OpenGL 光照问题

Question

当我在 OpenGL 中启用光照时，我无法看到我创建的对象。我有一个从 3D Max 导入的对象，该对象的照明可以正常工作，但我的场景的其余部分却不能。我知道我需要指定法线，但这似乎没有帮助。尽管如果我在 display() 函数中创建一个可以正常工作的简单多边形，但是在类的方法中创建并在 display() 函数中调用的其他多边形没有显示出来

这是我的照明代码

glewInit();

glClearColor(0.0,0.0,0.0,0.0);
glClear(GL_COLOR_BUFFER_BIT) 

glShadeModel(GL_SMOOTH);

//light position and colour
GLfloat light_position[] = { 0.0, 0.0, 20.0,0.0 };
GLfloat white_light[] = {0.8,0.8,0.8,0.0};
GLfloat diff_light[] = {1.0,1.0,1.0,0.0};
GLfloat spec_light[] = {1.0,1.0,1.0,0.0};
glLightfv(GL_LIGHT0, GL_AMBIENT, white_light);
glLightfv(GL_LIGHT0, GL_DIFFUSE, diff_light);
glLightfv(GL_LIGHT0, GL_SPECULAR, spec_light);
glLightfv(GL_LIGHT0, GL_POSITION, light_position);

//ambient light
GLfloat ambient[] = {0.3,0.3,0.3};
glMaterialfv(GL_FRONT, GL_AMBIENT, ambient);

//diffuse material component
GLfloat diff[] = {0.6,0.6,0.6};
glMaterialfv(GL_FRONT, GL_DIFFUSE, diff);

//specular material component
GLfloat WhiteSpec[] = {1,1,1};
glMaterialfv(GL_FRONT, GL_SPECULAR, WhiteSpec);

GLfloat shininess = 50;
glMaterialf(GL_FRONT, GL_SHININESS, shininess);

//ENABLE LIGHTING AND DEPTH TEST
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);

glEnable(GL_DEPTH_TEST);

这是我创建海洋的类方法

glColor3f(0,0,1);
glPushMatrix();

//enable texturing
glEnable(GL_TEXTURE_2D);    
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glBindTexture(GL_TEXTURE_2D, seaTex);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

for(int i = 0, k = 0; i < (getWidth()/10); i++){
    for(int j = 0; j < (getLength()/10); j++){
        if(i >= Sea::waveLoc1 && i <= Sea::waveLoc1+Sea::sinArrayLength){

            int nextK = k+1;
            if(nextK == Sea::sinArrayLength){
                nextK = 0;
            }

            if(i == Sea::waveLoc1+Sea::sinArrayLength){
                //front of wave
                glBegin(GL_POLYGON);    

                glNormal3f(0.0f, 1.0f, 0.0f);   
                    glTexCoord2f(0.0, 1.0);glVertex3f(Sea::seaGrid[i][j].x, Sea::sinVals[nextK], Sea::seaGrid[i][j].z);
                    glTexCoord2f(0.0, 0.0);glVertex3f(Sea::seaGrid[i][j+1].x, Sea::sinVals[nextK], Sea::seaGrid[i][j+1].z);
                    glTexCoord2f(1.0, 0.0);glVertex3f(Sea::seaGrid[i+1][j+1].x, Sea::seaGrid[i+1][j+1].y , Sea::seaGrid[i+1][j+1].z);
                    glTexCoord2f(1.0, 1.0);glVertex3f(Sea::seaGrid[i+1][j].x, Sea::seaGrid[i+1][j].y, Sea::seaGrid[i+1][j].z);
                glEnd();
            }else{
                //rest of wave
                glBegin(GL_POLYGON);    

                glNormal3f(0.0f, 1.0f, 0.0f);   
                    glTexCoord2f(0.0, 1.0);glVertex3f(Sea::seaGrid[i][j].x, Sea::sinVals[k], Sea::seaGrid[i][j].z);
                    glTexCoord2f(0.0, 0.0);glVertex3f(Sea::seaGrid[i][j+1].x, Sea::sinVals[k], Sea::seaGrid[i][j+1].z);
                    glTexCoord2f(1.0, 0.0);glVertex3f(Sea::seaGrid[i+1][j+1].x, Sea::sinVals[nextK], Sea::seaGrid[i+1][j+1].z);
                    glTexCoord2f(1.0, 1.0);glVertex3f(Sea::seaGrid[i+1][j].x, Sea::sinVals[nextK], Sea::seaGrid[i+1][j].z);
                glEnd();
            }

