学步园

以画xyz坐标轴为例，很多人会遇到用glcolor设置了颜色，但是直线画出来还是黑色或者白色的情况，这可能是因为没有打开GL_COLOR_MATERIAL，或者没有关闭GL_TEXTURE_2D

glEnable(GL_DEPTH_TEST);
    
    glLineWidth(3.0f); 
    glEnable(GL_COLOR_MATERIAL);
    
    float axes_length = 0.2;
    
    glEnableClientState(GL_VERTEX_ARRAY);
    glColor4f(1.0, 0, 0, 1);
    float linevertexs_x[6] = {0,0,0,axes_length,0,0};
    glVertexPointer(3,GL_FLOAT,0, linevertexs_x);
    glDrawArrays(GL_LINES,0, 2);
        
    glColor4f(0, 1.0, 0, 1);
    float linevertexs_y[6] = {0,0,0,0,axes_length,0};
    glVertexPointer(3,GL_FLOAT,0, linevertexs_y);
    glDrawArrays(GL_LINES,0, 2);
    
  
    glColor4f(0, 0, 1.0, 1);
    float linevertexs_z[6] = {0,0,0,0,0,axes_length};
    glVertexPointer(3,GL_FLOAT,0, linevertexs_z);
    glDrawArrays(GL_LINES,0, 2);
    
    //glColor4f(1, 1, 1, 1);

    glDisableClientState(GL_VERTEX_ARRAY);
    glDisable(GL_COLOR_MATERIAL);