[英]OpenGL Duplicating Vertex Arrays
我正在寻找一些有关重复数组中已有索引的说明和指导,我需要从收集重复索引的内容中进行渲染,以便渲染一个立方体(每边各有不同的颜色)。 我的多维数据集是从“ OBJ”文件中读取的。
当前代码
using std::vector;
vector<GLfloat>vertex;
vector<GLuint>faces;
GLubyte color1[] =
{
255,255,0,
255,255,0,
255,255,0,
255,255,0,
255,0,255,
255,0,255,
255,0,255,
255,0,255
};
struct OBJVertex
{
GLint f1;
GLint f2;
GLint f3;
GLfloat x;
GLfloat y;
GLfloat z;
}obj;
int OBJLoader::LoadOBJData(string filename)
{
ifstream f_obj;
string line;
f_obj.open(filename, ios::in);
while (!f_obj.eof())
{
getline(f_obj, line);
if (line.find("v") != line.npos)
{
sscanf_s(line.c_str(), "v %f %f %f ", &obj.x, &obj.y, &obj.z);
vertex.push_back(obj.x);
vertex.push_back(obj.y);
vertex.push_back(obj.z);
}
if (line.find("f ")!= line.npos)
{
sscanf_s(line.c_str(), "f %d %d %d ", &obj.f1, &obj.f2, &obj.f3);
obj.f1 = obj.f1 - 1;
obj.f2 = obj.f2 - 1;
obj.f3 = obj.f3 - 1;
faces.push_back(obj.f1);
faces.push_back(obj.f2);
faces.push_back(obj.f3);
}
}
return 0;
}
void OBJLoader::RenderOBJ()
{
glEnable(GL_DEPTH_TEST);
glEnableClientState(GL_COLOR_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glColorPointer(3, GL_UNSIGNED_BYTE, 0, color1);
glVertexPointer(3,GL_FLOAT, 0, &vertex[0]);
glDrawElements(GL_TRIANGLE_STRIP,faces.size(),GL_UNSIGNED_INT,&faces[0]);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);
}
我是否认为需要使用glBindBuffer绑定顶点和颜色数组是否正确?
glBindBuffer(GL_ARRAY_BUFFER,vertex[0]);
我目前有一个名为“ color1”的颜色阵列设置,该颜色在绑定第一个顶点和颜色阵列后为立方体的顶面和底面着色
理念?
glEnableClientState(GL_COLOR_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glColorPointer(3, GL_UNSIGNED_BYTE, 0, color1); // first colour array //
glVertexPointer(3,GL_FLOAT, 0, &vertex[0]);
glDrawElements(GL_TRIANGLE_STRIP, faces.size(), GL_UNSIGNED_INT,&faces[0]);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);
glBindBuffer(GL_ARRAY_BUFFER,vertex[0]);
glEnableClientState(GL_COLOR_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glColorPointer(3, GL_UNSIGNED_BYTE, 0, color2); // second colour array //
glVertexPointer(3,GL_FLOAT, 0, &vertex[0]);
glDrawElements(GL_TRIANGLE_STRIP, faces.size(), GL_UNSIGNED_INT,&faces[0]);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);
glBindBuffer(GL_ARRAY_BUFFER,vertex[0]);
----更新----
抱歉,但是我每张脸都做了一个彩色阵列,但它只是覆盖了以前的阵列,有人可以解释我做得不好吗?
