关于c ++：需要帮助在OpenGL中移动相机

need help moving a camera in OpenGL

我正在开发一个简单的OpenGL项目。我想让一个简单的相机在透视模式下移动。

我一直在读投影矩阵、GluLook和模型视图矩阵。我一直在读，我所要做的就是在投影矩阵中调用透视图，然后在模型视图矩阵中调用所有转换和相机移动。

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#include"GLheaders.h"

void drawWorldAxis() {
glLoadIdentity();
glBegin(GL_LINES);
glNormal3f(0, 0, 1);
glColor3ub(255, 0, 0);
glVertex3f(0,0,0);
glVertex3f(1,0,0);
glColor3ub(0, 255, 0);
glVertex3f(0,0,0);
glVertex3f(0,1,0);
glColor3ub(0, 0, 255);
glVertex3f(0,0,0);
glVertex3f(0,0,1);
glEnd();
}

void keyboard(unsigned char key, int x, int y) {
glutPostRedisplay();
}

static float eye[3] = {.5, .5, .5};
#include <stdio.h>
void display() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(55.0, 1, .1, 10000);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
drawWorldAxis();
printf("eye at <%f, %f, %f>
", eye[0], eye[1], eye[2]);
fflush(stdout);
gluLookAt(eye[0], eye[1], eye[2], 0, 0, 0, 0, 1, 0);

eye[0] += .1;
eye[1] += .1;

glFlush();
glutSwapBuffers();
}

void reshape(int w, int h) {
glViewport(0,0,w,h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(55.0, 1, -1, 10000);
glMatrixMode(GL_MODELVIEW);
glutPostRedisplay();

}

int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE| GLUT_DEPTH);
glutInitWindowSize(400,400);
glutCreateWindow("Tiny Test");

glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);

glEnable(GL_NORMALIZE);
glEnable(GL_DEPTH_TEST);

glutMainLoop();

return EXIT_SUCCESS;
}

我希望这段代码显示三行代表世界坐标系的X、Y和Z轴，当按下键时，相机应该移动并开始从越来越大的角度查看原点/坐标轴。

这里出什么事了？我把脑袋撞到墙上，想弄明白为什么没有东西动。只有当我把glulookat调用放在投影矩阵中，它才会改变，我一直被告知这是一个糟糕的主意。

坐标十字是在设置注视矩阵之前绘制的，因此该矩阵不起作用。

您必须更改顺序，以便在绘制时矩阵已经存在：

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glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(eye[0], eye[1], eye[2], 0, 0, 0, 0, 1, 0);
drawWorldAxis();
printf("eye at <%f, %f, %f>
", eye[0], eye[1], eye[2]);
fflush(stdout);

然后还有第二个问题：您正在重置drawWorldAxis的第一行中的模型矩阵。在这里，您可以删除glLoadIdentity调用，或者先将前一个矩阵推送到堆栈中：

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glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(eye[0], eye[1], eye[2], 0, 0, 0, 0, 1, 0);

glPushMatrix();

drawWorldAxis();

glPopMatrix();

printf("eye at <%f, %f, %f>
", eye[0], eye[1], eye[2]);
fflush(stdout);

相关讨论

感谢@bdl帮助解决此问题！这是我想要的正确代码

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#include"GLheaders.h"

void drawWorldAxis() {
glBegin(GL_LINES);
glNormal3f(0, 0, 1);
glColor3ub(255, 0, 0);
glVertex3f(0,0,0);
glVertex3f(1,0,0);
glColor3ub(0, 255, 0);
glVertex3f(0,0,0);
glVertex3f(0,1,0);
glColor3ub(0, 0, 255);
glVertex3f(0,0,0);
glVertex3f(0,0,1);
glEnd();
}

void keyboard(unsigned char key, int x, int y) {
glutPostRedisplay();
}

static float eye[3] = {-.1, -.1, 1};
#include <stdio.h>
void display() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(55.0, 1, .1, 10000);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
printf("eye at <%f, %f, %f>
", eye[0], eye[1], eye[2]);
fflush(stdout);
gluLookAt(eye[0], eye[1], eye[2], 0, 0, 0, 0, 1, 0);
drawWorldAxis();

eye[0] += .1;
eye[1] += .1;

glFlush();
glutSwapBuffers();
}

void reshape(int w, int h) {
glViewport(0,0,w,h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(55.0, 1, -1, 10000);
glMatrixMode(GL_MODELVIEW);
glutPostRedisplay();

}

int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE| GLUT_DEPTH);
glutInitWindowSize(400,400);
glutCreateWindow("Tiny Test");

glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);

glEnable(GL_NORMALIZE);
glEnable(GL_DEPTH_TEST);

glutMainLoop();

return EXIT_SUCCESS;
}