MapLibreParticleLab/platform/default/headless_view.cpp

#include <mbgl/platform/default/headless_view.hpp>
#include <mbgl/platform/default/headless_display.hpp>

#include <mbgl/util/std.hpp>

#include <stdexcept>
#include <sstream>
#include <string>
#include <cstring>
#include <cassert>

#if MBGL_USE_GLX
#ifdef GLX_ARB_create_context
static PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB = nullptr;
#endif
#endif

#ifdef MBGL_USE_CGL
#include <CoreFoundation/CoreFoundation.h>

typedef void (* CGLProc)(void);
CGLProc CGLGetProcAddress(const char *proc) {
    static CFBundleRef framework = nullptr;
    if (!framework) {
        framework = CFBundleGetBundleWithIdentifier(CFSTR("com.apple.opengl"));
        if (!framework) {
            throw std::runtime_error("Failed to load OpenGL framework.");
        }
    }

    CFStringRef name = CFStringCreateWithCString(kCFAllocatorDefault, proc, kCFStringEncodingASCII);
    CGLProc symbol = (CGLProc)CFBundleGetFunctionPointerForName(framework, name);
    CFRelease(name);
    return symbol;
}
#endif

namespace mbgl {


HeadlessView::HeadlessView()
    : display_(std::make_shared<HeadlessDisplay>()) {
    createContext();
    loadExtensions();
}

HeadlessView::HeadlessView(std::shared_ptr<HeadlessDisplay> display)
    : display_(display) {
    createContext();
    loadExtensions();
}

void HeadlessView::loadExtensions() {
    make_active();
    const std::string extensions = (char *)MBGL_CHECK_ERROR(glGetString(GL_EXTENSIONS));

#ifdef MBGL_USE_CGL
    if (extensions.find("GL_APPLE_vertex_array_object") != std::string::npos) {
        gl::BindVertexArray = (gl::PFNGLBINDVERTEXARRAYPROC)CGLGetProcAddress("glBindVertexArrayAPPLE");
        gl::DeleteVertexArrays = (gl::PFNGLDELETEVERTEXARRAYSPROC)CGLGetProcAddress("glDeleteVertexArraysAPPLE");
        gl::GenVertexArrays = (gl::PFNGLGENVERTEXARRAYSPROC)CGLGetProcAddress("glGenVertexArraysAPPLE");
        gl::IsVertexArray = (gl::PFNGLISVERTEXARRAYPROC)CGLGetProcAddress("glIsVertexArrayAPPLE");
        assert(gl::BindVertexArray != nullptr);
        assert(gl::DeleteVertexArrays != nullptr);
        assert(gl::GenVertexArrays != nullptr);
        assert(gl::IsVertexArray != nullptr);
    }
#endif
#ifdef MBGL_USE_GLX
    if (extensions.find("GL_ARB_vertex_array_object") != std::string::npos) {
        gl::BindVertexArray = (gl::PFNGLBINDVERTEXARRAYPROC)glXGetProcAddress((const GLubyte *)"glBindVertexArray");
        gl::DeleteVertexArrays = (gl::PFNGLDELETEVERTEXARRAYSPROC)glXGetProcAddress((const GLubyte *)"glDeleteVertexArrays");
        gl::GenVertexArrays = (gl::PFNGLGENVERTEXARRAYSPROC)glXGetProcAddress((const GLubyte *)"glGenVertexArrays");
        gl::IsVertexArray = (gl::PFNGLISVERTEXARRAYPROC)glXGetProcAddress((const GLubyte *)"glIsVertexArray");
        assert(gl::BindVertexArray != nullptr);
        assert(gl::DeleteVertexArrays != nullptr);
        assert(gl::GenVertexArrays != nullptr);
        assert(gl::IsVertexArray != nullptr);
    }
#endif

    make_inactive();
}


#if MBGL_USE_GLX
#ifdef GLX_ARB_create_context

// These are all of the OpenGL Core profile version that we know about.
struct core_profile_version { int major, minor; };
static const core_profile_version coreProfileVersions[] = {
    {4, 5},
    {4, 4},
    {4, 3},
    {4, 2},
    {4, 1},
    {4, 0},
    {3, 3},
    {3, 2},
    {3, 1},
    {3, 0},
    {0, 0},
};

