Question

我正在使用OpenGL和c ++构建一个应用程序，以在屏幕上显示透明对象，周围有多个灯光，并模拟透明对象可能产生的不同反射。然后，我将在固定摄像机位置拍摄屏幕快照，并随机移动对象以模拟反射，并将其与文件名相同的文本文件一起另存为本地文件中的BMP文件。

接下来，我需要获取对象在窗口坐标[x，y]中的位置并将其保存在我的输出文本文件中。

现在对我来说问题是要获取对象在窗口坐标中的位置。创建的窗口为1920 X1080。我需要对象的中心位置与[x * y]相同。

这是我的主要cpp文件

int RandGenerator()
{

std::random_device rd;
std::default_random_engine generator(rd());
std::uniform_real_distribution<double> distribution(-3.0, 3.0);
double number = distribution(generator);    

std::this_thread::sleep_for(std::chrono::milliseconds(100));

return number;

}

int RandGenerator_1()
{

std::random_device rd;
std::default_random_engine generator(rd());
std::uniform_real_distribution<double> distribution(-3.0, 3.0); 
double number1 = distribution(generator);
std::this_thread::sleep_for(std::chrono::milliseconds(100));

return number1;

}


int main()
{
mainWindow = Window(1920, 1080);    
mainWindow.initialise();

CreateObjects();
CreateShaders();

camera = Camera(glm::vec3(0.0f, 0.0f, 7.0f), glm::vec3(0.0f, 1.0f, 0.0f), 
-90.0f, 0.0f, 5.0f, 0.2f);

shinyMaterial = Material(4.0f, 156);
dullMaterial = Material(0.5f, 4);

groundfloor = Model();
groundfloor.LoadModel("res/models/blender/Floor.obj");  

blackhawk = Model();
blackhawk.LoadModel("res/models/blender/cup.obj");

cup2 = Model();
cup2.LoadModel("res/models/blender/cup.obj");

mainLight = DirectionalLight(1.0f, 1.0f, 1.0f, 
                            0.1f, 0.1f, 
                            0.5f, -1.0f, 20.0f);

unsigned int pointLightCount = 0;

pointLights[0] = PointLight(0.0f, 0.0f,1.0f,
                            1.0f, 1.0f,
                            3.0f, 0.0f, 1.0f,
                            1.0f, 0.2f, 0.1f);

pointLightCount++;

pointLights[1] = PointLight(1.0f, 1.0f, 1.0f,
                            1.0f, 1.0f,
                            -3.0f, 0.0f, 1.0f,
                            1.0f, 0.2f, 0.1f);

pointLightCount++;  


GLuint uniformProjection = 0, uniformModel = 0, uniformView = 0, 
   uniformEyePosition = 0,
       uniformSpecularIntensity =0,uniformShininess = 0;
glm::mat4 projection = glm::perspective(45.0f, 
 (GLfloat)mainWindow.getBufferWidth() / 
 (GLfloat)mainWindow.getBufferHeight(), 
 0.1f, 100.0f); 

//Main game Loop 
while (!mainWindow.getShouldClose()) 
{
    GLfloat now = glfwGetTime();
    deltaTime = now - lastTime;
    lastTime = now;

    // Handle user inputs and events
    glfwPollEvents();

    camera.keyControl(mainWindow.getKeys(), deltaTime);
    camera.mouseControl(mainWindow.getXchange(), mainWindow.getYchange());

    //clear the window
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    shaderList[0].UseShader();
    uniformProjection = shaderList[0].GetProjectionLocation();
    uniformModel = shaderList[0].GetModelLocation();
    uniformView = shaderList[0].GetViewLocation();
    uniformEyePosition = shaderList[0].GetEyePosition();
    uniformSpecularIntensity = shaderList[0].GetSpecularIntensityLoc();
    uniformShininess = shaderList[0].GetShininessLoc();

    glm::vec3 lowerLight = camera.GetCameraPosition();
    lowerLight.y -= 0.3f;

    glm::vec3 camerayaw = camera.GetCameraDirection();

    glm::vec3 dlightPos = mainLight.GetLightPos();      

