具有坐标,法线和颜色的交错式VBO

时间:2013-11-14 19:27:52

标签: c++ vbo opengl-3

我有一个关于交错vbo的问题。我有一个看起来像这样的结构

struct VertexData{
    float x,y,z;   //vertex coordinates
    float normalx,normaly,normalz;  //vertex normal
    float cx,cy,cz;  //vertex color
};

这就是我创建VBO,VAO,IBO的方式:

    //creat OpenGL objects to use in drawing
    unsigned int gl_vertex_array_object, gl_vertex_buffer_object, gl_index_buffer_object;

    //vertex array object 
    glGenVertexArrays(1, &gl_vertex_array_object);
    glBindVertexArray(gl_vertex_array_object);

    //vertex buffer object -> we hold the vertices 
    glGenBuffers(1,&gl_vertex_buffer_object);
    glBindBuffer(GL_ARRAY_BUFFER, gl_vertex_buffer_object);
    glBufferData(GL_ARRAY_BUFFER, vertices.size()*sizeof(VertexData), &vertices[0], GL_STATIC_DRAW);


    //index buffer object -> we hold the index of vertex
    glGenBuffers(1,&gl_index_buffer_object);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gl_index_buffer_object);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size()*sizeof(unsigned int), &indices[0], GL_STATIC_DRAW);

    //the connection between attributes, interleaved data
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,sizeof(VertexData),(void*)0);                       //send positions on pipe 0
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1,3,GL_FLOAT,GL_FALSE,sizeof(VertexData),(void*)(sizeof(float)*3));       //send normals on pipe 1
    glEnableVertexAttribArray(2);
    glVertexAttribPointer(2,3,GL_FLOAT,GL_FALSE,sizeof(VertexData),(void*)(3*sizeof(float)*3));     //send colors on pipe 2

    glEnableClientState(GL_NORMAL_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);
    glNormalPointer(GL_FLOAT,sizeof(VertexData),(void*)(sizeof(float)*3));   
    glColorPointer(3,GL_FLOAT,sizeof(VertexData),(void*)(3*sizeof(float)*3));

    vao = gl_vertex_array_object;
    vbo = gl_vertex_buffer_object;
    ibo = gl_index_buffer_object;
    num_indices = indices.size();

如果我的VBO是VertexData的向量,是否意味着它是交错的?我上面发送的数据是否正确?有步幅和偏移? 这一切都在另一堂课上。这是我如何加载网格并在主类

中绘制它
    //load
 teren::loadTerrain("resurse\\heightmap.bmp","resurse\\heightmap_color.bmp",mesh_vao_ground, mesh_vbo_ground, mesh_ibo_ground, mesh_num_indices_ground,20);
    //draw
    glUniformMatrix4fv(glGetUniformLocation(gl_program_shader_curent, "model_matrix"),1,false,glm::value_ptr(matrice_translatie));
    glBindVertexArray(mesh_vao_ground);
    glDrawElements(GL_TRIANGLES, mesh_num_indices_ground, GL_UNSIGNED_INT, 0);

我的地形已被绘制,但它有一种奇怪的颜色。它有粉红色和蓝色等等,看起来不像我得到我的顶点颜色的彩色图像。这是我的gourard顶点着色器:

layout(location = 0) in vec3 in_position;       
layout(location = 1) in vec3 in_normal; 
layout(location = 2) in vec3 in_color;  

uniform mat4 model_matrix, view_matrix, projection_matrix;
uniform vec3 light_position;
uniform vec3 eye_position;
uniform int material_shininess;
uniform float material_kd;
uniform float material_ks;

out vec3 light;
void main(){


gl_Position = projection_matrix*view_matrix*model_matrix*vec4(in_position,1.0); 
float fDiffuseIntensity = material_kd * max(0.0, dot(normalize(in_normal), normalize(light_position)));
light = material_ks * in_color * fDiffuseIntensity;
}

我的gourard片段着色器:

in vec3 light;
out vec4 out_color;

void main()
{
    out_color = vec4(light,1.0);
}

我现在真的被困住了。这是我的着色器或我的vbo /属性等问题,甚至两者都有问题。我真的很感激一些帮助。(PS:如果在顶点着色器中我改为light = in_color,一切都是白色的。)我也有一个在地形上方旋转的光。这是一张正在发生的事情的照片: http://i44.tinypic.com/69j0cg.jpg

1 个答案:

答案 0 :(得分:4)

这一行:

glVertexAttribPointer(2,3,GL_FLOAT,GL_FALSE,sizeof(VertexData),(void*)(3*sizeof(float)*3));

应该是:

glVertexAttribPointer(2,3,GL_FLOAT,GL_FALSE,sizeof(VertexData),(void*)(sizeof(float)*6));

你也不需要这些东西:

glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glNormalPointer(GL_FLOAT,sizeof(VertexData),(void*)(sizeof(float)*3));   
glColorPointer(3,GL_FLOAT,sizeof(VertexData),(void*)(3*sizeof(float)*3));

其余的都是正确的。


  

是否意味着它是交错的?


语言律师可能会告诉您,由于允许编译器在VertexData结构内的任何位置添加填充,将这些数据传递给GL的正确方法是手动转换VertexData的向量到漂浮物的缓冲区。实际上,没有编译器垫在这样的结构中浮动。