opengl 放大镜

Exercise 6：放大镜功能

要求：

1. 在练习5的基础上，实现放大镜功能，放大场景中的任意部分；
2. 放大镜可以通过鼠标键盘进行控制；

考察目的：

1. 对OpenGL坐标系变换的理解；

 

我的思路就是，获取屏幕坐标，转换成opengl 坐标。移动glulookat到相应的位置，然后拉近摄像头距离，实现放大

不过，不能是正交投影，正交投影下，照相机远近不能影响大小。

特别坑爹，感觉肯定有其他方法实现。

 

屏幕坐标的转换，参考http://nehe.gamedev.net/article/using_gluunproject/16013/

pos就是转换后的结果

 1 void GLPOS(int x,int y,GLdouble pos[3])

 2 {

 3     GLint viewport[4];

 4     GLdouble modelview[16];

 5     GLdouble projection[16];

 6     GLfloat winX,winY,winZ;

 7 

 8     glGetDoublev(GL_MODELVIEW_MATRIX,modelview);

 9     glGetDoublev(GL_PROJECTION_MATRIX,projection);

10     glGetIntegerv(GL_VIEWPORT,viewport);

11 

12     winX = (float)x;

13     winY = viewport[3]-(float)y;

14     glReadPixels((int)x,(int)y,1,1,GL_DEPTH_COMPONENT,GL_FLOAT,&winZ);

15     gluUnProject(winX,winY,winZ,modelview,projection,viewport,&pos[0],&pos[1],&pos[2]);

16 }

本来是想画一个  小的十字 去跟踪鼠标。

结果，透视投影下面，用上面坐标转换的方法，跟踪鼠标，因为是视景体是梯形，所以效果不好

正交投影下，十字可以跟着鼠标走，但是又没办法放大了。

全部代码如下：

  1 #include <windows.h>

  2 #include <GL/glut.h>

  3 #include <GL/glext.h>

  4 #include <GL/SOIL.h>

  5 #include <cstdio>

  6 

  7 /* 正方体旋转*/

  8 GLfloat xrot1 = 0.0f;

  9 GLfloat yrot1 = 0.0f;

 10 GLfloat xrot2 = 0.0f;

 11 GLfloat yrot2 = 0.0f;

 12 GLfloat xrot3 = 0.0f;

 13 GLfloat yrot3 = 0.0f;

 14 GLfloat xrot4 = 0.0f;

 15 GLfloat yrot4 = 0.0f;

 16 /*旋转速度*/

 17 GLfloat xspeed = 5.0f;

 18 GLfloat yspeed = 5.0f;

 19 /*放大相关*/

 20 GLdouble eyex = 0.0f;

 21 GLdouble eyey = 0.0f;

 22 GLdouble centerx = 0.0f;

 23 GLdouble centery = 0.0f;

 24 

 25 GLdouble eyez = 15.0f;//放大镜值

 26 /*焦点*/

 27 GLfloat focusx = 0.0f;

 28 GLfloat focusy = 0.0f;

 29 GLfloat focusz = 15.0f;

 30 

 31 GLuint texture[1];

 32 

 33 int loadGLTextures()

 34 {

 35     for(int i=0; i<3; i++)

 36     {

 37         texture[i] = SOIL_load_OGL_texture

 38                      (

 39                          "F://LI//opengl-test//practice_big//Crate.bmp",

 40                          SOIL_LOAD_AUTO,

 41                          SOIL_CREATE_NEW_ID,

 42                          SOIL_FLAG_INVERT_Y

 43                      );

 44     }

 45 

 46     if(texture[0] == 0)

 47     {

 48         printf("load  error");

 49         return 0;

 50     }

 51     glBindTexture(GL_TEXTURE_2D, texture[0]);

 52     glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);

 53     glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);

 54     glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_REPEAT);

 55     glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_REPEAT);

 56 

 57     return true;

 58 }

 59 

 60 void  init ()

 61 {

 62     loadGLTextures();

 63     glEnable(GL_TEXTURE_2D);

 64     glShadeModel(GL_SMOOTH);

 65     glClearColor(0.0,0.0,0.0,0.0);

 66     glClearDepth(1.0);

 67     glEnable(GL_DEPTH_TEST);

 68     glDepthFunc(GL_LEQUAL);

 69     glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST);

 70 }

 71 void reshape(int w,int h)

 72 {

 73     glViewport(0,0,(GLsizei)w,(GLsizei)h);

 74     glMatrixMode(GL_PROJECTION);

 75     glLoadIdentity();

 76     gluPerspective(45.0,(GLfloat)w/(GLfloat)h,0.1,100.0);

 77    // glOrtho(-10.0f,10.0f,-10.0f*(GLfloat)h/(GLfloat)w,10.0f*(GLfloat)h/(GLfloat)w,0.1,100.0);

 78     glMatrixMode(GL_MODELVIEW);

 79 }

 80 void drawQuads(GLfloat xrot,GLfloat yrot)

 81 {

 82     glTranslatef(0.0f,0.0f,0.0f);

 83     glRotatef(xrot1,1.0f,0.0f,0.0f);

