text: /*
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version 2
   * of the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
   *
   * Copyright 2016, Blender Foundation.
   */
  
  /** \file
   * \ingroup draw
   */
  #include "BKE_modifier.h"
  
  #include "DNA_modifier_types.h"
  #include "DNA_view3d_types.h"
  
  #include "DRW_engine.h"
  #include "DRW_render.h"
  
  #include "ED_view3d.h"
  
  /* If builtin shaders are needed */
  #include "GPU_shader.h"
  
  #include "draw_common.h"
  #include "draw_mode_engines.h"
  
  /* *********** LISTS *********** */
  /**
   * All lists are per viewport specific datas.
   * They are all free when viewport changes engines
   * or is free itself. Use #POSE_engine_init() to
   * initialize most of them and #POSE_cache_init()
   * for #POSE_PassList
   */
  
  typedef struct POSE_PassList {
    struct DRWPass *bone_solid[2];
    struct DRWPass *bone_transp[2];
    struct DRWPass *bone_outline[2];
    struct DRWPass *bone_wire[2];
    struct DRWPass *bone_envelope[2];
    struct DRWPass *bone_axes;
    struct DRWPass *relationship[2];
    struct DRWPass *bone_selection;
  } POSE_PassList;
  
  typedef struct POSE_StorageList {
    struct POSE_PrivateData *g_data;
  } POSE_StorageList;
  
  typedef struct POSE_Data {
    void *engine_type;
    DRWViewportEmptyList *fbl;
    DRWViewportEmptyList *txl;
    POSE_PassList *psl;
    POSE_StorageList *stl;
  } POSE_Data;
  
  /* *********** STATIC *********** */
  
  typedef struct POSE_PrivateData {
    DRWShadingGroup *bone_selection_shgrp;
    DRWShadingGroup *bone_selection_invert_shgrp;
    GHash *custom_shapes[2];
    float blend_color[4];
    float blend_color_invert[4];
    bool transparent_bones;
  } POSE_PrivateData; /* Transient data */
  
  static struct {
    struct GPUShader *bone_selection_sh;
  } e_data = {NULL};
  
  /* *********** FUNCTIONS *********** */
  static bool POSE_is_bone_selection_overlay_active(void)
  {
    const DRWContextState *draw_ctx = DRW_context_state_get();
    const View3D *v3d = draw_ctx->v3d;
    return v3d && (v3d->overlay.flag & V3D_OVERLAY_BONE_SELECT) && draw_ctx->object_pose;
  }
  
  static void POSE_engine_init(void *UNUSED(vedata))
  {
    if (!e_data.bone_selection_sh) {
      e_data.bone_selection_sh = GPU_shader_get_builtin_shader(GPU_SHADER_3D_UNIFORM_COLOR);
    }
  }
  
  static void POSE_engine_free(void)
  {
  }
  
  /* Here init all passes and shading groups
   * Assume that all Passes are NULL */
  static void POSE_cache_init(void *vedata)
  {
    POSE_PassList *psl = ((POSE_Data *)vedata)->psl;
    POSE_StorageList *stl = ((POSE_Data *)vedata)->stl;
    const DRWContextState *draw_ctx = DRW_context_state_get();
    View3D *v3d = draw_ctx->v3d;
  
    if (!stl->g_data) {
      /* Alloc transient pointers */
      stl->g_data = MEM_callocN(sizeof(*stl->g_data), __func__);
    }
    POSE_PrivateData *ppd = stl->g_data;
    ppd->transparent_bones = (draw_ctx->v3d->shading.type == OB_WIRE);
  
    for (int i = 0; i < 2; ++i) {
      /* Solid bones */
      DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_LESS_EQUAL | DRW_STATE_CULL_BACK;
      psl->bone_solid[i] = DRW_pass_create("Bone Solid Pass", state | DRW_STATE_WRITE_DEPTH);
      psl->bone_transp[i] = DRW_pass_create("Bone Transp Pass", state | DRW_STATE_BLEND);
  
      /* Bones Outline */
      state = DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS_EQUAL;
      psl->bone_outline[i] = DRW_pass_create("Bone Outline Pass", state);
  
      /* Wire bones */
      state = DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS_EQUAL |
              DRW_STATE_BLEND;
      psl->bone_wire[i] = DRW_pass_create("Bone Wire Pass", state);
  
