Question

我来自这个问题:

https://stackoverflow.com/questions/4837774/opengl-vbo-advice>opengl vbovis

我使用开放式GL3.3,不会使用假装。采用Assimp进口我的模版模型。但是,从VAO 和VBO 来看,对于他们应当有多少人分开,似乎有些混淆。

首先谈一点。我使用冰川,这确实意味着不能回避我的垂直属性,或者世界动物联盟能够利用冰川和冰川抵消,看看我的垂直位置在哪里?

主要问题一、gues、如何构造我的VAO/VBO为具有多个移动部分的模型,以及多片镜子。

Each node in assimp can contain multiple meshes where each mesh has texture, vertices, normals, material etc. The nodes in assimp contains the transformations. Say i have a ship with a cannon turret on it. I want to be able to roatate the turret. Do this mean i will make the ship node a seperate VAO with VBO s for each mesh containing its attributes(or multiple VBO s etc.). I guess it goes like

draw(ship);    //call to draw ship VAO
pushMatrix(turretMatrix)  //updating uniform modelview matrix for the shader
draw(turret);  //call to draw turret VAO

I don t fully understand UBO(uniform buffer objects) yet, but it seems i can pass in multiple uniforms, will that help me contain a full model with moveable parts in a single VAO?

Answer 1

首先,在VAO之外,只有“成员”最后的纵向归属约束(以及VBO对指数缓冲(GL_ELEMENT_ARRAY_BUFFER_BINDING)具有约束力,如果有的话。因此,在<条码>glDrawElements()中,你无需记住这一点,在使用日志时,你必须说这一点。它不妨碍你使用环绕阵列。请允许我解释:

int vbo[3];
glGenBuffers(3, vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
glBufferData(GL_ARRAY_BUFFER, data0, size0);
glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
glBufferData(GL_ARRAY_BUFFER, data1, size1);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vbo[2]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, data2, size2);
// create some buffers and fill them with data

int vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
// create a VAO

{
    glBindBuffer(GL_ARRAY_BUFFER, vbo[0]); // not saved in VAO
    glVertexAttribPointer(0, 3, GL_FLOAT, false, 3 * sizeof(float), NULL); // this is VAO saved state
    glEnableVertexAttribArray(0); // this is VAO saved state
    // sets up one vertex attrib array from vbo[0] (say positions)

    glBindBuffer(GL_ARRAY_BUFFER, vbo[1]); // not saved in VAO
    glVertexAttribPointer(1, 3, GL_FLOAT, false, 5 * sizeof(float), NULL); // this is VAO saved state
    glVertexAttribPointer(2, 2, GL_FLOAT, false, 5 * sizeof(float), (const void*)(2 * sizeof(float))); // this is VAO saved state
    glEnableVertexAttribArray(1); // this is VAO saved state
    glEnableVertexAttribArray(2); // this is VAO saved state
    // sets up two more VAAs from vbo[1] (say normals interleaved with texcoords)

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vbo[2]); // this is VAO saved state
    // uses the third buffer as the source for indices
}
// set up state that VAO "remembers"

glBindVertexArray(0); // bind different vaos, etc ...

后来......

glBindVertexArray(vao); // bind our VAO (so we have VAAs 0, 1 and 2 as well as index buffer)
glDrawElements(GL_TRIANGLE_STRIP, 57, GL_UNSIGNED_INT, NULL);
glDrawElements(GL_TRIANGLE_STRIP, 23, GL_UNSIGNED_INT, (const void*)(57 * sizeof(unsigned int)));
// draws two parts of the mesh as triangle strips

因此,请见......您使用单一甚小分辨率和一个或多个甚低分辨率分辨率分辨率阵列。

为了回答你提问的第二部分,您要么可以有不同的甚小分辨率和低分辨率分辨率分辨率分数,要么可以将其全部用到一个千分辨率高分辨率高的舱面(因此,你不需要打上<代码>glBind*() ,并且使用多个密码) 电话,以提取小小小小小小小小小小小sh(如上面的代码所示) ——想象第一部<编码>(glDrawElements() 船舶,而第2版) 检索,你只是更新中间线。

由于浏览器可以包含多种穿制服的模型矩阵,因此,你还可以将斜体编码为另一个垂直特性,让透镜选择根据这一特性将哪些矩阵用于改变垂直。也可将这一想法扩大到使用每个单项中值的多个矩阵,每个矩阵的加权数。这通常用于对诸如角色特性(ook“亲属”)等有机物进行估算。

作为统一的缓冲物体,唯一的好处是,你能够把许多数据包装到这些物体中,并且能够很容易地在弹).之间分享(使UBO与能够使用的任何弹).合)。在为你使用这些物品方面没有任何实际好处,除非您有1OOO基斯的物体。

Also, i wrote the source codes above from memory. Let me know if there are some errors / problems ...

Answer 2

@theswine

Not binding this during VAO initialization causes my program to crash, but binding it after binding the VAO causes it to run correctly. Are you sure this isn t saved in the VAO?

glBindBuffer(GL_ARRAY_BUFFER, vbo[0]); // not saved in VAO

(BTW: 抱歉提出老话题,我只是认为这对其他人有用,这肯定是!) (这提醒我,感谢你!)

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