MapLibreParticleLab/common/headless_view.cpp

#include "headless_view.hpp"
#include "headless_display.hpp"

#include <stdexcept>
#include <sstream>
#include <string>

#if MBGL_USE_GLX
typedef GLXContext (*glXCreateContextAttribsARBProc)(Display *, GLXFBConfig, GLXContext, Bool, const int *);
static glXCreateContextAttribsARBProc glXCreateContextAttribsARB = nullptr;
#endif

namespace mbgl {

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

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

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

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

#if MBGL_USE_GLX
    if (glXCreateContextAttribsARB == nullptr) {
        glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc)glXGetProcAddressARB((const GLubyte *)"glXCreateContextAttribsARB");
    }
    if (glXCreateContextAttribsARB == nullptr) {
        throw std::runtime_error("Cannot find glXCreateContextAttribsARB");
    }

    x_display = display_->x_display;
    fb_configs = display_->fb_configs;


    int attributes[] = {
        GLX_CONTEXT_MAJOR_VERSION_ARB, 2,
        GLX_CONTEXT_MINOR_VERSION_ARB, 1,
        GLX_CONTEXT_FLAGS_ARB, GLX_CONTEXT_DEBUG_BIT_ARB,
        GLX_CONTEXT_PROFILE_MASK_ARB, GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB,
        None
    };
    gl_context = glXCreateContextAttribsARB(x_display, fb_configs[0], 0, True, attributes);
    if (gl_context == nullptr) {
        throw std::runtime_error("Error creating GL context object");
    }

#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_;

#if MBGL_USE_CGL
    make_active();

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

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

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

    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_RENDERBUFFER_EXT, fbo_color);
    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER_EXT, fbo_depth_stencil);

    GLenum status = 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();
#endif

#if MBGL_USE_GLX
    int attributes[] = {
        GLX_PBUFFER_WIDTH, w,
        GLX_PBUFFER_HEIGHT, h,
        None
    };
    glx_pbuffer = glXCreatePbuffer(x_display, fb_configs[0], attributes);
#endif
}

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

    std::unique_ptr<uint32_t[]> pixels(new uint32_t[w * h]);

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

    return pixels;
}

void HeadlessView::clear_buffers() {
#if MBGL_USE_CGL
    make_active();

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

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

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

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

    make_inactive();
#endif

#if MBGL_USE_GLX
    make_inactive();

    if (glx_pbuffer) {
        glXDestroyPbuffer(x_display, glx_pbuffer);
        glx_pbuffer = 0;
    }
#endif
}

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

#if MBGL_USE_CGL
    CGLDestroyContext(gl_context);
#endif

#if MBGL_USE_GLX
    glXDestroyContext(x_display, gl_context);
#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(gl_context);
    if (error) {
        throw std::runtime_error("Switching OpenGL context failed\n");
    }
#endif

#if MBGL_USE_GLX
    if (!glXMakeContextCurrent(x_display, glx_pbuffer, glx_pbuffer, gl_context)) {
        throw std::runtime_error("Switching OpenGL context failed\n");
    }
#endif
}

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

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

void HeadlessView::swap() {}

unsigned int HeadlessView::root_fbo() {
#if MBGL_USE_CGL
    return fbo;
#endif

    return 0;
}

}