我正在尝试制作一个程序，可以放大和缩小我绘制的图形，但没有这样做；它会切换图形的方向，如果我继续滚动，它就会消失。假定要执行的功能是MouseFunc()和renderScene()。欢迎对问题或帮助进行任何解释。
#include"glut.h"
#include<cmath>
#include<iostream>
using namespace std;
float xr = 0, yr = 0; //to control the object's movement from left to right
// XZ position of the camera
float x = 0.0f, z = 5.0f; //Module 4
float angleX = 0.0f; //Module 4
//Shift + ArrowKey rotation
float transX = 0.0f;
float transY = 0.0f;
float rotY = 0.0f;
//end
//Mouse Commands
//float ZoomFactor = 0.5;
GLfloat theta3 = 0;
GLfloat phi = 0;
GLfloat rho = 5;
GLfloat camX = 0;
GLfloat camY = 0;
GLfloat camZ = 0;
GLfloat upX = 0;
GLfloat upY = 0;
GLfloat upZ = 0;
//end
GLfloat angle = 0.0f;
int refreshmill = 1;
void timer(int value) { //to control the rotation of the object
glutTimerFunc(refreshmill, timer, 0);
}
void myDisplay(void) {
//Circle One
float theta;
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1, 0, 0);
glPushMatrix();
glBegin(GL_POLYGON);
for (int x = 0; x < 360; x++) {
theta = x * 3.142 / 180;
glVertex2f(150 * cos(theta) + xr, 150 * sin(theta) + yr);
}
glEnd();
glPopMatrix();
//Circle Two
float theta2;
glPushMatrix();
glTranslatef(0.5f, 0.0f, 0.0f); // rotation
glRotatef(angle, 0.0f, 0.0f, -0.5f); // rotation
glBegin(GL_POLYGON);
glColor3f(0, 0, 1);
for (int x = 0; x < 360; x++) {
theta2 = x * 3.142 / 180;
glVertex2f(150 + 15 * cos(theta2) + xr, 15 * sin(theta2) + yr);
}
angle += 0.2; // rotation
glEnd();
glPopMatrix();
//Draw Star
glColor3ub(119, 193, 15);
glPushMatrix();
glBegin(GL_POLYGON);
glVertex2d(15 + xr, 60 + yr);
glVertex2d(75 + xr, 75 + yr); //right peak
glVertex2d(15 + xr, 90 + yr);
glVertex2d(0 + xr, 150 + yr); //Up-peak Changed
glVertex2d(-15 + xr, 90 + yr);
glVertex2d(-75 + xr, 75 + yr);
glVertex2d(-15 + xr, 60 + yr);
glVertex2d(0 + xr, 0 + yr);
glEnd();
glPopMatrix();
}
//Close code
void handleKeypress(unsigned char key, int x, int y){
switch (key){
case 27: //when the escape key is pressed the program will exit.
exit(0);
}
}
//Movement of drawing
void keyboard(int key, int x, int y) {
float fraction = 0.1f;
bool shift = false;
int mod = glutGetModifiers();
if (mod == GLUT_ACTIVE_SHIFT) {
shift = true;
}
if (!shift) {
switch (key) {
case GLUT_KEY_RIGHT: xr++; break;
case GLUT_KEY_LEFT: xr--; break;
case GLUT_KEY_UP: angleX -= 1.0f; break; //Module 4
case GLUT_KEY_DOWN: angleX += 1.0f; break; //Module 4
}
}
else {
switch (key) {
case GLUT_KEY_LEFT:// Rotación del dibujo hacia la izquierda en el eje de Y
rotY -= 1.0f;
break;
case GLUT_KEY_RIGHT:// Rotación del dibujo hacia la derecha en el eje de Y
rotY += 1.0f;
break;
}
}
}
//Mouse Function
void MouseFunc(int button, int state, int x, int y){
if (button > 4){
rho = rho + 3.0;
}
else (button < 3);{
rho = rho - 3.0;
}
}
void renderScene(void) {
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(0.0, 1.0, 0.0);
glRotatef(rotY, 0.0, 1.0, 0.0); //Rotation with Shift + ArrowKey
GLfloat camX = rho * cos(theta3*3.1415926f / 180)*sin(phi*3.1415926f / 180);
GLfloat camY = rho * sin(theta3*3.1415926f / 180);
GLfloat camZ = rho * cos(theta3*3.1415926f / 180)*cos(phi*3.1415926f / 180);
// Reduce theta slightly to obtain another point on the same longitude line on the sphere.
GLfloat dt = 1;
GLfloat eyeXtemp = -rho * cos((theta3 - dt)*3.1415926f / 180)*sin(phi*3.1415926f / 180);
GLfloat eyeYtemp = -rho * sin((theta3 - dt)*3.1415926f / 180);
GLfloat eyeZtemp = -rho * cos((theta3 - dt)*3.1415926f / 180)*cos(phi*3.1415926f / 180);
// Connect these two points to obtain the camera's up vector.
GLfloat upX = eyeXtemp - camX;
GLfloat upY = eyeYtemp - camY;
GLfloat upZ = eyeZtemp - camZ;
// Clear Color and Depth Buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Reset transformations
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Set the camera
gluLookAt(camX, camY, camZ, 0, 0, 0, upX, upY, upZ);
gluLookAt(x, 0.0f, z, x, 0.0f, z - 1.0f, 0.0f, 1.0f, 0.0f); //Module 4
glRotatef(angleX, 1, 0, 0); //Module 4
myDisplay();
glFlush();
glutPostRedisplay();
glutSwapBuffers();
}
void init() {
glClearColor(0, 0, 0, 1);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(0.0f, 0.1f, 0.1f, 0.0f);
glOrtho(-250, 250, -250, 250, -250, 250); //IMPORTANT- Define from negative to positive
glMatrixMode(GL_MODELVIEW);
}
int main(int argc, char** argv) {
// init GLUT and create window
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(500, 500);
glutInitWindowPosition(0, 0);
glutCreateWindow("Homework: Circle");
// register callbacks
glutDisplayFunc(renderScene);
glutTimerFunc(0,timer,0);
glutKeyboardFunc(handleKeypress);
glutSpecialFunc(keyboard);
glutMouseFunc(MouseFunc);
// OpenGL init
init();
// enter GLUT event processing cycle
glutMainLoop();
}
最佳答案
连接以设置透 View 和正投影。删除透视投影gluPerspective:
void init() {
glClearColor(0, 0, 0, 1);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//gluPerspective(0.0f, 0.1f, 0.1f, 0.0f); <---- delete
glOrtho(-250, 250, -250, 250, -250, 250);
glMatrixMode(GL_MODELVIEW);
}
如果要缩放，则必须更改正投影(
glOrtho )。投影矩阵描述了从场景的3D点到视口(viewport)的2D点的映射。实现鼠标滚轮事件，该事件将在限定范围内更改
zoom:例如
GLdouble zoom = 0.0f;
void MouseFunc(int button, int state, int x, int y){
GLdouble min_z = -100.0;
GLdouble max_z = 100.0;
if (button == 4 && zoom < max_z) {
zoom += 3.0;
}
else if (button == 3 && zoom > min_z) {
zoom -= 3.0;
}
}
根据显示循环
zoom中的renderScene修改正交投影:void renderScene(void) {
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
GLdouble ortho = 250 + zoom;
glOrtho(-ortho, ortho, -ortho, ortho, -250, 250);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// [...]
}
关于c++ - 如何使用鼠标滚轮固定放大和缩小？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/55962362/