Fix compilation error after rebase.

source/blender/blenkernel/BKE_node.h

@@ -1219,6 +1219,7 @@ void BKE_nodetree_remove_layer_n(struct bNodeTree *ntree, struct Scene *scene, i
 #define SH_NODE_COMBINE_COLOR 711
 #define SH_NODE_SEPARATE_COLOR 712
 #define SH_NODE_MIX 713
+#define SH_NODE_VIRTUAL_MONITOR 714
 
 /** \} */
 

source/blender/blenkernel/intern/camera.c

@@ -41,6 +41,8 @@
 
 #include "DEG_depsgraph_query.h"
 
+#include "GPU_viewport.h"
+
 #include "MEM_guardedalloc.h"
 
 #include "BLO_read_write.h"
@@ -83,10 +85,21 @@ static void camera_copy_data(Main *UNUSED(bmain), ID *id_dst, const ID *id_src,
 }
 
 /** Free (or release) any data used by this camera (does not free the camera itself). */
+static void camera_free_runtime_data(Camera *camera)
+{
+  if (camera->runtime.virtual_monitor_offscreen) {
+    GPU_offscreen_free(camera->runtime.virtual_monitor_offscreen);
+    camera->runtime.virtual_monitor_offscreen = NULL;
+  }
+  /* GPU texture is owned by the GPUOffscreen instance. */
+  camera->runtime.offscreen_color_texture = NULL;
+}
+
 static void camera_free_data(ID *id)
 {
   Camera *cam = (Camera *)id;
   BLI_freelistN(&cam->bg_images);
+  camera_free_runtime_data(cam);
 }
 
 static void camera_foreach_id(ID *id, LibraryForeachIDData *data)
@@ -137,6 +150,8 @@ static void camera_blend_read_data(BlendDataReader *reader, ID *id)
       bgpic->flag &= ~CAM_BGIMG_FLAG_OVERRIDE_LIBRARY_LOCAL;
     }
   }
+  ca->runtime.virtual_monitor_offscreen = NULL;
+  ca->runtime.offscreen_color_texture = NULL;
 }
 
 static void camera_blend_read_lib(BlendLibReader *reader, ID *id)

source/blender/blenkernel/intern/node.cc

@@ -4648,6 +4648,8 @@ static void registerShaderNodes()
   register_node_type_sh_tex_pointdensity();
   register_node_type_sh_tex_ies();
   register_node_type_sh_tex_white_noise();
+
+  register_node_type_sh_virtual_camera();
 }
 
 static void registerTextureNodes()

source/blender/draw/DRW_engine.h

@@ -99,6 +99,7 @@ void DRW_draw_render_loop_offscreen(struct Depsgraph *depsgraph,
                                     bool is_image_render,
                                     bool draw_background,
                                     bool do_color_management,
+                                    bool is_virtual_camera,
                                     struct GPUOffScreen *ofs,
                                     struct GPUViewport *viewport);
 void DRW_draw_render_loop_2d_ex(struct Depsgraph *depsgraph,

source/blender/draw/engines/eevee/eevee_materials.c

@@ -861,6 +861,12 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
               continue;
             }
 
+            /* Virtual cameras can only be used in the main scene. */
+            if (DRW_state_is_virtual_camera() &&
+                GPU_material_flag_get(gpumat_array[i], GPU_MATFLAG_VIRTUAL_MONITOR)) {
+              continue;
+            }
+
             /* Do not render surface if we are rendering a volume object
              * and do not have a surface closure. */
             if (use_volume_material &&

source/blender/draw/intern/DRW_render.h

@@ -885,6 +885,10 @@ bool DRW_state_is_scene_render(void);
  */
 bool DRW_state_is_opengl_render(void);
 bool DRW_state_is_playback(void);
+/**
+ * Whether we are rendering a virtual camera, false when rendering the main camera/viewport.
+ */
+bool DRW_state_is_virtual_camera(void);
 /**
  * Is the user navigating the region.
  */

