Skybox没有渲染

Question

我试图渲染天空框在我的场景，但它呈现黑色的纹理是不正确的加载。我使用FreeImage库加载纹理：

#include <FreeImage.h>

这是我的Skybox课程：

#include "Skybox.h"


CSkybox::CSkybox(){
    el::Logger* logger = el::Loggers::getLogger("Skybox");
}

void CSkybox::init(string home_dir, string pos_x, string neg_x, string pos_y, string neg_y, string pos_z, string neg_z)
{
    cubeFilesPaths[0] = home_dir+pos_x;
    cubeFilesPaths[1] = home_dir+neg_x;
    cubeFilesPaths[2] = home_dir+pos_y;
    cubeFilesPaths[3] = home_dir+neg_y;
    cubeFilesPaths[4] = home_dir+pos_z;
    cubeFilesPaths[5] = home_dir+neg_z;

    loadShaders("shaders/skyboxShader.vp", "shaders/skyboxShader.fp");

    glGenTextures(1, &cubeTexture);
    glBindTexture(GL_TEXTURE_CUBE_MAP, cubeTexture);

    for(int i = 0; i < 6; i++){        
        verify(readTexture(i), "Texture "+cubeFilesPaths[i]+" not loaded"); 
    }

    CLOG(INFO, "Skybox")<<"Skybox texture loaded.";

    vao.createVAO();
    vao.bindVAO();
}

void CSkybox::loadShaders(string vsPath, string fsPath){
    verify(skyboxVertexShader.loadShader(vsPath, GL_VERTEX_SHADER), "Skybox vertex shader not loaded");
    verify(skyboxFragmentShader.loadShader(fsPath, GL_FRAGMENT_SHADER), "Skybox fragment shader not loaded");

    skyboxShaderProgram.createProgram();
    verify(skyboxShaderProgram.addShaderToProgram(&skyboxVertexShader), "Skybox vertex shader not added to a program");
    verify(skyboxShaderProgram.addShaderToProgram(&skyboxFragmentShader), "Skybox fragment shader not added to a program");

    verify(skyboxShaderProgram.linkProgram(), "Shader program not linked"); 
}

void CSkybox::render(glm::mat4 viewMatrix){
    //glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
    //glDisable(GL_CULL_FACE);

    skyboxShaderProgram.bindProgram();
    vao.bindVAO();

    skyboxShaderProgram.setUniform("view_matrix", &viewMatrix);
    glBindTexture(GL_TEXTURE_CUBE_MAP, cubeTexture);

    glDisable(GL_DEPTH_TEST);
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
    glEnable(GL_DEPTH_TEST);

    vao.unbindVAO();
    //glEnable(GL_CULL_FACE);
    skyboxShaderProgram.unbindProgram();
    //glPolygonMode(GL_FRONT, GL_FILL);
}

void CSkybox::release(){
    glDeleteTextures(1, &cubeTexture);
    skyboxShaderProgram.deleteProgram();
    skyboxVertexShader.deleteShader();
    skyboxFragmentShader.deleteShader();
    vao.releaseVAO();
}

bool CSkybox::readTexture(int i){
    cout<<"Reading: "<<i<<endl;

    FREE_IMAGE_FORMAT fif = FIF_UNKNOWN;
    FIBITMAP* dib(0);

    fif = FreeImage_GetFileType(cubeFilesPaths[i].c_str(), 0); // Check the file signature and deduce its format

    if(fif == FIF_UNKNOWN) // If still unknown, try to guess the file format from the file extension
        fif = FreeImage_GetFIFFromFilename(cubeFilesPaths[i].c_str());

    if(fif == FIF_UNKNOWN) // If still unknown, return failure
        return false;

    if(FreeImage_FIFSupportsReading(fif)) // Check if the plugin has reading capabilities and load the file
        dib = FreeImage_Load(fif, cubeFilesPaths[i].c_str());
    if(!dib)
        return false;

    BYTE* bits = FreeImage_GetBits(dib); // Retrieve the image data

    // If somehow one of these failed (they shouldn't), return failure
    if(bits == NULL || FreeImage_GetWidth(dib) == 0 || FreeImage_GetHeight(dib) == 0)
        return false;

    cout<<FreeImage_GetBPP(dib)<<endl;

