c++ - glvertexpointer std::vector, struct memory opengl

Question

我使用结构

struct Vertex
{
  float pos[3];
  float tex[2]  = {0, 0};
  float norm[3] = {0, 0, 0};
  int index_mtl;
};

我用 vector

std::vector<Vertex> verts;

如何将“glvertexpointer”用于我的结构 vector 。

我想用那个函数画图。最后我没有成功。

void Obj_render::DrawObject()
{
    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(3, GL_FLOAT, 0, verts.data()->pos);

    glDrawArrays(GL_TRIANGLES,0,3);
    // deactivate vertex arrays after drawing
    glDisableClientState(GL_VERTEX_ARRAY);

}

Answer 1

如果您使用这样的 struct，您的顶点不再紧密排列，您需要指定步幅:

glEnableClientState( GL_VERTEX_ARRAY );
glVertexPointer( 3, GL_FLOAT, sizeof( Vertex ), &verts[0].pos );
glDrawArrays( GL_TRIANGLES, 0, 3 );
glDisableClientState(GL_VERTEX_ARRAY);

像这样:

#include <GL/glut.h>
#include <vector>

struct Vertex
{
    float pos[3];
    float tex[2];
    float norm[3];
    int index_mtl;
};

std::vector< Vertex > verts;
void display()
{
    glClear( GL_COLOR_BUFFER_BIT );

    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();
    glOrtho( -2, 2, -2, 2, -1, 1 );

    glMatrixMode( GL_MODELVIEW );
    glLoadIdentity();

    glColor3ub( 255, 0, 0 );

    glEnableClientState( GL_VERTEX_ARRAY );
    glVertexPointer( 3, GL_FLOAT, sizeof( Vertex ), &verts[0].pos );
    glDrawArrays( GL_TRIANGLES, 0, 3 );
    glDisableClientState(GL_VERTEX_ARRAY);

    glutSwapBuffers();
}

int main( int argc, char **argv )
{
    Vertex tmp;
    tmp.pos[0] = 0;
    tmp.pos[1] = 0;
    tmp.pos[2] = 0;
    verts.push_back( tmp );
    tmp.pos[0] = 1;
    tmp.pos[1] = 0;
    tmp.pos[2] = 0;
    verts.push_back( tmp );
    tmp.pos[0] = 1;
    tmp.pos[1] = 1;
    tmp.pos[2] = 0;
    verts.push_back( tmp );

    glutInit( &argc, argv );
    glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE );
    glutInitWindowSize( 640, 480 );
    glutCreateWindow( "GLUT" );
    glutDisplayFunc( display );
    glutMainLoop();
    return 0;
}