text: #include <assert.h>
  #include <EGL/egl.h>
  #include <EGL/eglext.h>
  #include <gbm.h>
  #include <stdbool.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <wayland-util.h>
  #include <wlr/render/egl.h>
  #include <wlr/render/gles2.h>
  #include <wlr/render/wlr_renderer.h>
  #include <wlr/types/wlr_matrix.h>
  #include <wlr/util/log.h>
  #include "backend/drm/drm.h"
  #include "glapi.h"
  
  bool init_drm_renderer(struct wlr_drm_backend *drm,
  		struct wlr_drm_renderer *renderer, wlr_renderer_create_func_t create_renderer_func) {
  	renderer->gbm = gbm_create_device(drm->fd);
  	if (!renderer->gbm) {
  		wlr_log(WLR_ERROR, "Failed to create GBM device");
  		return false;
  	}
  
  	if (!create_renderer_func) {
  		create_renderer_func = wlr_renderer_autocreate;
  	}
  
  	static EGLint config_attribs[] = {
  		EGL_RED_SIZE, 1,
  		EGL_GREEN_SIZE, 1,
  		EGL_BLUE_SIZE, 1,
  		EGL_ALPHA_SIZE, 1,
  		EGL_NONE,
  	};
  
  	renderer->gbm_format = GBM_FORMAT_ARGB8888;
  	renderer->wlr_rend = create_renderer_func(&renderer->egl,
  		EGL_PLATFORM_GBM_MESA, renderer->gbm,
  		config_attribs, renderer->gbm_format);
  	if (!renderer->wlr_rend) {
  		wlr_log(WLR_ERROR, "Failed to create EGL/WLR renderer");
  		goto error_gbm;
  	}
  
  	renderer->fd = drm->fd;
  	return true;
  
  error_gbm:
  	gbm_device_destroy(renderer->gbm);
  	return false;
  }
  
  void finish_drm_renderer(struct wlr_drm_renderer *renderer) {
  	if (!renderer) {
  		return;
  	}
  
  	wlr_renderer_destroy(renderer->wlr_rend);
  	wlr_egl_finish(&renderer->egl);
  	gbm_device_destroy(renderer->gbm);
  }
  
  bool init_drm_surface(struct wlr_drm_surface *surf,
  		struct wlr_drm_renderer *renderer, uint32_t width, uint32_t height,
  		uint32_t format, uint32_t flags) {
  	if (surf->width == width && surf->height == height) {
  		return true;
  	}
  
  	surf->renderer = renderer;
  	surf->width = width;
  	surf->height = height;
  
  	if (surf->gbm) {
  		if (surf->front) {
  			gbm_surface_release_buffer(surf->gbm, surf->front);
  			surf->front = NULL;
  		}
  		if (surf->back) {
  			gbm_surface_release_buffer(surf->gbm, surf->back);
  			surf->back = NULL;
  		}
  		gbm_surface_destroy(surf->gbm);
  	}
  	wlr_egl_destroy_surface(&surf->renderer->egl, surf->egl);
  
  	surf->gbm = gbm_surface_create(renderer->gbm, width, height,
  		format, GBM_BO_USE_RENDERING | flags);
  	if (!surf->gbm) {
  		wlr_log_errno(WLR_ERROR, "Failed to create GBM surface");
  		goto error_zero;
  	}
  
  	surf->egl = wlr_egl_create_surface(&renderer->egl, surf->gbm);
  	if (surf->egl == EGL_NO_SURFACE) {
  		wlr_log(WLR_ERROR, "Failed to create EGL surface");
  		goto error_gbm;
  	}
  
  	return true;
  
  error_gbm:
  	gbm_surface_destroy(surf->gbm);
  error_zero:
  	memset(surf, 0, sizeof(*surf));
  	return false;
  }
  
  void finish_drm_surface(struct wlr_drm_surface *surf) {
  	if (!surf || !surf->renderer) {
  		return;
  	}
  
  	if (surf->front) {
  		gbm_surface_release_buffer(surf->gbm, surf->front);
  	}
  	if (surf->back) {
  		gbm_surface_release_buffer(surf->gbm, surf->back);
  	}
  
  	wlr_egl_destroy_surface(&surf->renderer->egl, surf->egl);
  	if (surf->gbm) {
  		gbm_surface_destroy(surf->gbm);
  	}
  
  	memset(surf, 0, sizeof(*surf));
  }
  
  bool make_drm_surface_current(struct wlr_drm_surface *surf,
  		int *buffer_damage) {
  	return wlr_egl_make_current(&surf->renderer->egl, surf->egl, buffer_damage);
  }
  
  struct gbm_bo *swap_drm_surface_buffers(struct wlr_drm_surface *surf,
  		pixman_region32_t *damage) {
  	if (surf->front) {
  		gbm_surface_release_buffer(surf->gbm, surf->front);
  	}
  
