c++ - OpenGL 线条未着色

Question

我在 OpenGL 中工作，使用 VBO，我有一组三行(沿 X、Y 和 Z 轴 - 想想捷克刺猬)。默认情况下，这些线条是灰色的，但我希望它们是鲜红色的，这样我就能看得更清楚。不幸的是，虽然我添加了颜色信息作为顶点数据，但线条仍然显示为灰色。我可能缺少一些基本的东西，但我看不到。这是我创建 VBO 的方法:

//Position data
sf::Vector3<float> Top    = sf::Vector3<float>(0.0, 1.0, 0.0);
sf::Vector3<float> Front  = sf::Vector3<float>(0.0, 0.0, -1.0);
sf::Vector3<float> Right  = sf::Vector3<float>(1.0, 0.0, 0.0);
sf::Vector3<float> Back   = sf::Vector3<float>(0.0, 0.0, 1.0);
sf::Vector3<float> Left   = sf::Vector3<float>(-1.0, 0.0, 0.0);
sf::Vector3<float> Bottom = sf::Vector3<float>(0.0, -1.0, 0.0);

//Color data
//Just to be clear, I also tried with 255.0, although I'm rather certain OpenGL 
//does its colors on a 0-1 scale.
sf::Vector3<float> Color = sf::Vector3<float>(1.0, 0.0, 0.0);

//Create vector
std::vector<float> LineArray;

//Top
LineArray.push_back(Top.x);
LineArray.push_back(Top.y);
LineArray.push_back(Top.z);
LineArray.push_back(Color.x);
LineArray.push_back(Color.y);
LineArray.push_back(Color.z);
//Bottom
LineArray.push_back(Bottom.x);
LineArray.push_back(Bottom.y);
LineArray.push_back(Bottom.z);
LineArray.push_back(Color.x);
LineArray.push_back(Color.y);
LineArray.push_back(Color.z);

//Front
LineArray.push_back(Front.x);
LineArray.push_back(Front.y);
LineArray.push_back(Front.z);
LineArray.push_back(Color.x);
LineArray.push_back(Color.y);
LineArray.push_back(Color.z);
//Back
LineArray.push_back(Back.x);
LineArray.push_back(Back.y);
LineArray.push_back(Back.z);
LineArray.push_back(Color.x);
LineArray.push_back(Color.y);
LineArray.push_back(Color.z);

//Right
LineArray.push_back(Right.x);
LineArray.push_back(Right.y);
LineArray.push_back(Right.z);
LineArray.push_back(Color.x);
LineArray.push_back(Color.y);
LineArray.push_back(Color.z);
//Left
LineArray.push_back(Left.x);
LineArray.push_back(Left.y);
LineArray.push_back(Left.z);
LineArray.push_back(Color.x);
LineArray.push_back(Color.y);
LineArray.push_back(Color.z);

//Create buffer
glGenBuffers(1, &m_Buffer);
glBindBuffer(GL_ARRAY_BUFFER, m_Buffer);
int SizeInBytes = LineArray.size() * 6 * sizeof(float);
glBufferData(GL_ARRAY_BUFFER, SizeInBytes, NULL, GL_STATIC_DRAW);

//Upload buffer data
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(float) * LineArray.size(), &LineArray[0]);

这就是我每次显示它的方式:

glPushMatrix();

//Translate
glTranslatef(m_Position.x, m_Position.y, m_Position.z);
//Rotate
glMultMatrixf(m_RotationMatrix);

//Bind buffers for vertex and color arrays
glBindBuffer(GL_ARRAY_BUFFER, m_Buffer);

glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 6 * sizeof(float), 0);
glEnableClientState(GL_COLOR_ARRAY);
glColorPointer(3, GL_FLOAT, 6 * sizeof(float), (void*)12);

//Draw
glDrawArrays(GL_LINES, 0, 36);

glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);

//Unbind the buffers
glBindBuffer(GL_ARRAY_BUFFER, 0);

glPopMatrix();

我以前从未使用过 GL_COLOR_ARRAY，但我的代码基于成功使用 GL_NORMAL_ARRAY。有人可以指出问题所在吗？

编辑:万一我设置了错误的基本 OpenGL 参数(特别是光照)，这里是那些:

m_AmbientLight = {0.5f, 0.5f, 0.5f, 1.0f};
m_DiffuseLight = {1.0f, 1.0f, 1.0f, 1.0f};
m_LightPos = {8.0f, -16.0f, 8.0f, 0.0f};

//Smooth Shading
glShadeModel(GL_SMOOTH);

// Set color and depth clear value
glClearDepth(1.f);
//Color here is in RGB, converted to a 0-1 scale.
glClearColor(0.3f, 0.3f, 0.3f, 1.f);

// Enable Z-buffer read and write
glEnable(GL_DEPTH_TEST);
glDepthMask(GL_TRUE);

///
///LIGHTING
///
//Set up lighting.
//This activates the ambient light.
glLightfv(GL_LIGHT0, GL_AMBIENT, m_AmbientLight);
//This activates the diffuse light.
glLightfv(GL_LIGHT1, GL_DIFFUSE, m_DiffuseLight);
//This sets the position of the diffuse light.
glLightfv(GL_LIGHT1, GL_POSITION, m_LightPos);
//This enables the light.
glEnable(GL_LIGHT0);
glEnable(GL_LIGHT1);
//Enables all lighting...?
glEnable(GL_LIGHTING);
glEnable(GL_COLOR_MATERIAL);
//glEnable(GL_NORMALIZE);

// Setup a perspective projection
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60.f, 1.33f, 0.1f, 512.f);

编辑 2:确定 glColor3f() 也没有任何效果后，我想知道是不是我的着色器出了问题:

垂直着色器:

void main()
{
vec3 normal, lightDir;
vec4 diffuse;
float NdotL;

normal = normalize(gl_NormalMatrix * gl_Normal);

lightDir = normalize(vec3(gl_LightSource[0].position));

NdotL = max(dot(normal, lightDir), 0.0);

diffuse = gl_FrontMaterial.diffuse * gl_LightSource[0].diffuse;
gl_FrontColor =  NdotL * diffuse;

gl_Position = ftransform();
}

片段着色器:

void main()
{
gl_FragColor = gl_Color;
}

Answer 1

并非 100% 肯定，但我认为您在绘制线条时不应该启用 GL_COLOR_MATERIAL。尝试禁用它。

编辑(从评论中复制):

你的着色器对我来说没有意义。您应该只传递一种颜色，然后将该颜色直接传递给片段着色器。为什么要使用光照着色器绘制线条？您应该创建一个不使用任何 Material 的不同着色器。除非您使用固定功能管道，否则启用/禁用照明没有任何效果。我认为您将固定功能命令与着色器混在一起并感到困惑。