    GLenum format = FreeImage_GetBPP(dib) == 24 ? GL_BGR : FreeImage_GetBPP(dib) == 8 ? GL_LUMINANCE : 0;
    GLenum internalFormat = FreeImage_GetBPP(dib) == 24 ? GL_RGB : GL_DEPTH_COMPONENT;
    GLsizei iWidth = FreeImage_GetWidth(dib);
    GLsizei iHeight = FreeImage_GetHeight(dib);

    cout<<iWidth<<endl;
    cout<<iHeight<<endl;

    glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, internalFormat, iWidth, iHeight, 0, format, GL_UNSIGNED_BYTE, bits);

    GLenum error = glGetError();
    if(error!= GL_NO_ERROR){
        cout<<error<<endl;
    }

    FreeImage_Unload(dib);
    return true;
}

void CSkybox::verify(bool value, string message){
    if(!value){
        CLOG(ERROR, "Skybox")<<"Error: "<<message;
    }
}

顶点着色器：

#version 430 core

out VS_OUT
{
    vec3 tc;
} vs_out;

uniform mat4 view_matrix;

void main(void)
{
    vec3[4] vertices = vec3[4](vec3(-1.0, -1.0, 1.0),
                               vec3( 1.0, -1.0, 1.0),
                               vec3(-1.0,  1.0, 1.0),
                               vec3( 1.0,  1.0, 1.0));

    vs_out.tc = mat3(view_matrix) * vertices[gl_VertexID];

    gl_Position = vec4(vertices[gl_VertexID], 1.0);
}

和碎片着色器：

#version 430 core

layout (binding = 0) uniform samplerCube tex_cubemap;

in VS_OUT
{
    vec3    tc;
} fs_in;

layout (location = 0) out vec4 color;

void main(void)
{
    color = texture(tex_cubemap, fs_in.tc);
}

不幸的是，render()方法只呈现一个黑色矩形。如果我硬编码片段着色器中的另一种颜色或顶点着色器中的顶点同义词，矩形会改变颜色和位置。我也使用着色器和vao助手类来渲染粒子，所以它们可能是好的，问题在于纹理加载。

最终效果如下：

​

​

Answer 1

至少有两个不同的变量名为cubeEnum

在函数范围内，在cubeEnum构造函数中声明了一个CSkybox：

CSkybox::CSkybox(){
    el::Logger* logger = el::Loggers::getLogger("Skybox");

    GLenum  cubeEnum[6] = {  GL_TEXTURE_CUBE_MAP_POSITIVE_X,
        GL_TEXTURE_CUBE_MAP_NEGATIVE_X,
        GL_TEXTURE_CUBE_MAP_POSITIVE_Y,
        GL_TEXTURE_CUBE_MAP_NEGATIVE_Y,
        GL_TEXTURE_CUBE_MAP_POSITIVE_Z,
        GL_TEXTURE_CUBE_MAP_NEGATIVE_Z };
}

还有另一个cubeEnum声明在readTexture (...)使用的不同范围内。

glTexImage2D(cubeEnum[i], 0, internalFormat, iWidth, iHeight, 0, format, GL_UNSIGNED_BYTE, bits);

我怀疑另一个也称为cubeEnum的数组未初始化，因此将垃圾传递给glTexImage2D (...)。然而，简单的事实是，首先不需要数组。

这组特定的枚举是连续的，因此您可以编写以下内容：

glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, internalFormat, iWidth, iHeight, 0, format, GL_UNSIGNED_BYTE, bits);

并去掉所有您已经命名为cubeEnum的独立变量。那么，您将不再需要在不同的范围内跟踪同名的变量。

更新：

此外，您在没有适当的mipmap LOD集的cubemap上使用默认的纹理缩小筛选器：GL_NEAREST_MIPMAP_LINEAR (GL纹理在默认情况下具有1000 LOD，您只定义了LOD )。在"mipmap不完全“纹理上使用该筛选器会导致未定义的行为，这是导致您的黑色纹理的原因。