 84     glRotatef(yrot1,0.0f,1.0f,0.0f);

 85     glBindTexture(GL_TEXTURE_2D,texture[0]);

 86     glBegin(GL_QUADS);

 87     // 前侧面

 88     glNormal3f( 0.0f, 0.0f, 1.0f);                    // 法线指向观察者

 89     glTexCoord2f(0.0f, 0.0f);glVertex3f(-1.0f, -1.0f,  1.0f);

 90     glTexCoord2f(1.0f, 0.0f);glVertex3f( 1.0f, -1.0f,  1.0f);

 91     glTexCoord2f(1.0f, 1.0f);glVertex3f( 1.0f,  1.0f,  1.0f);

 92     glTexCoord2f(0.0f, 1.0f);glVertex3f(-1.0f,  1.0f,  1.0f);

 93     // 后侧面

 94     glNormal3f( 0.0f, 0.0f,-1.0f);                    // 法线背向观察者

 95     glTexCoord2f(1.0f, 0.0f);

 96     glVertex3f(-1.0f, -1.0f, -1.0f);

 97     glTexCoord2f(1.0f, 1.0f);

 98     glVertex3f(-1.0f,  1.0f, -1.0f);

 99     glTexCoord2f(0.0f, 1.0f);

100     glVertex3f( 1.0f,  1.0f, -1.0f);

101     glTexCoord2f(0.0f, 0.0f);

102     glVertex3f( 1.0f, -1.0f, -1.0f);

103     // 顶面

104     glNormal3f( 0.0f, 1.0f, 0.0f);                    // 法线向上

105     glTexCoord2f(0.0f, 1.0f);

106     glVertex3f(-1.0f,  1.0f, -1.0f);

107     glTexCoord2f(0.0f, 0.0f);

108     glVertex3f(-1.0f,  1.0f,  1.0f);

109     glTexCoord2f(1.0f, 0.0f);

110     glVertex3f( 1.0f,  1.0f,  1.0f);

111     glTexCoord2f(1.0f, 1.0f);

112     glVertex3f( 1.0f,  1.0f, -1.0f);

113     // 底面

114     glNormal3f( 0.0f,-1.0f, 0.0f);                    // 法线朝下

115     glTexCoord2f(1.0f, 1.0f);

116     glVertex3f(-1.0f, -1.0f, -1.0f);

117     glTexCoord2f(0.0f, 1.0f);

118     glVertex3f( 1.0f, -1.0f, -1.0f);

119     glTexCoord2f(0.0f, 0.0f);

120     glVertex3f( 1.0f, -1.0f,  1.0f);

121     glTexCoord2f(1.0f, 0.0f);

122     glVertex3f(-1.0f, -1.0f,  1.0f);

123     // 右侧面

124     glNormal3f( 1.0f, 0.0f, 0.0f);                    // 法线朝右

125     glTexCoord2f(1.0f, 0.0f);

126     glVertex3f( 1.0f, -1.0f, -1.0f);

127     glTexCoord2f(1.0f, 1.0f);

128     glVertex3f( 1.0f,  1.0f, -1.0f);

129     glTexCoord2f(0.0f, 1.0f);

130     glVertex3f( 1.0f,  1.0f,  1.0f);

131     glTexCoord2f(0.0f, 0.0f);

132     glVertex3f( 1.0f, -1.0f,  1.0f);

133     // 左侧面

134     glNormal3f(-1.0f, 0.0f, 0.0f);                    // 法线朝左

135     glTexCoord2f(0.0f, 0.0f);

136     glVertex3f(-1.0f, -1.0f, -1.0f);

137     glTexCoord2f(1.0f, 0.0f);

138     glVertex3f(-1.0f, -1.0f,  1.0f);

139     glTexCoord2f(1.0f, 1.0f);

140     glVertex3f(-1.0f,  1.0f,  1.0f);

141     glTexCoord2f(0.0f, 1.0f);

142     glVertex3f(-1.0f,  1.0f, -1.0f);

143     glEnd();

144 

145 }

146 

147 void drawFocus()

148 {

149     GLfloat a = 1.0f;

150     glColor3f(1.0f,1.0f,1.0f);

151     glLineWidth(1.0f);

152     glBegin(GL_LINES);

153         glVertex3f(-1.0f/a,1.0f/a,0.0f);

154         glVertex3f(-1.0f/a,3.0f/a,0.0f);

155     glEnd();

156     glBegin(GL_LINES);

157         glVertex3f(-1.0f/a,1.0f/a,0.0f);

158         glVertex3f(-3.0f/a,1.0f/a,0.0f);

159     glEnd();

160     glBegin(GL_LINES);

161         glVertex3f(1.0f/a,1.0f/a,0.0f);

162         glVertex3f(1.0f/a,3.0f/a,0.0f);

163     glEnd();

164     glBegin(GL_LINES);

165         glVertex3f(1.0f/a,1.0f/a,0.0f);

166         glVertex3f(3.0f/a,1.0f/a,0.0f);

167     glEnd();

168     glBegin(GL_LINES);

169         glVertex3f(-1.0f/a,-1.0f/a,0.0f);

170         glVertex3f(-1.0f/a,-3.0f/a,0.0f);