      /* distance outline around envelope bones */
      state = DRW_STATE_ADDITIVE | DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_LESS_EQUAL |
              DRW_STATE_CULL_FRONT;
      psl->bone_envelope[i] = DRW_pass_create("Bone Envelope Outline Pass", state);
  
      state = DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS_EQUAL |
              DRW_STATE_BLEND | DRW_STATE_WIRE;
      psl->relationship[i] = DRW_pass_create("Bone Relationship Pass", state);
  
      ppd->custom_shapes[i] = BLI_ghash_ptr_new(__func__);
    }
  
    {
      DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_WIRE_SMOOTH | DRW_STATE_BLEND;
      psl->bone_axes = DRW_pass_create("Bone Axes Pass", state);
    }
  
    {
      if (POSE_is_bone_selection_overlay_active()) {
        const float alpha = (draw_ctx->object_mode & OB_MODE_WEIGHT_PAINT) ?
                                0.0f :
                                v3d->overlay.xray_alpha_bone;
        copy_v4_fl4(ppd->blend_color, 0.0f, 0.0f, 0.0f, alpha);
        copy_v4_fl4(ppd->blend_color_invert, 0.0f, 0.0f, 0.0f, pow(alpha, 4));
        DRWShadingGroup *grp;
        psl->bone_selection = DRW_pass_create(
            "Bone Selection", DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL | DRW_STATE_BLEND);
        grp = DRW_shgroup_create(e_data.bone_selection_sh, psl->bone_selection);
        DRW_shgroup_uniform_vec4(grp, "color", ppd->blend_color, 1);
        stl->g_data->bone_selection_shgrp = grp;
        grp = DRW_shgroup_create(e_data.bone_selection_sh, psl->bone_selection);
        DRW_shgroup_uniform_vec4(grp, "color", ppd->blend_color_invert, 1);
        stl->g_data->bone_selection_invert_shgrp = grp;
      }
    }
  }
  
  static bool POSE_is_driven_by_active_armature(Object *ob)
  {
    Object *ob_arm = modifiers_isDeformedByArmature(ob);
    if (ob_arm) {
      const DRWContextState *draw_ctx = DRW_context_state_get();
      bool is_active = DRW_pose_mode_armature(ob_arm, draw_ctx->obact);
      if (!is_active && ob_arm->proxy_from) {
        is_active = DRW_pose_mode_armature(ob_arm->proxy_from, draw_ctx->obact);
      }
      return is_active;
    }
    else {
      Object *ob_mesh_deform = modifiers_isDeformedByMeshDeform(ob);
      if (ob_mesh_deform) {
        return POSE_is_driven_by_active_armature(ob_mesh_deform);
      }
    }
    return false;
  }
  
  /* Add geometry to shading groups. Execute for each objects */
  static void POSE_cache_populate(void *vedata, Object *ob)
  {
    POSE_PassList *psl = ((POSE_Data *)vedata)->psl;
    POSE_PrivateData *ppd = ((POSE_Data *)vedata)->stl->g_data;
    const DRWContextState *draw_ctx = DRW_context_state_get();
  
    /* In the future this will allow us to implement face gizmos,
     * and similar functionalities. For now we handle only pose bones. */
  
    if (ob->type == OB_ARMATURE) {
      if ((draw_ctx->v3d->flag2 & V3D_HIDE_OVERLAYS) ||
          (draw_ctx->v3d->overlay.flag & V3D_OVERLAY_HIDE_BONES)) {
        return;
      }
      if (DRW_pose_mode_armature(ob, draw_ctx->obact)) {
        int ghost = (ob->dtx & OB_DRAWXRAY) ? 1 : 0;
        bool transp = (ppd->transparent_bones || (ob->dt <= OB_WIRE)) ||
                      XRAY_FLAG_ENABLED(draw_ctx->v3d);
  
        DRWArmaturePasses passes = {
            .bone_solid = (transp) ? psl->bone_transp[ghost] : psl->bone_solid[ghost],
            .bone_outline = psl->bone_outline[ghost],
            .bone_wire = psl->bone_wire[ghost],
            .bone_envelope = psl->bone_envelope[ghost],
            .bone_axes = psl->bone_axes,
            .relationship_lines = psl->relationship[ghost],
            .custom_shapes = ppd->custom_shapes[transp],
        };
        DRW_shgroup_armature_pose(ob, passes, transp);
      }
    }
    else if (ob->type == OB_MESH && !DRW_state_is_select() &&
             POSE_is_bone_selection_overlay_active()) {
      struct GPUBatch *geom = DRW_cache_object_surface_get(ob);
      if (geom) {
        if (POSE_is_driven_by_active_armature(ob)) {
          DRW_shgroup_call_object(ppd->bone_selection_shgrp, geom, ob);
        }
        else {
          DRW_shgroup_call_object(ppd->bone_selection_invert_shgrp, geom, ob);
        }
      }
    }
  }
  
  static void POSE_cache_finish(void *vedata)
  {
    POSE_PrivateData *ppd = ((POSE_Data *)vedata)->stl->g_data;
  