source/blender/draw/intern/draw_manager.c

@@ -1807,6 +1807,7 @@ void DRW_draw_render_loop_offscreen(struct Depsgraph *depsgraph,
                                     const bool is_image_render,
                                     const bool draw_background,
                                     const bool do_color_management,
+                                    const bool is_virtual_camera,
                                     GPUOffScreen *ofs,
                                     GPUViewport *viewport)
 {
@@ -1830,6 +1831,7 @@ void DRW_draw_render_loop_offscreen(struct Depsgraph *depsgraph,
   drw_state_prepare_clean_for_draw(&DST);
   DST.options.is_image_render = is_image_render;
   DST.options.draw_background = draw_background;
+  DST.options.is_virtual_camera = is_virtual_camera;
   DRW_draw_render_loop_ex(depsgraph, engine_type, region, v3d, render_viewport, NULL);
 
   if (draw_background) {
@@ -2921,6 +2923,11 @@ bool DRW_state_is_opengl_render(void)
   return DST.options.is_image_render && !DST.options.is_scene_render;
 }
 
+bool DRW_state_is_virtual_camera(void)
+{
+  return DST.options.is_virtual_camera;
+}
+
 bool DRW_state_is_playback(void)
 {
   if (DST.draw_ctx.evil_C != NULL) {

source/blender/draw/intern/draw_manager.h

@@ -612,6 +612,7 @@ typedef struct DRWManager {
     uint is_depth : 1;
     uint is_image_render : 1;
     uint is_scene_render : 1;
+    uint is_virtual_camera : 1;
     uint draw_background : 1;
     uint draw_text : 1;
   } options;

source/blender/draw/intern/draw_manager_data.cc

@@ -1835,6 +1835,11 @@ void DRW_shgroup_add_material_resources(DRWShadingGroup *grp, GPUMaterial *mater
       DRW_shgroup_uniform_texture_ex(
           grp, tex->sampler_name, *tex->sky, eGPUSamplerState(tex->sampler_state));
     }
+    else if (tex->camera && tex->camera[0]) {
+      /* VirtualCamera */
+      DRW_shgroup_uniform_texture_ex(
+          grp, tex->sampler_name, *tex->camera, eGPUSamplerState(tex->sampler_state));
+    }
   }
 
   GPUUniformBuf *ubo = GPU_material_uniform_buffer_get(material);

source/blender/editors/include/ED_view3d_offscreen.h

@@ -39,6 +39,7 @@ void ED_view3d_draw_offscreen(struct Depsgraph *depsgraph,
                               const char *viewname,
                               bool do_color_management,
                               bool restore_rv3d_mats,
+                              bool is_virtual_camera,
                               struct GPUOffScreen *ofs,
                               struct GPUViewport *viewport);
 /**

source/blender/editors/space_node/drawnode.cc

@@ -432,6 +432,20 @@ static void node_shader_buts_tex_environment(uiLayout *layout, bContext *C, Poin
   node_buts_image_user(layout, C, &iuserptr, &imaptr, &iuserptr, false, true);
 }
 
+static void node_shader_buts_virtual_monitor(uiLayout *layout, bContext *C, PointerRNA *ptr)
+{
+  uiTemplateID(layout,
+               C,
+               ptr,
+               "camera",
+               nullptr,
+               nullptr,
+               nullptr,
+               UI_TEMPLATE_ID_FILTER_ALL,
+               false,
+               nullptr);
+}
+
 static void node_shader_buts_tex_environment_ex(uiLayout *layout, bContext *C, PointerRNA *ptr)
 {
   PointerRNA iuserptr = RNA_pointer_get(ptr, "image_user");
@@ -499,6 +513,9 @@ static void node_shader_set_butfunc(bNodeType *ntype)
       ntype->draw_buttons = node_shader_buts_tex_environment;
       ntype->draw_buttons_ex = node_shader_buts_tex_environment_ex;
       break;
+    case SH_NODE_VIRTUAL_MONITOR:
+      ntype->draw_buttons = node_shader_buts_virtual_monitor;
+      break;
     case SH_NODE_DISPLACEMENT:
     case SH_NODE_VECTOR_DISPLACEMENT:
       ntype->draw_buttons = node_shader_buts_displacement;

source/blender/editors/space_view3d/view3d_draw.cc

@@ -7,6 +7,7 @@
 
 #include <cmath>
 
+#include "BLI_float4x4.hh"
 #include "BLI_jitter_2d.h"
 #include "BLI_listbase.h"
 #include "BLI_math.h"
@@ -15,6 +16,7 @@
 #include "BLI_string.h"
 #include "BLI_string_utils.h"
 #include "BLI_threads.h"
+#include "BLI_vector.hh"
 
 #include "BKE_armature.h"
 #include "BKE_camera.h"
@@ -26,6 +28,7 @@
 #include "BKE_key.h"
 #include "BKE_layer.h"
 #include "BKE_main.h"
+#include "BKE_node.h"
 #include "BKE_object.h"
 #include "BKE_paint.h"
 #include "BKE_scene.h"
@@ -40,6 +43,7 @@
 #include "DNA_brush_types.h"
 #include "DNA_camera_types.h"
 #include "DNA_key_types.h"
+#include "DNA_material_types.h"
 #include "DNA_mesh_types.h"
 #include "DNA_object_types.h"
 #include "DNA_view3d_types.h"
@@ -61,6 +65,7 @@
 
 #include "GPU_batch.h"
 #include "GPU_batch_presets.h"
+#include "GPU_debug.h"
 #include "GPU_framebuffer.h"
 #include "GPU_immediate.h"
 #include "GPU_immediate_util.h"
@@ -87,6 +92,9 @@
 #include "view3d_intern.h" /* own include */
 
 using blender::float4;
+using blender::float4x4;
+using blender::int2;
+using blender::Vector;
 
 #define M_GOLDEN_RATIO_CONJUGATE 0.618033988749895f
 
@@ -1535,14 +1543,120 @@ void view3d_draw_region_info(const bContext *C, ARegion *region)
 /** \name Draw Viewport Contents
  * \{ */
 
