VBO 不会显示(带有 glew 的 sdl)

VBO won't display (sdl with glew)

本文关键字：glew sdl 带有 显示 VBO      更新时间：2023-10-16

我刚刚开始使用VBO（使用SDL/glew）。我正在尝试从立方体的简单示例开始 - 实际上目前只是一个立方体的一个面 - 但我无法显示任何内容

我的顶点结构定义如下：

struct Vertex
{
float x, y, z;          //Vertex coords
float tx, ty;           //Texture coords
float nx, ny, nz;       //Normal coords
};

然后生成多维数据集，如下所示：

        Vertex temp;
        //NOTE: Perspective is from looking at the cube from the outside
   //Just trying to display one face for the moment to simplify
        //Back face ------------------------------------------------------------------------------------------
        temp.x = 0.f; temp.y = 0.f; temp.z = 0.f;       //Bottom Right  - 0
        temp.nx = 0.f; temp.ny = 0.f; temp.nz = 1.f; // This stays the same for the rest of the face
        temp.tx = 1.f; temp.ty = 0.f;
        m_vertices.push_back(temp);
        temp.x = 0.f; temp.y = m_fHeight; temp.z = 0.f;         //Top Right - 1
        temp.tx = 1.f; temp.ty = 1.f;
        m_vertices.push_back(temp);
        temp.x = m_fWidth; temp.y = m_fHeight; temp.z = 0.f;    //Top Left      - 2
        temp.tx = 0.f; temp.ty = 1.f;
        m_vertices.push_back(temp);
        temp.x = m_fWidth; temp.y = 0.f; temp.z = 0.f;  //Bottom Left - 3
        temp.tx = 0.f; temp.ty = 0.f;
        m_vertices.push_back(temp);
        m_indeces.push_back(0); m_indeces.push_back(1); m_indeces.push_back(2);
        m_indeces.push_back(2); m_indeces.push_back(3); m_indeces.push_back(0);

        //Generate the vertex buffer
        glGenBuffers(1, &m_vertexBufferID);
        //Bind the vertex buffer                                                                                                
        glBindBuffer(GL_ARRAY_BUFFER, m_vertexBufferID);
        //Fill the vertex buffer - size is 24*sizeof(Vertex) bcs 6 faces with 4 corners
        glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * 4, NULL, GL_STATIC_DRAW);
        glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(Vertex) * 4, &m_vertices); // Actually upload the data
        //Set up the pointers
        glTexCoordPointer(2, GL_FLOAT, sizeof(Vertex), BUFFER_OFFSET(12));
        glNormalPointer(GL_FLOAT, sizeof(Vertex), BUFFER_OFFSET(20));
        glVertexPointer(3, GL_FLOAT, sizeof(Vertex), BUFFER_OFFSET(0));

        //Generate the index buffer
        glGenBuffers(1, &m_indexBufferID);                                      
        //Bind the index buffer                                                                                         
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_indexBufferID);
        //Fill the index buffer- size is 36*sizeof(uint) bcs 6 traingle coords in 1 face * 6 faces
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GLubyte) * 6, NULL, GL_STATIC_DRAW);
        glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, sizeof(GLubyte) * 6, &m_indeces); // Actually upload the data

然后发送到一个单独的函数中渲染：

glBindBuffer(GL_ARRAY_BUFFER, vertexID);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexID);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
// Resetup the pointers. 
glTexCoordPointer(2, GL_FLOAT, sizeof(Vertex), BUFFER_OFFSET(12));
glNormalPointer(GL_FLOAT, sizeof(Vertex), BUFFER_OFFSET(20));
glVertexPointer(3, GL_FLOAT, sizeof(Vertex), BUFFER_OFFSET(0));
//Draw the indexed elements
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, BUFFER_OFFSET(0));
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_NORMAL_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);

BUFFER_OFFSET（） 是一个 simaple 宏，定义为：

// A helper macro to get a position
#define BUFFER_OFFSET(i) ((char *)NULL + (i))

但我只是无法显示任何内容 - 在即时模式下将相同的纹理等应用于立方体显示正常。

奇怪的是，偶尔会显示一些非常奇怪的东西，每次都不同 - 所以也许是某种初始化错误？

将&m_vertices和&m_indeces更改为m_vertices，并在调用glBufferSubData()中m_indeces有效！

您的尺寸都与评论不匹配，我怀疑您正在阅读 VBO 的末尾。

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