    shaderList[0].SetDirectionalLight(&mainLight);
    shaderList[0].SetPointLights(pointLights, pointLightCount);
    shaderList[0].SetSpotLights(spotLights, spotLightCount);        

    glUniformMatrix4fv(uniformProjection, 1, GL_FALSE, 
    glm::value_ptr(projection));
    glUniformMatrix4fv(uniformView, 1, GL_FALSE, 
    glm::value_ptr(camera.calulateViewMatrix()));
    glUniform3f(uniformEyePosition, camera.GetCameraPosition().x, 
    camera.GetCameraPosition().y, camera.GetCameraPosition().z);        

    glEnable(GL_DEPTH_TEST);

    model = glm::mat4(1.0f);
    model = glm::translate(model, glm::vec3(0.0f, 0.0f, -0.46f));
    model = glm::scale(model, glm::vec3(0.5f, 0.5f, 0.5f));
    model = glm::rotate(model, 90.0f*toRad, glm::vec3(1.0f, 0.0f, 0.0f));
    glUniformMatrix4fv(uniformModel, 1, GL_FALSE, glm::value_ptr(model));
    dullMaterial.UseMaterial(uniformSpecularIntensity, uniformShininess);
    groundfloor.RenderModel();              

    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glCullFace(GL_BACK);
    glEnable(GL_CULL_FACE);
    glDepthMask(GL_FALSE);

    glm::vec3 translation(RandGenerator(), RandGenerator_1(), 0.0f);

    model = glm::mat4(1.0f);
    model = glm::translate(model, translation);
    model = glm::scale(model, glm::vec3(1.0f, 1.0f, 1.0f));
    viewmat = camera.calulateViewMatrix();
    glm::mat4 model_view = projection * viewmat * model;        
    glUniformMatrix4fv(uniformModel, 1, GL_FALSE, glm::value_ptr(model));
    shinyMaterial.UseMaterial(uniformSpecularIntensity, uniformShininess);
    blackhawk.RenderModel();

    glDisable(GL_CULL_FACE);
    glDisable(GL_BLEND);        
    glDepthMask(GL_TRUE);


    glUseProgram(0);

    mainWindow.swapBuffers();
}

return 0;}

这是我的Vertex Shader文件

#version 330

layout (location =0) in vec3 pos;
layout (location =1) in vec2 tex;
layout (location =2) in vec3 normal;

out vec4 vCol;
out vec2 TexCoords;
out vec3 NormalValue;
out vec3 FragPos;


uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
uniform vec3 clipSpacePos;

void main()
{
gl_Position = projection * view *  model* vec4(pos, 1.0f);  

vCol = vec4(clamp(pos, 0.0f, 1.0f), 0.2f);

TexCoords = tex;

NormalValue = mat3(transpose(inverse(model))) * normal;

FragPos = (model* vec4(pos, 1.0f)).xyz;
}

如果问题很基本，请原谅我，我是OpenGL以及编程方面的初学者。预先感谢，输出图像：

Answer 1

要从场景坐标中获取屏幕坐标，您需要在其上应用所有变换矩阵并执行透视划分。

您没有提供任何示例代码，因此不清楚您是使用旧API还是使用新API ...以及所获得的矩阵（或其他任何形式）和乘法顺序...

请参阅以下两个相关的质量检查：

有关数学知识的方法。

现在什么样的反射和透明度？

对于真正的交易，您需要光线跟踪渲染

例如这样的东西：
- Reflection and refraction impossible without recursive ray tracing?
但是这些通常很耗时...
对于廉价的假货，您可以使用Blending +环境立方体贴图技术

透明性可以这样完成：
- How to create Order Independent transparency?
对于反射，您只需添加环境立方体贴图。这意味着您在GL_CUBE_MAP_TEXTURE中有一个（环境中的）天空盒，并计算从表面法线和方向到相机的反射光线...并在结果颜色中添加相应的立方体贴图纹理元素...旧样式的API，但更容易的是使用着色器。

如何在窗口坐标中获取模型（对象）的位置

1 个答案: