EEVEE-Next: Add Film and RenderBuffers module

This modules handles renderpasses allocation and filling. Also handles
blitting to viewport framebuffer and render result reading.

Changes against the old implementation:
- the filling of the renderpasses happens all at once requiring
  only 1 geometry pass.
- The filtering is optimized with weights precomputed on CPU and
  reuse of neighboor pixels.
- Only one accumulation buffer for renderpasses (no ping-pong).
- Accumulation happens in one pass for every passes using a single
  dispatch or fullscreen triangle pass.

TAA and history reprojection is not yet implemented.
AOVs support is present but with a 16 AOV limit for now.
Cryptomatte is not yet implemented.

source/blender/draw/engines/eevee_next/eevee_renderbuffers.cc

@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright 2021 Blender Foundation.
+ */
+
+/** \file
+ * \ingroup eevee
+ *
+ * A film is a fullscreen buffer (usually at output extent)
+ * that will be able to accumulate sample in any distorted camera_type
+ * using a pixel filter.
+ *
+ * Input needs to be jittered so that the filter converges to the right result.
+ */
+
+#include "BLI_rect.h"
+
+#include "GPU_framebuffer.h"
+#include "GPU_texture.h"
+
+#include "DRW_render.h"
+
+#include "eevee_film.hh"
+#include "eevee_instance.hh"
+
+namespace blender::eevee {
+
+void RenderBuffers::sync()
+{
+  depth_tx.sync();
+  combined_tx.sync();
+
+  normal_tx.sync();
+  vector_tx.sync();
+  diffuse_light_tx.sync();
+  diffuse_color_tx.sync();
+  specular_light_tx.sync();
+  specular_color_tx.sync();
+  volume_light_tx.sync();
+  emission_tx.sync();
+  environment_tx.sync();
+  shadow_tx.sync();
+  ambient_occlusion_tx.sync();
+}
+
+void RenderBuffers::acquire(int2 extent, void *owner)
+{
+  auto pass_extent = [&](eViewLayerEEVEEPassType pass_bit) -> int2 {
+    /* Use dummy texture for disabled passes. Allows correct bindings. */
+    return (inst_.film.enabled_passes_get() & pass_bit) ? extent : int2(1);
+  };
+
+  eGPUTextureFormat color_format = GPU_RGBA16F;
+  eGPUTextureFormat float_format = GPU_R16F;
+
+  /* Depth and combined are always needed. */
+  depth_tx.acquire(extent, GPU_DEPTH24_STENCIL8, owner);
+  combined_tx.acquire(extent, color_format, owner);
+
+  normal_tx.acquire(pass_extent(EEVEE_RENDER_PASS_NORMAL), color_format, owner);
+  vector_tx.acquire(pass_extent(EEVEE_RENDER_PASS_VECTOR), color_format, owner);
+  diffuse_light_tx.acquire(pass_extent(EEVEE_RENDER_PASS_DIFFUSE_LIGHT), color_format, owner);
+  diffuse_color_tx.acquire(pass_extent(EEVEE_RENDER_PASS_DIFFUSE_COLOR), color_format, owner);
+  specular_light_tx.acquire(pass_extent(EEVEE_RENDER_PASS_SPECULAR_LIGHT), color_format, owner);
+  specular_color_tx.acquire(pass_extent(EEVEE_RENDER_PASS_SPECULAR_COLOR), color_format, owner);
+  volume_light_tx.acquire(pass_extent(EEVEE_RENDER_PASS_VOLUME_LIGHT), color_format, owner);
+  emission_tx.acquire(pass_extent(EEVEE_RENDER_PASS_EMIT), color_format, owner);
+  environment_tx.acquire(pass_extent(EEVEE_RENDER_PASS_ENVIRONMENT), color_format, owner);
+  shadow_tx.acquire(pass_extent(EEVEE_RENDER_PASS_SHADOW), float_format, owner);
+  ambient_occlusion_tx.acquire(pass_extent(EEVEE_RENDER_PASS_AO), float_format, owner);
+
+  const AOVsInfoData &aovs = inst_.film.aovs_info;
+  aov_color_tx.ensure_2d_array(
+      color_format, (aovs.color_len > 0) ? extent : int2(1), max_ii(1, aovs.color_len));
+  aov_value_tx.ensure_2d_array(
+      float_format, (aovs.value_len > 0) ? extent : int2(1), max_ii(1, aovs.value_len));
+}
+
+void RenderBuffers::release()
+{
+  depth_tx.release();
+  combined_tx.release();
+
+  normal_tx.release();
+  vector_tx.release();
+  diffuse_light_tx.release();
+  diffuse_color_tx.release();
+  specular_light_tx.release();
+  specular_color_tx.release();
+  volume_light_tx.release();
+  emission_tx.release();
+  environment_tx.release();
+  shadow_tx.release();
+  ambient_occlusion_tx.release();
+}
+
+}  // namespace blender::eevee