        }else{
            //draw flat sea
            glBegin(GL_POLYGON);    

                glNormal3f(0.0f, 1.0f, 0.0f);

                glTexCoord2f(0.0, 1.0);glVertex3f(Sea::seaGrid[i+1][j].x, Sea::seaGrid[i+1][j].y, Sea::seaGrid[i+1][j].z);
                glTexCoord2f(0.0, 0.0);glVertex3f(Sea::seaGrid[i+1][j+1].x, Sea::seaGrid[i+1][j+1].y, Sea::seaGrid[i+1][j+1].z);
                glTexCoord2f(1.0, 0.0);glVertex3f(Sea::seaGrid[i][j+1].x, Sea::seaGrid[i][j+1].y, Sea::seaGrid[i][j+1].z);
                glTexCoord2f(1.0, 1.0);glVertex3f(Sea::seaGrid[i][j].x, Sea::seaGrid[i][j].y, Sea::seaGrid[i][j].z);
            glEnd();
        }
    }

    //increment k if i is in the area of the wave
    if(k < Sea::sinArrayLength-1 && (i >= Sea::waveLoc1 && i <= Sea::waveLoc1+Sea::sinArrayLength)){
        k++;
    }else if(k == Sea::sinArrayLength){
        k = 0;
    }
}

if(Sea::waveLoc1 < 100 && Sea::waveInc == Sea::waveSpeedLimiter){
    Sea::waveLoc1 +=1;
}else if(Sea::waveLoc1 >= 100){
    Sea::waveLoc1 = 0;
}

//limits speed of wave
if(Sea::waveInc < Sea::waveSpeedLimiter){
    Sea::waveInc++;
}else{
    Sea::waveInc = 0;
}


//disable texturing
glDisable(GL_BLEND);
glDisable(GL_TEXTURE_2D);
glPopMatrix();

然后在我的 display() 函数中调用它，如下所示

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f,(GLfloat)screenWidth/(GLfloat)screenHeight,0.1f,1000.0f);

glMatrixMode(GL_MODELVIEW);

glLoadIdentity();

camera.updateCameraPosition(mouse_x,mouse_y,screenWidth,screenHeight);


sea.buildSeaPlane();
scene.buildEdges();


glPushMatrix(); 
glColor3f(0,1,0);
glTranslatef(0, 20, 200);
model.speedDisplayFaceNormals();

glPopMatrix();

glPushMatrix();

plane.updatePlanePosition();

glBegin(GL_POLYGON);    

    glNormal3f(0.0f, 1.0f, 0.0f);

    glVertex3f(0, 25, 10);
    glVertex3f(2, 25, 10);
    glVertex3f(2, 25, 20);
    glVertex3f(0, 25, 20);
glEnd();


glPopMatrix();

glFlush();  

知道为什么我看不到这些吗？

更新：

如果我禁用纹理，我可以看到我的大海。如何修复它以便我可以使用纹理和照明？

更新 2：

已将纹理更改为 GL_MODULATE，但我还必须删除混合以使其正常工作。我需要启用混合吗？

Answer 1

尝试为整个场景添加环境光。比如：

GLfloat lightColor[] = {1.0f, 1.0f, 1.0f, 1.0f};
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lightColor);

Answer 2

在您的glMaterialfv 调用中，颜色参数应该有 4 个值，而不是 3 个。通常第 4 个值是 1.0 的 alpha。我不确定是否可以将 0.0 作为 glLightfv 的第四个值传递。

Answer 3

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

说用纹理结果替换光照计算。如果您希望光照影响纹理，请使用 GL_MODULATE 而不是 GL_REPLACE。

编辑添加：

仅当您希望几何体半透明时才需要混合（这就是混合通常用于的内容）。就您而言，代码中存在许多问题：

• 您的浅色是完全透明的（所有颜色都是 0. 作为第 4 个分量）。所以你的光让一切变得不可见。将其更改为 1。
• 您的材料没有第四个成分。更糟糕的是，glMaterialfv 需要 4 个浮点数。这甚至可能使您的应用程序崩溃或重新格式化您的磁盘。添加第四个组件，最好添加到 1. 以使其完全不透明。