+static void view3d_virtual_camera_update(
+    Scene *scene, Depsgraph *depsgraph, View3D *v3d, ARegion *region, Object *object)
+{
+  BLI_assert(object->type == OB_CAMERA);
+  int2 resolution(1920 / 2, 1080 / 2);
+
+  RegionView3D *old_rv3d = static_cast<RegionView3D *>(region->regiondata);
+  RegionView3D rv3d;
+  memcpy(&rv3d, old_rv3d, sizeof(RegionView3D));
+  region->regiondata = &rv3d;
+
+  Object *old_camera = v3d->camera;
+  v3d->camera = object;
+  rv3d.persp = RV3D_CAMOB;
+
+  Camera *camera = static_cast<Camera *>(object->data);
+  if (camera->runtime.virtual_monitor_offscreen == nullptr) {
+    camera->runtime.virtual_monitor_offscreen = GPU_offscreen_create(
+        UNPACK2(resolution), true, GPU_RGBA16F, nullptr);
+  }
+
+  float4x4 winmat;
+
+  // TODO: Multi view support?
+  CameraParams params;
+  BKE_camera_params_init(&params);
+  /* fallback for non camera objects */
+  params.clip_start = v3d->clip_start;
+  params.clip_end = v3d->clip_end;
+  BKE_camera_params_from_object(&params, object);
+  BKE_camera_params_compute_viewplane(&params, UNPACK2(resolution), scene->r.xasp, scene->r.yasp);
+  BKE_camera_params_compute_matrix(&params);
+  copy_m4_m4(winmat.ptr(), params.winmat);
+
+  GPUOffScreen *offscreen = camera->runtime.virtual_monitor_offscreen;
+
+  GPU_offscreen_bind(offscreen, true);
+  ED_view3d_draw_offscreen(depsgraph,
+                           scene,
+                           OB_MATERIAL,
+                           v3d,
+                           region,
+                           UNPACK2(resolution),
+                           nullptr,
+                           winmat.ptr(),
+                           false,
+                           true,
+                           nullptr,
+                           false,
+                           true,
+                           true,
+                           offscreen,
+                           nullptr);
+  GPU_offscreen_unbind(offscreen, true);
+  camera->runtime.offscreen_color_texture = GPU_offscreen_color_texture(
+      camera->runtime.virtual_monitor_offscreen);
+
+  v3d->camera = old_camera;
+  region->regiondata = old_rv3d;
+}
+
+static void view3d_draw_virtual_camera(Scene *scene,
+                                       Depsgraph *depsgraph,
+                                       View3D *v3d,
+                                       ARegion *region)
+{
+  /* TODO: Bad call! */
+  Main *bmain = DEG_get_bmain(depsgraph);
+
+  /* Collect all cameras in the scene that is used inside a virtual monitor. This should be
+   * optimized by a tagging system. There are far more materials then cameras in a typical scene.
+   */
+  Vector<Object *> virtual_cameras;
+  LISTBASE_FOREACH (Material *, material, &bmain->materials) {
+    if (!material->nodetree) {
+      continue;
+    }
+
+    LISTBASE_FOREACH (bNode *, node, &material->nodetree->nodes) {
+      if (node->type != SH_NODE_VIRTUAL_MONITOR) {
+        continue;
+      }
+      Object *ob = static_cast<Object *>(static_cast<void *>(node->id));
+      if (ob == nullptr || ob->type != OB_CAMERA) {
+        continue;
+      }
+      virtual_cameras.append(ob);
+    }
+  }
+
+  if (virtual_cameras.is_empty()) {
+    /* No cameras used as virtual monitor, so skip updating. */
+    return;
+  }
+
+  GPU_debug_group_begin("VirtualCameras");
+  for (Object *object : virtual_cameras) {
+    view3d_virtual_camera_update(scene, depsgraph, v3d, region, object);
+  }
+  GPU_debug_group_end();
+}
+
 static void view3d_draw_view(const bContext *C, ARegion *region)
 {
+  Scene *scene = CTX_data_scene(C);
+  Depsgraph *depsgraph = CTX_data_expect_evaluated_depsgraph(C);
+  View3D *v3d = CTX_wm_view3d(C);
+  view3d_draw_virtual_camera(scene, depsgraph, v3d, region);
   ED_view3d_draw_setup_view(CTX_wm_manager(C),
                             CTX_wm_window(C),
-                            CTX_data_expect_evaluated_depsgraph(C),
-                            CTX_data_scene(C),
+                            depsgraph,
+                            scene,
                             region,
-                            CTX_wm_view3d(C),
+                            v3d,
                             nullptr,
                             nullptr,
                             nullptr);
@@ -1640,6 +1754,7 @@ void ED_view3d_draw_offscreen(Depsgraph *depsgraph,
                               const char *viewname,
                               const bool do_color_management,
                               const bool restore_rv3d_mats,
+                              const bool is_virtual_camera,
                               GPUOffScreen *ofs,
                               GPUViewport *viewport)
 {
@@ -1715,6 +1830,7 @@ void ED_view3d_draw_offscreen(Depsgraph *depsgraph,
                                  is_image_render,
                                  draw_background,
                                  do_color_management,
+                                 is_virtual_camera,
                                  ofs,
                                  viewport);
   DRW_cache_free_old_subdiv();
@@ -1830,6 +1946,8 @@ void ED_view3d_draw_offscreen_simple(Depsgraph *depsgraph,
   /* Actually not used since we pass in the projection matrix. */
   v3d.lens = 0;
 
+  view3d_draw_virtual_camera(scene, depsgraph, &v3d, &ar);
+
   ED_view3d_draw_offscreen(depsgraph,
                            scene,
                            drawtype,
@@ -1844,6 +1962,7 @@ void ED_view3d_draw_offscreen_simple(Depsgraph *depsgraph,
                            viewname,
                            do_color_management,
                            true,
+                           false,
                            ofs,
                            viewport);
 }
@@ -1967,6 +2086,7 @@ ImBuf *ED_view3d_draw_offscreen_imbuf(Depsgraph *depsgraph,
                            viewname,
                            do_color_management,
                            restore_rv3d_mats,
+                           false,
                            ofs,
                            nullptr);
 

