1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
|
#include <mbgl/gl/headless_backend.hpp>
#include <mbgl/util/logging.hpp>
#include <cassert>
#include <GL/glx.h>
namespace mbgl {
// This class provides a singleton that contains information about the configuration used for
// instantiating new headless rendering contexts.
class GLXDisplayConfig {
private:
// Key for singleton construction.
struct Key { explicit Key() = default; };
public:
GLXDisplayConfig(Key) {
if (!XInitThreads()) {
throw std::runtime_error("Failed to XInitThreads.");
}
xDisplay = XOpenDisplay(nullptr);
if (xDisplay == nullptr) {
throw std::runtime_error("Failed to open X display.");
}
const auto* extensions = reinterpret_cast<const char*>(
glXQueryServerString(xDisplay, DefaultScreen(xDisplay), GLX_EXTENSIONS));
if (!extensions) {
throw std::runtime_error("Cannot read GLX extensions.");
}
if (!strstr(extensions, "GLX_SGIX_fbconfig")) {
throw std::runtime_error("Extension GLX_SGIX_fbconfig was not found.");
}
if (!strstr(extensions, "GLX_SGIX_pbuffer")) {
throw std::runtime_error("Cannot find glXCreateContextAttribsARB.");
}
// We're creating a dummy pbuffer anyway that we're not using.
static int pixelFormat[] = { GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT, None };
int configs = 0;
fbConfigs = glXChooseFBConfig(xDisplay, DefaultScreen(xDisplay), pixelFormat, &configs);
if (fbConfigs == nullptr) {
throw std::runtime_error("Failed to glXChooseFBConfig.");
}
if (configs <= 0) {
throw std::runtime_error("No Framebuffer configurations.");
}
}
~GLXDisplayConfig() {
XFree(fbConfigs);
XCloseDisplay(xDisplay);
}
static std::shared_ptr<const GLXDisplayConfig> create() {
static std::weak_ptr<const GLXDisplayConfig> instance;
auto shared = instance.lock();
if (!shared) {
instance = shared = std::make_shared<GLXDisplayConfig>(Key{});
}
return shared;
}
public:
Display* xDisplay = nullptr;
GLXFBConfig* fbConfigs = nullptr;
};
struct GLXImpl : public HeadlessBackend::Impl {
GLXImpl() {
// Try to create a legacy context.
glContext = glXCreateNewContext(glxDisplay->xDisplay, glxDisplay->fbConfigs[0],
GLX_RGBA_TYPE, None, True);
if (glContext && !glXIsDirect(glxDisplay->xDisplay, glContext)) {
Log::Error(Event::OpenGL, "failed to create direct OpenGL Legacy context");
glXDestroyContext(glxDisplay->xDisplay, glContext);
glContext = nullptr;
}
if (glContext == nullptr) {
throw std::runtime_error("Error creating GL context object.");
}
// Create a dummy pbuffer. We will render to framebuffers anyway, but we need a pbuffer to
// activate the context.
int pbufferAttributes[] = { GLX_PBUFFER_WIDTH, 8, GLX_PBUFFER_HEIGHT, 8, None };
glxPbuffer =
glXCreatePbuffer(glxDisplay->xDisplay, glxDisplay->fbConfigs[0], pbufferAttributes);
}
~GLXImpl() final {
if (glxPbuffer) {
glXDestroyPbuffer(glxDisplay->xDisplay, glxPbuffer);
}
glXDestroyContext(glxDisplay->xDisplay, glContext);
}
void activateContext() final {
if (!glXMakeContextCurrent(glxDisplay->xDisplay, glxPbuffer, glxPbuffer, glContext)) {
throw std::runtime_error("Switching OpenGL context failed.\n");
}
}
void deactivateContext() final {
if (!glXMakeContextCurrent(glxDisplay->xDisplay, 0, 0, nullptr)) {
throw std::runtime_error("Removing OpenGL context failed.\n");
}
}
private:
const std::shared_ptr<const GLXDisplayConfig> glxDisplay = GLXDisplayConfig::create();
GLXContext glContext = nullptr;
GLXPbuffer glxPbuffer = 0;
};
gl::ProcAddress HeadlessBackend::initializeExtension(const char* name) {
return glXGetProcAddress(reinterpret_cast<const GLubyte*>(name));
}
void HeadlessBackend::createContext() {
assert(!hasContext());
impl = std::make_unique<GLXImpl>();
}
} // namespace mbgl
|