GLXContext createCoreProfile(Display *dpy, GLXFBConfig fbconfig) {
    static bool contextCreationFailed = false;
    GLXContext ctx = 0;

    // Set the Error Handler to avoid crashing the program when the context creation fails.
    // It is expected that some context creation attempts fail, e.g. because the OpenGL
    // implementation does not support the version we're requesting.
    int (*previousErrorHandler)(Display *, XErrorEvent *) = XSetErrorHandler([](Display *, XErrorEvent *) {
        contextCreationFailed = true;
        return 0;
    });

    // Try to create core profiles from the highest known version on down.
    for (int i = 0; !ctx && coreProfileVersions[i].major; i++) {
        contextCreationFailed = false;
        const int contextFlags[] = {
            GLX_CONTEXT_MAJOR_VERSION_ARB, coreProfileVersions[i].major,
            GLX_CONTEXT_MINOR_VERSION_ARB, coreProfileVersions[i].minor,
            0
        };
        ctx = glXCreateContextAttribsARB(dpy, fbconfig, 0, True, contextFlags);
        if (contextCreationFailed) {
            ctx = 0;
        }
    }

    // Restore the old error handler.
    XSetErrorHandler(previousErrorHandler);
    return ctx;
}
#endif
#endif

void HeadlessView::createContext() {
#if MBGL_USE_CGL
    CGLError error = CGLCreateContext(display_->pixelFormat, NULL, &glContext);
    if (error != kCGLNoError) {
        throw std::runtime_error(std::string("Error creating GL context object:") + CGLErrorString(error) + "\n");
    }

    error = CGLEnable(glContext, kCGLCEMPEngine);
    if (error != kCGLNoError) {
        throw std::runtime_error(std::string("Error enabling OpenGL multithreading:") + CGLErrorString(error) + "\n");
    }
#endif

#if MBGL_USE_GLX
#ifdef GLX_ARB_create_context
    if (glXCreateContextAttribsARB == nullptr) {
        glXCreateContextAttribsARB = (PFNGLXCREATECONTEXTATTRIBSARBPROC)glXGetProcAddressARB((const GLubyte *)"glXCreateContextAttribsARB");
    }
#endif

    xDisplay = display_->xDisplay;
    fbConfigs = display_->fbConfigs;

#ifdef GLX_ARB_create_context
    if (glXCreateContextAttribsARB) {
        // Try to create a core profile context.
        glContext = createCoreProfile(xDisplay, fbConfigs[0]);
    }
#endif

    if (!glContext) {
        // Try to create a legacy context
        glContext = glXCreateNewContext(xDisplay, fbConfigs[0], GLX_RGBA_TYPE, 0, True);
        if (glContext) {
            if (!glXIsDirect(xDisplay, glContext)) {
                glXDestroyContext(xDisplay, glContext);
                glContext = 0;
            }
        }
    }

    if (glContext == 0) {
        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,
        0
    };
    glxPbuffer = glXCreatePbuffer(xDisplay, fbConfigs[0], pbufferAttributes);
#endif
}

void HeadlessView::resize(uint16_t width, uint16_t height, float pixelRatio) {
    clear_buffers();

    width_ = width;
    height_ = height;
    pixelRatio_ = pixelRatio;

    const unsigned int w = width_ * pixelRatio_;
    const unsigned int h = height_ * pixelRatio_;

    make_active();

    // Create depth/stencil buffer
    MBGL_CHECK_ERROR(glGenRenderbuffersEXT(1, &fboDepthStencil));
    MBGL_CHECK_ERROR(glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fboDepthStencil));
    MBGL_CHECK_ERROR(glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH24_STENCIL8_EXT, w, h));
    MBGL_CHECK_ERROR(glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0));

    MBGL_CHECK_ERROR(glGenRenderbuffersEXT(1, &fboColor));
    MBGL_CHECK_ERROR(glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fboColor));
    MBGL_CHECK_ERROR(glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_RGBA8, w, h));
    MBGL_CHECK_ERROR(glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0));

    MBGL_CHECK_ERROR(glGenFramebuffersEXT(1, &fbo));
    MBGL_CHECK_ERROR(glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo));

