* get the max/mins */
21 maxx = minx = model->vertices[3 + X];
22 maxy = miny = model->vertices[3 + Y];
23 maxz = minz = model->vertices[3 + Z];
24 for (i = 1; i <= model->numvertices; i++) {
25 if (maxx < model->vertices[3 * i + X])
26 maxx = model->vertices[3 * i + X];
27 if (minx > model->vertices[3 * i + X])
28 minx = model->vertices[3 * i + X];
29
30 if (maxy < model->vertices[3 * i + Y])
31 maxy = model->vertices[3 * i + Y];
32 if (miny > model->vertices[3 * i + Y])
33 miny = model->vertices[3 * i + Y];
34
35 if (maxz < model->vertices[3 * i + Z])
36 maxz = model->vertices[3 * i + Z];
37 if (minz > model->vertices[3 * i + Z])
38 minz = model->vertices[3 * i + Z];
39 }
40
41 /* calculate model width, height, and depth */
42 w = _glmAbs(maxx) + _glmAbs(minx);
43 h = _glmAbs(maxy) + _glmAbs(miny);
44 d = _glmAbs(maxz) + _glmAbs(minz);
45
46 /* calculate center of the model */
47 cx = (maxx + minx) / 2.0;
48 cy = (maxy + miny) / 2.0;
49 cz = (maxz + minz) / 2.0;
50
51 /* calculate unitizing scale factor */
52 //scale = 2.0 / _glmMax(_glmMax(w, h), d);
53 scale = 0.01;
54 /* translate around center then scale */
55 for (i = 1; i <= model->numvertices; i++) {
56 /* model->vertices[3 * i + X] -= cx;
57 model->vertices[3 * i + Y] -= cy;
58 model->vertices[3 * i + Z] -= cz;*/
59 model->vertices[3 * i + X] *= scale;
60 model->vertices[3 * i + Y] *= scale;
61 model->vertices[3 * i + Z] *= scale;
62 }
63
64 center[0] = cx;
65 center[1] = cy;
66 center[2] = cz;
67 return scale;
68 }
现在我们要解决同时加载多个obj文件的问题。
- pModel改为pModel数组，全局变量cnt记录当前加载到哪个obj文件。
- 遍历obj文件夹下的所有obj文件，并依次加载。
核心代码如下：
1 case ‘o‘:
2 case ‘O‘:
3 {
4 string path="C:\\test";
5 _finddata_t file_info;
6 string current_path = path + "/*.obj";
7 int handle = _findfirst(current_path.c_str(), &file_info);
8 do
9 {
10
11 string rt = "C:\\test\\";
12 string fn= rt + file_info.name;
13 memset(FileName, ‘\0‘, sizeof(FileName));
14 for (int i = 0; i < fn.length(); i++)
15 {
16 FileName[i] = fn[i];
17 }
18 if (pModel[cnt] == NULL)
19 {
20 pModel[cnt] = glmReadOBJ(FileName);
21 // Generate normal for the model
22 glmFacetNormals(pModel[cnt]);
23 // Scale the model to fit the screen
24 glmUnitize(pModel[cnt], modelCenter);
25 // Init the modelview matrix as an identity matrix
26 glMatrixMode(GL_MODELVIEW);
27 glLoadIdentity();
28 glGetDoublev(GL_MODELVIEW_MATRIX, pModelViewMatrix);
29 cnt++;
30 // break;
31 }
32
33 } while (!_findnext(handle, &file_info));
34
35 _findclose(handle);
36 }
37
38 break;
1 void display()
2 {
3 glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
4 glMatrixMode(GL_MODELVIEW);
5 glLoadIdentity();
6 glTranslated( 0.0, 0.0, -5.0 );
7 glMultMatrixd( pModelViewMatrix );
8 for (int i = 0; i < cnt; i++)
9 {
10 if (pModel[i] != NULL)
11 {
12 glmDraw(pModel[i], GLM_FLAT);
13 }
14 }
15 glutSwapBuffers();
16 }
Display
现在我们要给加载的多个obj文件随机染色。
1 void Color()
2 {
3 srand(unsigned(time(0)));
4 for (int i = 0; i < maxn; i++)
5 {
6
7 rr[i] = random(0.0, 0.7);
8 gg[i] = random(0.0, 0.7);
9 bb[i] = random(0.0, 0.7);
10 cout << rr[i] << " " << gg[i] << " " << bb[i] << endl;
11 }
12 }
1 /// Display the Object
2 void display()
3 {
4 glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
5
6 glMatrixMode(GL_MODELVIEW);
7 glLoadIdentity();
8
9 glTranslated( 0.0, 0.0, -5.0 );
10 glMultMatrixd( pModelViewMatrix );
11
12 glEnable(GL_COLOR_MATERIAL);
13 //glColorMaterial(GL_FRONT, GL_DIFFUSE);
14
15 for (int i = 0; i < cnt; i++)
16 {
17 if (pModel[i] != NULL)
18 {
19 glColor3f(rr[i],gg[i],bb[i]);
20 glmDraw(pModel[i], GLM_FLAT|GLM_COLOR);
21 }
22 }
23 glDisable(GL_COLOR_MATERIAL);
24 glutSwapBuffers();
25 }
到此为止吗，我们就完成了openGL加载obj文件+绘制大脑表层+高亮染色。点击下载：openGLhighlight.zip
时间： 2024-08-06 07:54:18