source/blender/gpu/CMakeLists.txt

@@ -449,6 +449,7 @@ set(GLSL_SRC
   shaders/material/gpu_shader_material_vector_rotate.glsl
   shaders/material/gpu_shader_material_velvet.glsl
   shaders/material/gpu_shader_material_vertex_color.glsl
+  shaders/material/gpu_shader_material_virtual_camera.glsl
   shaders/material/gpu_shader_material_volume_absorption.glsl
   shaders/material/gpu_shader_material_volume_principled.glsl
   shaders/material/gpu_shader_material_volume_scatter.glsl

source/blender/gpu/GPU_material.h

@@ -35,6 +35,7 @@ struct Material;
 struct Scene;
 struct bNode;
 struct bNodeTree;
+struct Camera;
 
 typedef struct GPUMaterial GPUMaterial;
 typedef struct GPUNode GPUNode;
@@ -82,6 +83,8 @@ typedef enum eGPUMaterialFlag {
   GPU_MATFLAG_OBJECT_INFO = (1 << 10),
   GPU_MATFLAG_AOV = (1 << 11),
 
+  GPU_MATFLAG_VIRTUAL_MONITOR = (1 << 12),
+
   GPU_MATFLAG_BARYCENTRIC = (1 << 20),
 
   /* Optimization to only add the branches of the principled shader that are necessary. */
@@ -178,6 +181,9 @@ GPUNodeLink *GPU_image_sky(GPUMaterial *mat,
                            const float *pixels,
                            float *layer,
                            eGPUSamplerState sampler_state);
+GPUNodeLink *GPU_image_camera(GPUMaterial *mat,
+                              struct Camera *camera,
+                              eGPUSamplerState sampler_state);
 GPUNodeLink *GPU_color_band(GPUMaterial *mat, int size, float *pixels, float *row);
 
 /**
@@ -322,6 +328,7 @@ typedef struct GPUMaterialTexture {
   bool iuser_available;
   struct GPUTexture **colorband;
   struct GPUTexture **sky;
+  struct GPUTexture **camera;
   char sampler_name[32];       /* Name of sampler in GLSL. */
   char tiled_mapping_name[32]; /* Name of tile mapping sampler in GLSL. */
   int users;

source/blender/gpu/intern/gpu_codegen.cc

@@ -400,6 +400,10 @@ void GPUCodegen::generate_resources()
       const char *name = info.name_buffer.append_sampler_name(tex->sampler_name);
       info.sampler(0, ImageType::FLOAT_2D_ARRAY, name, Frequency::BATCH);
     }
+    else if (tex->camera && tex->camera[0]) {
+      const char *name = info.name_buffer.append_sampler_name(tex->sampler_name);
+      info.sampler(slot++, ImageType::FLOAT_2D, name, Frequency::BATCH);
+    }
     else if (tex->tiled_mapping_name[0] != '\0') {
       const char *name = info.name_buffer.append_sampler_name(tex->sampler_name);
       info.sampler(slot++, ImageType::FLOAT_2D_ARRAY, name, Frequency::BATCH);

source/blender/gpu/intern/gpu_node_graph.c

@@ -12,6 +12,7 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "DNA_camera_types.h"
 #include "DNA_node_types.h"
 
 #include "BLI_ghash.h"
@@ -19,6 +20,7 @@
 #include "BLI_string.h"
 #include "BLI_utildefines.h"
 
+#include "GPU_framebuffer.h"
 #include "GPU_texture.h"
 #include "GPU_vertex_format.h"
 
