opengl 2d转3d点
时间: 2023-09-17 18:15:03 浏览: 62
在OpenGL中,将2D点转换为3D点可以通过以下步骤实现:
1. 设置投影矩阵为透视投影矩阵。这可以通过使用gluPerspective函数来完成,该函数需要指定视野角度、屏幕宽高比、近剪切面和远剪切面。
2. 在2D屏幕坐标系中,将点的Z坐标设置为0。
3. 使用gluUnProject函数将2D点转换为3D点。该函数需要指定2D点的坐标、深度值和视图矩阵。
4. 将3D点与观察点和目标点之间的线段相交。这可以通过使用gluUnProject函数来完成,该函数需要指定观察点和目标点的坐标和视图矩阵。
以下是一个OpenGL转换2D点为3D点的示例代码:
```c++
// 2D point coordinates
float x = 100;
float y = 200;
// Depth value of the point
float depth = 0;
// Viewport dimensions
int viewport[4] = {0, 0, screenWidth, screenHeight};
// Modelview matrix
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Projection matrix
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0, (float)screenWidth / (float)screenHeight, 0.1, 100.0);
// Convert 2D point to 3D point
GLdouble point3D_x, point3D_y, point3D_z;
gluUnProject(x, screenHeight - y, depth, modelviewMatrix, projectionMatrix, viewport, &point3D_x, &point3D_y, &point3D_z);
// Calculate intersection point with the line between the eye and target
GLdouble eye_x = 0, eye_y = 0, eye_z = 0;
GLdouble target_x = 0, target_y = 0, target_z = -1;
GLdouble intersection_x, intersection_y, intersection_z;
gluUnProject(x, screenHeight - y, 1.0, modelviewMatrix, projectionMatrix, viewport, &intersection_x, &intersection_y, &intersection_z);
gluUnProject(x, screenHeight - y, 0.0, modelviewMatrix, projectionMatrix, viewport, &eye_x, &eye_y, &eye_z);
GLdouble line_x = intersection_x - eye_x;
GLdouble line_y = intersection_y - eye_y;
GLdouble line_z = intersection_z - eye_z;
GLdouble t = -eye_z / line_z;
point3D_x = eye_x + t * line_x;
point3D_y = eye_y + t * line_y;
point3D_z = eye_z + t * line_z;
```