  	wlr_egl_swap_buffers(&surf->renderer->egl, surf->egl, damage);
  
  	surf->front = surf->back;
  	surf->back = gbm_surface_lock_front_buffer(surf->gbm);
  	return surf->back;
  }
  
  struct gbm_bo *get_drm_surface_front(struct wlr_drm_surface *surf) {
  	if (surf->front) {
  		return surf->front;
  	}
  
  	make_drm_surface_current(surf, NULL);
  	struct wlr_renderer *renderer = surf->renderer->wlr_rend;
  	wlr_renderer_begin(renderer, surf->width, surf->height);
  	wlr_renderer_clear(renderer, (float[]){ 0.0, 0.0, 0.0, 1.0 });
  	wlr_renderer_end(renderer);
  	return swap_drm_surface_buffers(surf, NULL);
  }
  
  void post_drm_surface(struct wlr_drm_surface *surf) {
  	if (surf->front) {
  		gbm_surface_release_buffer(surf->gbm, surf->front);
  		surf->front = NULL;
  	}
  }
  
  bool export_drm_bo(struct gbm_bo *bo, struct wlr_dmabuf_attributes *attribs) {
  	memset(attribs, 0, sizeof(struct wlr_dmabuf_attributes));
  
  	attribs->n_planes = gbm_bo_get_plane_count(bo);
  	if (attribs->n_planes > WLR_DMABUF_MAX_PLANES) {
  		return false;
  	}
  
  	attribs->width = gbm_bo_get_width(bo);
  	attribs->height = gbm_bo_get_height(bo);
  	attribs->format = gbm_bo_get_format(bo);
  	attribs->modifier = gbm_bo_get_modifier(bo);
  
  	for (int i = 0; i < attribs->n_planes; ++i) {
  		attribs->offset[i] = gbm_bo_get_offset(bo, i);
  		attribs->stride[i] = gbm_bo_get_stride_for_plane(bo, i);
  		attribs->fd[i] = gbm_bo_get_fd(bo);
  		if (attribs->fd[i] < 0) {
  			for (int j = 0; j < i; ++j) {
  				close(attribs->fd[j]);
  			}
  			return false;
  		}
  	}
  
  	return true;
  }
  
  static void free_tex(struct gbm_bo *bo, void *data) {
  	struct wlr_texture *tex = data;
  	wlr_texture_destroy(tex);
  }
  
  static struct wlr_texture *get_tex_for_bo(struct wlr_drm_renderer *renderer,
  		struct gbm_bo *bo) {
  	struct wlr_texture *tex = gbm_bo_get_user_data(bo);
  	if (tex) {
  		return tex;
  	}
  
  	struct wlr_dmabuf_attributes attribs;
  	if (!export_drm_bo(bo, &attribs)) {
  		return NULL;
  	}
  
  	tex = wlr_texture_from_dmabuf(renderer->wlr_rend, &attribs);
  	if (tex) {
  		gbm_bo_set_user_data(bo, tex, free_tex);
  	}
  
  	return tex;
  }
  
  struct gbm_bo *copy_drm_surface_mgpu(struct wlr_drm_surface *dest,
  		struct gbm_bo *src) {
  	make_drm_surface_current(dest, NULL);
  
  	struct wlr_texture *tex = get_tex_for_bo(dest->renderer, src);
  	assert(tex);
  
  	float mat[9];
  	wlr_matrix_projection(mat, 1, 1, WL_OUTPUT_TRANSFORM_NORMAL);
  
  	struct wlr_renderer *renderer = dest->renderer->wlr_rend;
  	wlr_renderer_begin(renderer, dest->width, dest->height);
  	wlr_renderer_clear(renderer, (float[]){ 0.0, 0.0, 0.0, 1.0 });
  	wlr_render_texture_with_matrix(renderer, tex, mat, 1.0f);
  	wlr_renderer_end(renderer);
  
  	return swap_drm_surface_buffers(dest, NULL);
  }
  
  bool init_drm_plane_surfaces(struct wlr_drm_plane *plane,
  		struct wlr_drm_backend *drm, int32_t width, uint32_t height,
  		uint32_t format) {
  	if (!drm->parent) {
  		return init_drm_surface(&plane->surf, &drm->renderer, width, height,
  			format, GBM_BO_USE_SCANOUT);
  	}
  
  	if (!init_drm_surface(&plane->surf, &drm->parent->renderer,
  			width, height, format, GBM_BO_USE_LINEAR)) {
  		return false;
  	}
  
  	if (!init_drm_surface(&plane->mgpu_surf, &drm->renderer,
  			width, height, format, GBM_BO_USE_SCANOUT)) {
  		finish_drm_surface(&plane->surf);
  		return false;
  	}
  
  	return true;
  }
  