@@ -114,6 +116,7 @@ static void gpu_node_input_link(GPUNode *node, GPUNodeLink *link, const eGPUType
       link->users++;
       break;
     case GPU_NODE_LINK_IMAGE:
+    case GPU_NODE_LINK_IMAGE_CAMERA:
     case GPU_NODE_LINK_IMAGE_TILED:
     case GPU_NODE_LINK_IMAGE_SKY:
     case GPU_NODE_LINK_COLORBAND:
@@ -470,6 +473,7 @@ static GPUMaterialTexture *gpu_node_graph_add_texture(GPUNodeGraph *graph,
                                                       ImageUser *iuser,
                                                       struct GPUTexture **colorband,
                                                       struct GPUTexture **sky,
+                                                      struct GPUTexture **camera,
                                                       GPUNodeLinkType link_type,
                                                       eGPUSamplerState sampler_state)
 {
@@ -478,7 +482,7 @@ static GPUMaterialTexture *gpu_node_graph_add_texture(GPUNodeGraph *graph,
   GPUMaterialTexture *tex = graph->textures.first;
   for (; tex; tex = tex->next) {
     if (tex->ima == ima && tex->colorband == colorband && tex->sky == sky &&
-        tex->sampler_state == sampler_state) {
+        tex->camera == camera && tex->sampler_state == sampler_state) {
       break;
     }
     num_textures++;
@@ -494,6 +498,7 @@ static GPUMaterialTexture *gpu_node_graph_add_texture(GPUNodeGraph *graph,
     }
     tex->colorband = colorband;
     tex->sky = sky;
+    tex->camera = camera;
     tex->sampler_state = sampler_state;
     BLI_snprintf(tex->sampler_name, sizeof(tex->sampler_name), "samp%d", num_textures);
     if (ELEM(link_type, GPU_NODE_LINK_IMAGE_TILED, GPU_NODE_LINK_IMAGE_TILED_MAPPING)) {
@@ -625,7 +630,24 @@ GPUNodeLink *GPU_image(GPUMaterial *mat,
   GPUNodeLink *link = gpu_node_link_create();
   link->link_type = GPU_NODE_LINK_IMAGE;
   link->texture = gpu_node_graph_add_texture(
-      graph, ima, iuser, NULL, NULL, link->link_type, sampler_state);
+      graph, ima, iuser, NULL, NULL, NULL, link->link_type, sampler_state);
+  return link;
+}
+
+GPUNodeLink *GPU_image_camera(GPUMaterial *mat, Camera *camera, eGPUSamplerState sampler_state)
+{
+  GPUNodeGraph *graph = gpu_material_node_graph(mat);
+  GPUNodeLink *link = gpu_node_link_create();
+  link->link_type = GPU_NODE_LINK_IMAGE_CAMERA;
+  link->texture = gpu_node_graph_add_texture(graph,
+                                             NULL,
+                                             NULL,
+                                             NULL,
+                                             NULL,
+                                             &camera->runtime.offscreen_color_texture,
+                                             link->link_type,
+                                             sampler_state);
+  GPU_material_flag_set(mat, GPU_MATFLAG_VIRTUAL_MONITOR);
   return link;
 }
 
@@ -642,7 +664,7 @@ GPUNodeLink *GPU_image_sky(GPUMaterial *mat,
   GPUNodeLink *link = gpu_node_link_create();
   link->link_type = GPU_NODE_LINK_IMAGE_SKY;
   link->texture = gpu_node_graph_add_texture(
-      graph, NULL, NULL, NULL, sky, link->link_type, sampler_state);
+      graph, NULL, NULL, NULL, sky, NULL, link->link_type, sampler_state);
   return link;
 }
 
@@ -655,7 +677,7 @@ GPUNodeLink *GPU_image_tiled(GPUMaterial *mat,
   GPUNodeLink *link = gpu_node_link_create();
   link->link_type = GPU_NODE_LINK_IMAGE_TILED;
   link->texture = gpu_node_graph_add_texture(
-      graph, ima, iuser, NULL, NULL, link->link_type, sampler_state);
+      graph, ima, iuser, NULL, NULL, NULL, link->link_type, sampler_state);
   return link;
 }
 
@@ -665,7 +687,7 @@ GPUNodeLink *GPU_image_tiled_mapping(GPUMaterial *mat, Image *ima, ImageUser *iu
   GPUNodeLink *link = gpu_node_link_create();
   link->link_type = GPU_NODE_LINK_IMAGE_TILED_MAPPING;
   link->texture = gpu_node_graph_add_texture(
-      graph, ima, iuser, NULL, NULL, link->link_type, GPU_SAMPLER_MAX);
+      graph, ima, iuser, NULL, NULL, NULL, link->link_type, GPU_SAMPLER_MAX);
   return link;
 }
 