    MBGL_CHECK_ERROR(glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_RENDERBUFFER_EXT, fboColor));
    MBGL_CHECK_ERROR(glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER_EXT, fboDepthStencil));

    GLenum status = MBGL_CHECK_ERROR(glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT));

    if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
        std::stringstream error("Couldn't create framebuffer: ");
        switch (status) {
            case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT: (error << "incomplete attachment.\n"); break;
            case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT_EXT: error << "incomplete missing attachment.\n"; break;
            case GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT: error << "incomplete dimensions.\n"; break;
            case GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT: error << "incomplete formats.\n"; break;
            case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT: error << "incomplete draw buffer.\n"; break;
            case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT: error << "incomplete read buffer.\n"; break;
            case GL_FRAMEBUFFER_UNSUPPORTED: error << "unsupported.\n"; break;
            default: error << "other\n"; break;
        }
        throw std::runtime_error(error.str());
    }

    make_inactive();
}

std::unique_ptr<uint32_t[]> HeadlessView::readPixels() {
    const unsigned int w = width_ * pixelRatio_;
    const unsigned int h = height_ * pixelRatio_;

    auto pixels = util::make_unique<uint32_t[]>(w * h);

    make_active();
    MBGL_CHECK_ERROR(glReadPixels(0, 0, width_, height_, GL_RGBA, GL_UNSIGNED_BYTE, pixels.get()));
    make_inactive();

    const int stride = w * 4;
    auto tmp = util::make_unique<char[]>(stride);
    char *rgba = reinterpret_cast<char *>(pixels.get());
    for (int i = 0, j = height_ - 1; i < j; i++, j--) {
        std::memcpy(tmp.get(), rgba + i * stride, stride);
        std::memcpy(rgba + i * stride, rgba + j * stride, stride);
        std::memcpy(rgba + j * stride, tmp.get(), stride);
    }

    return pixels;
}

void HeadlessView::clear_buffers() {
    make_active();

    MBGL_CHECK_ERROR(glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0));

    if (fbo) {
        MBGL_CHECK_ERROR(glDeleteFramebuffersEXT(1, &fbo));
        fbo = 0;
    }

    if (fboColor) {
        MBGL_CHECK_ERROR(glDeleteTextures(1, &fboColor));
        fboColor = 0;
    }

    if (fboDepthStencil) {
        MBGL_CHECK_ERROR(glDeleteRenderbuffersEXT(1, &fboDepthStencil));
        fboDepthStencil = 0;
    }

    make_inactive();
}

HeadlessView::~HeadlessView() {
    clear_buffers();

#if MBGL_USE_CGL
    CGLDestroyContext(glContext);
#endif

#if MBGL_USE_GLX
    if (glxPbuffer) {
        glXDestroyPbuffer(xDisplay, glxPbuffer);
        glxPbuffer = 0;
    }

    glXDestroyContext(xDisplay, glContext);
#endif
}

void HeadlessView::notify() {
    // no-op
}

void HeadlessView::notify_map_change(mbgl::MapChange /*change*/, mbgl::timestamp /*delay*/) {
    // no-op
}

void HeadlessView::make_active() {
#if MBGL_USE_CGL
    CGLError error = CGLSetCurrentContext(glContext);
    if (error != kCGLNoError) {
        throw std::runtime_error(std::string("Switching OpenGL context failed:") + CGLErrorString(error) + "\n");
    }
#endif

#if MBGL_USE_GLX
    if (!glXMakeContextCurrent(xDisplay, glxPbuffer, glxPbuffer, glContext)) {
        throw std::runtime_error("Switching OpenGL context failed.\n");
    }
#endif
}

void HeadlessView::make_inactive() {
#if MBGL_USE_CGL
    CGLError error = CGLSetCurrentContext(nullptr);
    if (error != kCGLNoError) {
        throw std::runtime_error(std::string("Removing OpenGL context failed:") + CGLErrorString(error) + "\n");
    }
#endif

#if MBGL_USE_GLX
    if (!glXMakeContextCurrent(xDisplay, 0, 0, nullptr)) {
        throw std::runtime_error("Removing OpenGL context failed.\n");
    }
#endif
}

void HeadlessView::swap() {}

}