171     glEnd();

172     glBegin(GL_LINES);

173         glVertex3f(-1.0f/a,-1.0f/a,0.0f);

174         glVertex3f(-3.0f/a,-1.0f/a,0.0f);

175     glEnd();

176 

177     glBegin(GL_LINES);

178         glVertex3f(1.0f/a,-1.0f/a,0.0f);

179         glVertex3f(1.0f/a,-3.0f/a,0.0f);

180     glEnd();

181     glBegin(GL_LINES);

182         glVertex3f(1.0f/a,-1.0f/a,0.0f);

183         glVertex3f(3.0f/a,-1.0f/a,0.0f);

184     glEnd();

185 }

186 

187 void display()

188 {

189     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

190     glLoadIdentity();

191 

192     /*glPushMatrix();

193         glDisable(GL_TEXTURE_2D);

194         glTranslatef(focusx,focusy,focusz);

195         drawFocus();

196         glEnable(GL_TEXTURE_2D);

197     glPopMatrix();*/

198 

199     gluLookAt(eyex,eyey,eyez,centerx,centery,-1.0f,0.0f,1.0f,0.0f);

200 

201     /*glPushMatrix();

202         glPointSize(5.0f);

203         glBegin(GL_POINTS);

204             glVertex3f(9.0f,0.0f,0.0f);

205         glEnd();

206     glPopMatrix();*/

207 

208     glPushMatrix();

209         glTranslatef(-3.5f,2.5f,0.0f);

210         drawQuads(xrot1,yrot1);

211     glPopMatrix();

212 

213     glPushMatrix();

214         glTranslatef(3.5f,2.5f,0.0f);

215         drawQuads(xrot2,yrot2);

216     glPopMatrix();

217 

218     glPushMatrix();

219         glTranslatef(-3.5f,-2.5f,0.0f);

220         drawQuads(xrot3,yrot3);

221     glPopMatrix();

222 

223     glPushMatrix();

224         glTranslatef(3.5f,-2.5f,0.0f);

225         drawQuads(xrot4,yrot4);

226     glPopMatrix();

227 

228     glFlush();

229 

230 }

231 

232 void GLPOS(int x,int y,GLdouble pos[3])

233 {

234     GLint viewport[4];

235     GLdouble modelview[16];

236     GLdouble projection[16];

237     GLfloat winX,winY,winZ;

238 

239     glGetDoublev(GL_MODELVIEW_MATRIX,modelview);

240     glGetDoublev(GL_PROJECTION_MATRIX,projection);

241     glGetIntegerv(GL_VIEWPORT,viewport);

242 

243     winX = (float)x;

244     winY = viewport[3]-(float)y;

245     glReadPixels((int)x,(int)y,1,1,GL_DEPTH_COMPONENT,GL_FLOAT,&winZ);

246     gluUnProject(winX,winY,winZ,modelview,projection,viewport,&pos[0],&pos[1],&pos[2]);

247 }

248 void mouse(int button,int state,int x,int y)

249 {

250 

251     switch(button)

252     {

253     case GLUT_LEFT_BUTTON:

254         if(state == GLUT_DOWN)

255         {

256             printf("%d,%d\n",x,y);

257             GLdouble *pos = new GLdouble[3];

258             GLPOS(x,y,pos);

259             printf("%f,%f,%f\n",pos[0],pos[1],pos[2]);

260             eyex = pos[0];

261             eyey = pos[1];

262             centerx = pos[0];

263             centery = pos[1];

264             glutPostRedisplay();

265         }

266         break;

267     case GLUT_RIGHT_BUTTON:

268         if(state == GLUT_DOWN)

269         {

270             eyex = 0.0f;

271             eyey = 0.0f;

272             centerx = 0.0f;

273             centery = 0.0f;

274             glutPostRedisplay();

275         }

276         break;

277     }

278 }

279 void mouse_move(int x,int y)

280 {

281     GLdouble *pos = new GLdouble[3];

282     GLPOS(x,y,pos);

283     printf("%f,%f,%f\n",pos[0],pos[1],pos[2]);

284     focusx = (GLfloat)pos[0];

285     focusy = (GLfloat)pos[1];

286     focusz = (GLfloat)pos[2];

287     delete [] pos;

288     glutPostRedisplay();

289 }

290 

291 void keyboard(unsigned char key,int x,int y)

292 {

293     switch(key)

294     {

295     case 'u':

296         eyez-=0.5f;

297         break;

298     case 'd':

299         eyez+=0.5f;

300         break;

301     case 27:

302         exit(0);

303         break;

304     }

305     glutPostRedisplay();

306 }

307 int main(int argc,char **argv)

308 {

309     glutInit(&argc,argv);

310     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);

311     glutInitWindowSize(900,600);

312     glutInitWindowPosition(400,100);

313     glutCreateWindow("hello world");

314     init();

315     glutDisplayFunc(display);

316     glutReshapeFunc(reshape);

317     glutKeyboardFunc(keyboard);

318     glutMouseFunc(mouse);

319     //glutPassiveMotionFunc(mouse_move);

320     glutMainLoop();

321     return 0;

322 }

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