大家好，感谢您花时间阅读这篇文章！
我正在编写一款使用GTK2/3 + OpenGL开发的程序，我已经成功地运行了两个版本：
- (a) GTK+2 + GtkGlext扩展 -> 运行得非常好！
- (b) GTK+3 + LibX11 -> 运行良好！
除了(a)中的渲染速度明显快于(b)，其他都看起来很正常...我不知道原因在哪里。以下是一些创建OpenGL上下文所使用的代码段示例：
(a)
// To create the context, and the associated GtkWidget GdkGLConfig * glconfig = gdk_gl_config_new_by_mode (GDK_GL_MODE_RGBA | GDK_GL_MODE_DEPTH | GDK_GL_MODE_DOUBLE); GtkWidget * drawing_area = gtk_drawing_area_new (); gtk_widget_set_gl_capability (drawing_area, glconfig, NULL, TRUE, GDK_GL_RGBA_TYPE); g_signal_connect (G_OBJECT (drawing_area), "expose-event", G_CALLBACK (on_expose), data); // And later on to draw using the OpenGL context: gboolean on_expose (GtkWidget * widg, GdkEvent * event, gpointer data) { GdkGLContext * glcontext = gtk_widget_get_gl_context (widg); GdkGLDrawable * gldrawable = gtk_widget_get_gl_drawable (widg); if (gdk_gl_drawable_gl_begin (gldrawable, glcontext)) { // OpenGL instructions to draw here ! gdk_gl_drawable_swap_buffers (view -> gldrawable); gdk_gl_drawable_gl_end (view -> gldrawable); } return TRUE; }(b)
// To create the GtkWidget GtkWidget * drawing_area = gtk_drawing_area_new (); // Next line is required to avoid background flickering gtk_widget_set_double_buffered (drawing_area, FALSE); g_signal_connect (G_OBJECT (drawing_area), "realize", G_CALLBACK(on_realize), data); g_signal_connect (G_OBJECT (drawing_area), "draw", G_CALLBACK(on_expose), data); // To create the OpenGL context GLXContext glcontext; G_MODULE_EXPORT void on_realize (GtkWidget * widg, gpointer data) { GdkWindow * xwin = gtk_widget_get_window (widg); GLint attr_list[] = {GLX_DOUBLEBUFFER, GLX_RGBA, GLX_DEPTH_SIZE, 16, GLX_RED_SIZE, 8, GLX_GREEN_SIZE, 8, GLX_BLUE_SIZE, 8, None}; XVisualInfo * visualinfo = glXChooseVisual (GDK_WINDOW_XDISPLAY (xwin), gdk_screen_get_number (gdk_window_get_screen (xwin)), attr_list); glcontext = glXCreateContext (GDK_WINDOW_XDISPLAY (xwin), visualinfo, NULL, TRUE); xfree (visualinfo); } // To Draw using the OpenGL context G_MODULE_EXPORT gboolean on_expose (GtkWidget * widg, cairo_t * cr, gpointer data) { GdkWindow * win = gtk_widget_get_window (widg); if (glXMakeCurrent (GDK_WINDOW_XDISPLAY (xwin), GDK_WINDOW_XID (xwin), glcontext)) { // OpenGL instructions to draw here ! glXSwapBuffers (GDK_WINDOW_XDISPLAY (win), GDK_WINDOW_XID (win)); } return TRUE; }
gtk_widget_set_double_buffered (drawing_area, FALSE);
渲染出了问题，我无能为力... 或者OpenGL上下文之间存在差异，这可能解释我注意到的行为。如果我按照这个方向进行跟进，我需要尽可能详细地比较两个上下文...到目前为止，我选择了似乎是获取信息的最常见方式：
OpenGL Version : 3.0 Mesa 12.0.3
OpenGL Vendor : nouveau
OpenGL Renderer : Gallium 0.4 on NVCF
OpenGL Shading Version : 1.30
Color Bits (R,G,B,A) : 8, 8, 8, 0
Depth Bits : 24
Stencil Bits : 0
Max. Lights Allowed : 8
Max. Texture Size : 16384
Max. Clipping Planes : 8
Max. Modelview Matrix Stacks : 32
Max. Projection Matrix Stacks : 32
Max. Attribute Stacks : 16
Max. Texture Stacks : 10
Total number of OpenGL Extensions : 227
Extensions list:
N°1 : GL_AMD_conservative_depth
N°2 : GL_AMD_draw_buffers_blend
...
但两种上下文返回的信息完全相同...
感谢您已经到达那里...现在我的问题是：
有没有办法输出尽可能多的关于OpenGL上下文的信息，如何？
我欢迎您对我正在做的事情提出任何其他建议！
S.
PS：我正在使用GTK3的GtkGLArea小部件，但正如这里所述，我还没有到达那里。
[编辑]一些OpenGL指令：
// OpenGL instructions to draw here !
glLoadIdentity ();
glPushMatrix ();
// d is the depth ... calculated somewhere else
glTranslated (0.0, 0.0, -d);
// Skipping the rotation part for clarity, I am using a quaternion
rotate_camera ();
// r, g, b and a are GLFloat values
glClearColor (r,g,b,a);
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
glDisable (GL_LIGHTING);
int i;
// nbds is the number of chemical bonds
GLfloat * lineVertices;
// This is "roughly" what I do to draw chemical bonds, to give you an idea
for (i=0; i<nbds;i++)
{
// get_bonds (i) gives backs a 6 float array
lineVertices = get_bonds(i);
glPushMatrix();
glLineWidth (1.0);
glEnableClientState (GL_VERTEX_ARRAY);
glVertexPointer (3, GL_FLOAT, 0, lineVertices);
glDrawArrays (GL_LINES, 0, 2);
glDisableClientState (GL_VERTEX_ARRAY);
glPopMatrix();
}
glEnable (GL_LIGHTING);
[/EDIT]
LIBGL_ALWAYS_INDIRECT=1运行第一个应用程序，看看性能是否同样糟糕。 - thokra