@@ -678,7 +700,7 @@ GPUNodeLink *GPU_color_band(GPUMaterial *mat, int size, float *pixels, float *ro
   GPUNodeLink *link = gpu_node_link_create();
   link->link_type = GPU_NODE_LINK_COLORBAND;
   link->texture = gpu_node_graph_add_texture(
-      graph, NULL, NULL, colorband, NULL, link->link_type, GPU_SAMPLER_MAX);
+      graph, NULL, NULL, colorband, NULL, NULL, link->link_type, GPU_SAMPLER_MAX);
   return link;
 }
 

source/blender/gpu/intern/gpu_node_graph.h

@@ -50,6 +50,7 @@ typedef enum {
   GPU_NODE_LINK_IMAGE_TILED,
   GPU_NODE_LINK_IMAGE_TILED_MAPPING,
   GPU_NODE_LINK_IMAGE_SKY,
+  GPU_NODE_LINK_IMAGE_CAMERA,
   GPU_NODE_LINK_OUTPUT,
   GPU_NODE_LINK_UNIFORM,
   GPU_NODE_LINK_DIFFERENTIATE_FLOAT_FN,

source/blender/gpu/shaders/material/gpu_shader_material_virtual_camera.glsl

@@ -0,0 +1,11 @@
+void node_virtual_camera_empty(vec3 co, out vec4 color, out float alpha)
+{
+  color = vec4(0.0);
+  alpha = 0.0;
+}
+
+void node_virtual_camera(vec3 co, sampler2D ima, out vec4 color, out float alpha)
+{
+  color = texture(ima, co.xy);
+  alpha = color.a;
+}

source/blender/makesdna/DNA_camera_types.h

@@ -71,6 +71,10 @@ typedef struct Camera_Runtime {
   float drw_depth[2];
   float drw_focusmat[4][4];
   float drw_normalmat[4][4];
+
+  struct GPUOffScreen *virtual_monitor_offscreen;
+  /* Local reference to not owning gpu texture. Used to have a reliable pointer to the texture. */
+  struct GPUTexture *offscreen_color_texture;
 } Camera_Runtime;
 
 typedef struct Camera {

source/blender/makesrna/intern/rna_nodetree.c

@@ -5900,6 +5900,22 @@ static void def_sh_tex_coord(StructRNA *srna)
   RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_update");
 }
 
+static void def_sh_virtual_monitor(StructRNA *srna)
+{
+  PropertyRNA *prop;
+
+  prop = RNA_def_property(srna, "camera", PROP_POINTER, PROP_NONE);
+  RNA_def_property_flag(prop, PROP_EDITABLE);
+  RNA_def_property_override_flag(prop, PROPOVERRIDE_OVERRIDABLE_LIBRARY);
+  RNA_def_property_pointer_sdna(prop, NULL, "id");
+  RNA_def_property_pointer_funcs(prop, NULL, NULL, NULL, "rna_Camera_object_poll");
+  RNA_def_property_struct_type(prop, "Object");
+  RNA_def_property_ui_text(prop, "Camera", "");
+  RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_update");
+  /* TODO: add poll function show all cameras in active scene and view layer, excluding scene
+   * camera. */
+}
+
 static void def_sh_vect_transform(StructRNA *srna)
 {
   static const EnumPropertyItem prop_vect_type_items[] = {

source/blender/nodes/NOD_shader.h

@@ -129,6 +129,8 @@ void register_node_type_sh_bump(void);
 void register_node_type_sh_tex_ies(void);
 void register_node_type_sh_tex_white_noise(void);
 