GLubyte color1[] =
{
255,255,0,
255,255,0,
255,255,0,
255,255,0,
255,0,255,
255,0,255,
255,0,255,
255,0,255
};
GLubyte color2[] =
{
255,0,0,
255,0,0,
255,0,0,
255,0,0,
0,0,255,
0,0,255,
0,0,255,
0,0,255
};
GLubyte color3[] =
{
0,255,255,
0,255,255,
0,255,255,
0,255,255,
255,0,255,
255,0,255,
255,0,255,
255,0,255
};
GLubyte color4[] =
{
255,255,255,
255,255,255,
255,255,255,
255,255,255,
0,255,0,
0,255,0,
0,255,0,
0,255,0
};
void OBJLoader::RenderOBJ()
{
glEnable(GL_DEPTH_TEST);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, &vertex[0]);
glColorPointer(3, GL_UNSIGNED_BYTE, 0, color1);
glColorPointer(3, GL_UNSIGNED_BYTE, 0, color2);
glColorPointer(3, GL_UNSIGNED_BYTE, 0, color3);
glColorPointer(3, GL_UNSIGNED_BYTE, 0, color4);
glDrawElements(GL_TRIANGLE_STRIP, faces.size(), GL_UNSIGNED_INT, &faces[0]);
glDrawElements(GL_TRIANGLE_STRIP, faces.size(), GL_UNSIGNED_INT, &faces[0]);
glDrawElements(GL_TRIANGLE_STRIP, faces.size(), GL_UNSIGNED_INT, &faces[0]);
glDrawElements(GL_TRIANGLE_STRIP, faces.size(), GL_UNSIGNED_INT, &faces[0]);
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
}
---- OBJ ----
v 1.000000 -1.000000 -1.000000
v 1.000000 -1.000000 1.000000
v -1.000000 -1.000000 1.000000
v -1.000000 -1.000000 -1.000000
v 1.000000 1.000000 -1.000000
v 1.000000 1.000000 1.000000
v -1.000000 1.000000 1.000000
v -1.000000 1.000000 -1.000000
f 5 1 4
f 5 4 8
f 3 7 8
f 3 8 4
f 2 6 3
f 6 7 3
f 1 5 2
f 5 6 2
f 5 8 6
f 8 7 6
f 1 2 3
f 1 3 4
在您的情况下,您根本不需要绑定缓冲区,因为您将缓冲区的索引直接发送到glColorPointer()
。
可以将其视为直接将指向缓冲区的指针发送到OpenGL进行读取。 您可以创建更多的颜色缓冲区,只需更改glColorPointer()
。
glColorPointer(3, GL_UNSIGNED_BYTE, 0, color2);
//...
glColorPointer(3, GL_UNSIGNED_BYTE, 0, color3);
另外,您也可以将所有颜色放在一个称为color的缓冲区中,然后简单地传递正确的偏移量。 假设您在一个缓冲区中有72种用于三种颜色的成分,则可以这样做。
glColorPointer(3, GL_UNSIGNED_BYTE, 0, &color[0]);
//...
glColorPointer(3, GL_UNSIGNED_BYTE, 0, &color[24]);
//...
glColorPointer(3, GL_UNSIGNED_BYTE, 0, &color[48]);
仅当传递像这样的空指针时,才需要绑定缓冲区
//setup your array buffer
GLuint colorBuffID;
glGenBuffers(1, &colorBuffID);
glBindBuffer(GL_ARRAY_BUFFER, colorBuffID);
glBufferData(GL_ARRAY_BUFFER, 24 * sizeof(unsigned char), color1, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
//...
//use your array buffer
glBindBuffer(GL_ARRAY_BUFFER, colorBuffID);
glColorPointer( 3, GL_UNSIGNED_BYTE, 0, (const void*)( 0 ) );
// draw the quad
glBindBuffer(GL_ARRAY_BUFFER, 0);
如果在指定颜色数组时将非零命名缓冲区对象绑定到GL_ARRAY_BUFFER目标(请参阅glBindBuffer),则将指针视为缓冲区对象数据存储区中的字节偏移量。 另外,缓冲区对象绑定(GL_ARRAY_BUFFER_BINDING)被保存为颜色顶点数组客户端状态(GL_COLOR_ARRAY_BUFFER_BINDING)。
请参阅https://www.opengl.org/sdk/docs/man2/xhtml/glColorPointer.xml
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