    /* TODO(fclem): Do not free it for each frame but reuse it. Avoiding alloc cost. */
    for (int i = 0; i < 2; i++) {
      BLI_ghash_free(ppd->custom_shapes[i], NULL, NULL);
    }
  }
  
  /**
   * Return true if armature should be handled by the pose mode engine.
   */
  bool DRW_pose_mode_armature(Object *ob, Object *active_ob)
  {
    const DRWContextState *draw_ctx = DRW_context_state_get();
  
    /* Pose armature is handled by pose mode engine. */
    if (((ob == active_ob) || (ob->mode & OB_MODE_POSE)) &&
        ((draw_ctx->object_mode & OB_MODE_POSE) != 0)) {
      return true;
    }
  
    /* Armature parent is also handled by pose mode engine. */
    if ((active_ob != NULL) && ((draw_ctx->object_mode & OB_MODE_WEIGHT_PAINT) != 0)) {
      if (ob == draw_ctx->object_pose) {
        return true;
      }
    }
  
    return false;
  }
  
  /* Draw time ! Control rendering pipeline from here */
  static void POSE_draw_scene(void *vedata)
  {
    POSE_PassList *psl = ((POSE_Data *)vedata)->psl;
    DefaultFramebufferList *dfbl = DRW_viewport_framebuffer_list_get();
    DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
    const bool bone_selection_overlay = POSE_is_bone_selection_overlay_active();
  
    if (DRW_state_is_select()) {
      DRW_draw_pass(psl->bone_outline[0]);
      DRW_draw_pass(psl->bone_solid[0]);
      DRW_draw_pass(psl->bone_wire[0]);
      DRW_draw_pass(psl->bone_outline[1]);
      DRW_draw_pass(psl->bone_solid[1]);
      DRW_draw_pass(psl->bone_wire[1]);
      return;
    }
  
    if (bone_selection_overlay) {
      GPU_framebuffer_bind(dfbl->default_fb);
      DRW_draw_pass(psl->bone_selection);
      GPU_framebuffer_bind(dfbl->depth_only_fb);
      GPU_framebuffer_clear_depth(dfbl->depth_only_fb, 1.0);
      GPU_framebuffer_bind(dfbl->default_fb);
    }
  
    DRW_draw_pass(psl->bone_envelope[0]);
    DRW_draw_pass(psl->bone_transp[0]);
  
    MULTISAMPLE_SYNC_ENABLE(dfbl, dtxl);
  
    DRW_draw_pass(psl->bone_solid[0]);
    DRW_draw_pass(psl->bone_outline[0]);
    DRW_draw_pass(psl->bone_wire[0]);
    DRW_draw_pass(psl->relationship[0]);
  
    MULTISAMPLE_SYNC_DISABLE(dfbl, dtxl);
  
    if (!DRW_pass_is_empty(psl->bone_envelope[1]) || !DRW_pass_is_empty(psl->bone_transp[1]) ||
        !DRW_pass_is_empty(psl->bone_solid[1]) || !DRW_pass_is_empty(psl->bone_outline[1]) ||
        !DRW_pass_is_empty(psl->bone_wire[1]) || !DRW_pass_is_empty(psl->relationship[1])) {
      if (DRW_state_is_fbo()) {
        GPU_framebuffer_bind(dfbl->default_fb);
        GPU_framebuffer_clear_depth(dfbl->default_fb, 1.0f);
      }
  
      DRW_draw_pass(psl->bone_envelope[1]);
      DRW_draw_pass(psl->bone_solid[1]);
      DRW_draw_pass(psl->bone_transp[1]);
      DRW_draw_pass(psl->bone_outline[1]);
      DRW_draw_pass(psl->bone_wire[1]);
      DRW_draw_pass(psl->relationship[1]);
    }
  
    /* Draw axes with linesmooth and outside of multisample buffer. */
    DRW_draw_pass(psl->bone_axes);
  }
  
  static const DrawEngineDataSize POSE_data_size = DRW_VIEWPORT_DATA_SIZE(POSE_Data);
  
  DrawEngineType draw_engine_pose_type = {
      NULL,
      NULL,
      N_("PoseMode"),
      &POSE_data_size,
      &POSE_engine_init,
      &POSE_engine_free,
      &POSE_cache_init,
      &POSE_cache_populate,
      &POSE_cache_finish,
      NULL,
      &POSE_draw_scene,
      NULL,
      NULL,
  };
  