OpenGL - 让相机移动

Posted 2023-02-22

【中文标题】OpenGL - 让相机移动

【英文标题】：OpenGL - Getting camera to move

【发布时间】：2018-03-15 21:54:10

【问题描述】：

我的 OpenGL 游戏出现问题，无法让相机移动。

我无法使用 GLFW、GLUT 和 glulookat()。这是我的代码，有什么问题？

P.S 一切正常，除了相机移动意味着游戏可以完美运行，只是不能移动相机。

我的相机代码：

    #include "SpriteRenderer.h"

    #include <glm/glm.hpp>
    #include <glm/gtc/matrix_transform.hpp>

    class Camera

private:
    Shader shader;

    GLfloat     angle = -90.f;

    glm::vec3   cameraFront = glm::vec3(0.0f, 0.0f, -1.0f),
                cameraPosition = glm::vec3(0.0f, 0.0f, 0.1f),
                cameraUp = glm::vec3(0.0f, 1.0f, 0.0f);

    glm::mat4   viewMatrix;

    // recompute the view matrix from the camera variables
    void updateMatrix()
    
        viewMatrix = glm::lookAt(cameraPosition, cameraPosition + cameraFront, cameraUp);
    

    // default constructor
    void defaultNew()
    
        cameraPosition = glm::vec3(0.0f, 0.0f, 0.1f);
        cameraFront = glm::vec3(0.0f, 0.0f, -1.0f);
        cameraUp = glm::vec3(0.0f, 1.0f, 0.0f);
        updateMatrix();
    

public:
    Camera()  defaultNew(); 
    Camera(Shader &shader)  this->shader = shader; defaultNew(); 

    glm::mat4 GetViewMatrix() const
    
        // if your view matrix is always up-to-date, just return it directly
        return viewMatrix;
    

    // get functions
    glm::vec3 GetCameraPosition() const  return cameraPosition; 
    // .. same for Front and Up

    // set functions
    // call updateMatrix every time you update a variable
    void SetCameraPosition(glm::vec3 pos)
    
        cameraPosition = pos;
        updateMatrix();
    
    // .. same for Front and Up

    // no need to use this-> all the time
    virtual void Draw()
    
        this->shader.Use();
        this->shader.SetMatrix4("view", viewMatrix);    
    
;

我的着色器代码：

Shader &Use() glUseProgram(this->ID); return *this; 

void SetMatrix4(const GLchar *name, const glm::mat4 &matrix, GLboolean useShader = false)
     if (useShader)this->Use(); glUniformMatrix4fv(glGetUniformLocation(this->ID, name), 1, GL_FALSE, glm::value_ptr(matrix)); 

我的游戏代码：

Camera *View;

projection2 = glm::perspective(glm::radians(44.0f), (float)this->Width / (float)this->Width, 0.1f, 100.0f);

AssetController::LoadShader("../src/Shaders/Light.vert", "../src/Shaders/Light.frag", "light");

AssetController::GetShader("light").SetMatrix4("projection", projection2);

View = new Camera(AssetController::GetShader("light"));

(...)

GLfloat velocity = playerSpeed * deltaTime;
glm::vec3 camPosition;

// Update Players Position
if (movingLeft)

    if (Player->Position.x >= 0)
    
        Player->Position.x -= velocity;
        if (Ball->Stuck)
            Ball->Position.x -= velocity;

        camPosition = View->GetCameraPosition();
        camPosition.x -= velocity / 2;
        View->SetCameraPosition(camPosition);
    

else if (movingRight)

    if (Player->Position.x <= this->Width - Player->Size.x)
    
        Player->Position.x += velocity;
        if (Ball->Stuck)
            Ball->Position.x += velocity;

        camPosition = View->GetCameraPosition();
        camPosition.x += velocity / 2;
        View->SetCameraPosition(camPosition);
    

(...)

GameOver->Draw(*Renderer);
    View->Draw();

我的着色器： .vert：

#version 440 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoord;

out vec2 TexCoord;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()

    gl_Position = projection * view * model * vec4(aPos, 1.0f);
    TexCoord = vec2(aTexCoord.x, aTexCoord.y);

.frag:

#version 440 core
out vec4 FragColor;

in vec2 TexCoord;

// texture samplers
uniform sampler2D texture1;
uniform sampler2D texture2;

void main()

    // linearly interpolate between both textures (80% container, 20% awesomeface)
    FragColor = mix(texture(texture1, TexCoord), texture(texture2, TexCoord), 0.2);

【参考方案1】：

问题是你只更新了局部位置变量cameraPosition，而不是视图矩阵，它在渲染过程中被传递给了OpenGL。

将相机变量和矩阵公开也是一个坏习惯，因为它们可能会被错误地修改或不同步（就像你正在做的那样）。相反，您可以编写一对get/set 函数：

class Camera

private:
   Shader shader;

   GLfloat     angle = -90.f;

   glm::vec3   cameraFront = glm::vec3(0.0f, 0.0f, -1.0f),
               cameraPosition = glm::vec3(0.0f, 0.0f, 0.1f),
               cameraUp = glm::vec3(0.0f, 1.0f, 0.0f);

   glm::mat4   viewMatrix;

   // recompute the view matrix from the camera variables
   void updateMatrix()
   
      viewMatrix = glm::lookAt(cameraPosition, cameraPosition + cameraFront, cameraUp);
   

   // default constructor
   void defaultNew()
   
      cameraPosition = glm::vec3(0.0f, 0.0f,  0.1f);
      cameraFront    = glm::vec3(0.0f, 0.0f, -1.0f);
      cameraUp       = glm::vec3(0.0f, 1.0f,  0.0f);
      updateMatrix();
   

public:
   Camera()  
      defaultNew();
   
   Camera(Shader &shader)  
      this->shader = shader;
      defaultNew();  
   

   glm::mat4 GetViewMatrix() const
   
      // if your view matrix is always up-to-date, just return it directly
      return viewMatrix;
   

   // get functions
   glm::vec3 GetCameraPosition() const  return cameraPosition; 
   // .. same for Front and Up

   // set functions
   // call updateMatrix every time you update a variable
   void SetCameraPosition(glm::vec3 p)
   
      cameraPosition = p;
      updateMatrix();
   
   // .. same for Front and Up

   // no need to use this-> all the time
   virtual void Draw()
   
      shader.Use();
      shader.SetMatrix4("view", viewMatrix);
   
;

然后当您更新相机位置时，只需使用这些函数而不是暴露的变量：

view->SetCameraPosition(view->GetCameraPosition() + velocity / 2.0f);

这将确保绘制调用始终使用更新后的视图矩阵而不是初始视图矩阵（之前就是这种情况，也是您麻烦的根源）。

【讨论】：

@ChrisRoss 你能展示你更新的代码吗？另外，如果你打电话给SetMatrix4beforeUse()，会有区别吗？

@ChrisRoss 只是好奇：如果你将一些不同的视图矩阵传递给你的着色器，会有什么影响吗？

在这一点上，基于当前的代码示例，我认为我们无法为您提供太多帮助；你能用你的full代码添加一个存储库的链接吗？ （请勿在此处发布代码本身）

我有点想不通；只是试图让 SDL 工作，以便我可以运行代码并调试它（希望如此）

不认为启用深度与这个问题有关，但对于实心多边形的 3D 渲染仍然是必要的