+void register_node_type_sh_virtual_camera(void);
+
 void register_node_type_sh_custom_group(bNodeType *ntype);
 
 struct bNodeTreeExec *ntreeShaderBeginExecTree(struct bNodeTree *ntree);

source/blender/nodes/NOD_static_types.h

@@ -123,6 +123,7 @@ DefNode(ShaderNode,     SH_NODE_CURVE_FLOAT,        def_float_curve,        "CUR
 DefNode(ShaderNode,     SH_NODE_COMBINE_COLOR,      def_sh_combsep_color,   "COMBINE_COLOR",      CombineColor,     "Combine Color",     "Create a color from individual components using multiple models")
 DefNode(ShaderNode,     SH_NODE_SEPARATE_COLOR,     def_sh_combsep_color,   "SEPARATE_COLOR",     SeparateColor,    "Separate Color",    "Split a color into its individual components using multiple models")
 DefNode(ShaderNode,     SH_NODE_MIX,                def_sh_mix,             "MIX",                Mix,              "Mix",               "Mix values by a factor")
+DefNode(ShaderNode,     SH_NODE_VIRTUAL_MONITOR,    def_sh_virtual_monitor, "VIRTUAL_MONITOR",    VirtualMonitor,   "Virtual Monitor",   "Use the feed from a virtual camera (has to be in the same scene and view layer)")
 
 DefNode(CompositorNode, CMP_NODE_VIEWER,         def_cmp_viewer,         "VIEWER",         Viewer,           "Viewer",            ""              )
 DefNode(CompositorNode, CMP_NODE_RGB,            0,                      "RGB",            RGB,              "RGB",               ""              )

source/blender/nodes/shader/CMakeLists.txt

@@ -113,6 +113,7 @@ set(SRC
   nodes/node_shader_vector_rotate.cc
   nodes/node_shader_vector_transform.cc
   nodes/node_shader_vertex_color.cc
+  nodes/node_shader_virtual_monitor.cc
   nodes/node_shader_volume_absorption.cc
   nodes/node_shader_volume_info.cc
   nodes/node_shader_volume_principled.cc

source/blender/nodes/shader/nodes/node_shader_virtual_monitor.cc

@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright 2005 Blender Foundation. All rights reserved. */
+
+#include "node_shader_util.hh"
+
+#include "DNA_camera_types.h"
+
+#include "DEG_depsgraph_query.h"
+
+namespace blender::nodes::node_shader_virtual_monitor_cc {
+
+static void sh_node_virtual_monitor_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Vector>(N_("Vector")).implicit_field(implicit_field_inputs::position);
+  b.add_output<decl::Color>(N_("Color")).no_muted_links();
+  b.add_output<decl::Float>(N_("Alpha")).no_muted_links();
+}
+
+static int node_shader_gpu_virtual_monitor(GPUMaterial *mat,
+                                           bNode *node,
+                                           bNodeExecData * /*execdata*/,
+                                           GPUNodeStack *in,
+                                           GPUNodeStack *out)
+{
+  Object *object = (Object *)node->id;
+  if (object == nullptr || object->type != OB_CAMERA) {
+    return GPU_stack_link(mat, node, "node_virtual_camera_empty", in, out);
+  }
+
+  Object *orig_object = DEG_get_original_object(object);
+
+  Camera *cam = static_cast<Camera *>(orig_object->data);
+  node_shader_gpu_default_tex_coord(mat, node, &in[0].link);
+
+  return GPU_stack_link(
+      mat, node, "node_virtual_camera", in, out, GPU_image_camera(mat, cam, GPU_SAMPLER_DEFAULT));
+}
+
+}  // namespace blender::nodes::node_shader_virtual_monitor_cc
+
+void register_node_type_sh_virtual_camera()
+{
+  namespace file_ns = blender::nodes::node_shader_virtual_monitor_cc;
+
+  static bNodeType ntype;
+
+  sh_node_type_base(&ntype, SH_NODE_VIRTUAL_MONITOR, "Virtual Monitor", NODE_CLASS_INPUT);
+  ntype.declare = file_ns::sh_node_virtual_monitor_declare;
+  ntype.gpu_fn = file_ns::node_shader_gpu_virtual_monitor;
+
+  nodeRegisterType(&ntype);
+}

source/blender/python/gpu/gpu_py_offscreen.c

@@ -398,6 +398,7 @@ static PyObject *pygpu_offscreen_draw_view3d(BPyGPUOffScreen *self, PyObject *ar
                            "",
                            do_color_management,
                            true,
+                           false,
                            self->ofs,
                            self->viewport);