Curves edit mode: show dots for points

This adds support to show dots for the curves points when in edit mode,
using a specific overlay.

This also adds `DRW_curves_batch_cache_create_requested` which for now
only creates the point buffer for the newly added `edit_points` batch.
In the future, this will also handle other edit mode overlays, and
probably also replace the current curves batch cache creation.

Maniphest Tasks: T95770

Differential Revision: https://developer.blender.org/D14262

1 files changed, 92 insertions, 0 deletions

diff --git a/source/blender/draw/engines/overlay/overlay_edit_curves.cc b/source/blender/draw/engines/overlay/overlay_edit_curves.cc
new file mode 100644
index 00000000000..02e40ea0304
--- /dev/null
+++ b/source/blender/draw/engines/overlay/overlay_edit_curves.cc
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright 2022 Blender Foundation. */
+
+/** \file
+ * \ingroup draw_engine
+ */
+
+#include "DRW_render.h"
+
+#include "ED_view3d.h"
+
+#include "draw_cache_impl.h"
+
+#include "overlay_private.h"
+
+void OVERLAY_edit_curves_init(OVERLAY_Data *vedata)
+{
+  OVERLAY_PrivateData *pd = vedata->stl->pd;
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+
+  pd->edit_curves.do_zbufclip = XRAY_FLAG_ENABLED(draw_ctx->v3d);
+
+  /* Create view with depth offset. */
+  DRWView *default_view = (DRWView *)DRW_view_default_get();
+  pd->view_edit_curves_points = default_view;
+}
+
+void OVERLAY_edit_curves_cache_init(OVERLAY_Data *vedata)
+{
+  OVERLAY_TextureList *txl = vedata->txl;
+  OVERLAY_PassList *psl = vedata->psl;
+  OVERLAY_PrivateData *pd = vedata->stl->pd;
+
+  /* Desired masks (write to color and depth) and blend mode for rendering. */
+  DRWState state = (DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_LESS_EQUAL | DRW_STATE_BLEND_ALPHA |
+                    DRW_STATE_WRITE_DEPTH);
+
+  /* Common boilerplate for shading groups. */
+  DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+  const View3D *v3d = draw_ctx->v3d;
+  GPUTexture **depth_tex = (pd->edit_curves.do_zbufclip) ? &dtxl->depth : &txl->dummy_depth_tx;
+  const float backwire_opacity = (pd->edit_curves.do_zbufclip) ? v3d->overlay.backwire_opacity :
+                                                                 1.0f;
+
+  /* Run Twice for in-front passes. */
+  for (int i = 0; i < 2; i++) {
+    DRW_PASS_CREATE(psl->edit_curves_points_ps[i], (state | pd->clipping_state));
+
+    GPUShader *sh = OVERLAY_shader_edit_curve_point();
+    DRWShadingGroup *grp = pd->edit_curves_points_grp[i] = DRW_shgroup_create(
+        sh, psl->edit_curves_points_ps[i]);
+    DRW_shgroup_uniform_block(grp, "globalsBlock", G_draw.block_ubo);
+    DRW_shgroup_uniform_float_copy(grp, "alpha", backwire_opacity);
+    DRW_shgroup_uniform_texture_ref(grp, "depthTex", depth_tex);
+  }
+}
+
+static void overlay_edit_curves_add_ob_to_pass(OVERLAY_PrivateData *pd, Object *ob, bool in_front)
+{
+  Curves *curves = static_cast<Curves *>(ob->data);
+  DRWShadingGroup *point_shgrp = pd->edit_curves_points_grp[in_front];
+  struct GPUBatch *geom_points = DRW_curves_batch_cache_get_edit_points(curves);
+  DRW_shgroup_call_no_cull(point_shgrp, geom_points, ob);
+}
+
+void OVERLAY_edit_curves_cache_populate(OVERLAY_Data *vedata, Object *ob)
+{
+  OVERLAY_PrivateData *pd = vedata->stl->pd;
+
+  if (pd->edit_curves.do_zbufclip) {
+    overlay_edit_curves_add_ob_to_pass(pd, ob, false);
+  }
+  else {
+    overlay_edit_curves_add_ob_to_pass(pd, ob, true);
+  }
+}
+
+void OVERLAY_edit_curves_draw(OVERLAY_Data *vedata)
+{
+  OVERLAY_PassList *psl = vedata->psl;
+  OVERLAY_PrivateData *pd = vedata->stl->pd;
+
+  if (pd->edit_curves.do_zbufclip) {
+    DRW_view_set_active(pd->view_edit_curves_points);
+    DRW_draw_pass(psl->edit_curves_points_ps[NOT_IN_FRONT]);
+  }
+  else {
+    DRW_view_set_active(pd->view_edit_curves_points);
+    DRW_draw_pass(psl->edit_curves_points_ps[IN_FRONT]);
+  }
+}