glDrawArray和glDrawElements在一个程序中崩溃

Question

void init_cube(void){
        makeCube(cbr_points,cbr_normals);
        glGenVertexArrays(1,&VAID_cube);
        glBindVertexArray(VAID_cube);

        glGenBuffers(1,&VBID_cube);
        glBindBuffer(GL_ARRAY_BUFFER,VBID_cube);
        glBufferData(GL_ARRAY_BUFFER,sizeof(vec4)*cbr_points.size()+sizeof(vec3)*cbr_normals.size(),0,GL_STATIC_DRAW);
        glBufferSubData(GL_ARRAY_BUFFER,0,cbr_points.size()*sizeof(vec4),cbr_points.data());
        glBufferSubData(GL_ARRAY_BUFFER,cbr_points.size()*sizeof(vec4),cbr_normals.size()*sizeof(vec3),cbr_normals.data());

        GLuint vPosition = glGetAttribLocation(g_IDShader,"vPosition");
        glEnableVertexAttribArray(vPosition);
        glVertexAttribPointer(vPosition,4,GL_FLOAT,GL_FALSE,0,BUFFER_OFFSET(0));

        GLuint vNormal = glGetAttribLocation(g_IDShader,"vNormal");
        glEnableVertexAttribArray(vNormal);
        glVertexAttribPointer(vNormal,3,GL_FLOAT,GL_FALSE,0,BUFFER_OFFSET(cbr_points.size()*sizeof(vec4)));
}

void setVAVBObject( void )
{
    // Set VAO
    glGenVertexArrays   ( 1, &g_VAID );
    glBindVertexArray   ( g_VAID );

    // Set vertex position, normal and elements - VBO
    glGenBuffers    ( 1, &g_VBIDvertices );
    glBindBuffer    ( GL_ARRAY_BUFFER, g_VBIDvertices );
    glBufferData    ( GL_ARRAY_BUFFER, g_bunny.vertices.size() * sizeof(g_bunny.vertices[0]),   g_bunny.vertices.data(), GL_STATIC_DRAW );

    glGenBuffers    ( 1, &g_VBIDnormals );
    glBindBuffer    ( GL_ARRAY_BUFFER, g_VBIDnormals );
    glBufferData    ( GL_ARRAY_BUFFER, g_bunny.normals.size() * sizeof(g_bunny.normals[0]), g_bunny.normals.data(), GL_STATIC_DRAW );

    // Ex-TODO: Computing normal
    // Set up the indices buffer - flat shading does not use indices

    glGenBuffers ( 1, &g_IBIDelements );
    glBindBuffer ( GL_ELEMENT_ARRAY_BUFFER, g_IBIDelements );
    glBufferData ( GL_ELEMENT_ARRAY_BUFFER,
                        g_bunny.elements.size() * sizeof(g_bunny.elements[0]),
                        g_bunny.elements.data(), GL_STATIC_DRAW );


    GLuint vPosition = glGetAttribLocation( g_IDShader, "vPosition" );
    glEnableVertexAttribArray( vPosition );
    glBindBuffer( GL_ARRAY_BUFFER, g_VBIDvertices);
    glVertexAttribPointer( vPosition, 4, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0) );

    GLuint vNormal = glGetAttribLocation( g_IDShader, "vNormal" );
    glEnableVertexAttribArray( vNormal );
    glBindBuffer( GL_ARRAY_BUFFER, g_VBIDnormals);
    glVertexAttribPointer( vNormal, 3, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0) );

}

void displayBunny( void ) {
    int size;

    glBindBuffer ( GL_ELEMENT_ARRAY_BUFFER, g_IBIDelements );
    glGetBufferParameteriv ( GL_ELEMENT_ARRAY_BUFFER, GL_BUFFER_SIZE, &size );
    glDrawElements ( GL_TRIANGLES, size/sizeof(GLushort), GL_UNSIGNED_SHORT, 0 );
}

void displayCube( void ) {
    glBindVertexArray(VAID_cube);
    glBindBuffer(GL_ARRAY_BUFFER,VBID_cube);
    glDrawArrays(GL_TRIANGLES,0,cbr_points.size());
}

我正在使用obj文件和顶点数组，所以我希望在一个场景中用不同的方法显示。

当我离散地使用这个功能时，它表现得很好，但是当我使用像

时

displayBunny();
displayCube();

它出错了。我必须只选择一种方法来显示基元？

Answer 1

glBindVertexArray(VAID_cube);

displayBunny中似乎忽略了其中一个。

此外，GL_ELEMENT_ARRAY_BUFFER是VAO状态的部分。每次渲染对象时都不应该重新绑定它。只需绑定VAO。