GPU: Framebuffer: Add multi viewport support

This add the possibility to define different
viewports inside a single framebuffer and
let the vertex shader decide which viewport
to render to.

This only contain the GL and VK implementation.
The Vulkan implementation works but still
has a validation error related to shader features
and extension. The test passes nonetheless.

Pull Request: https://projects.blender.org/blender/blender/pulls/110923

intern/ghost/intern/GHOST_ContextVK.cc

@@ -219,6 +219,7 @@ class GHOST_DeviceVK {
     device_features.dualSrcBlend = VK_TRUE;
     device_features.logicOp = VK_TRUE;
     device_features.imageCubeArray = VK_TRUE;
+    device_features.multiViewport = VK_TRUE;
 #endif
 
     VkDeviceCreateInfo device_create_info = {};

source/blender/gpu/CMakeLists.txt

@@ -571,6 +571,7 @@ set(GLSL_SRC_TEST
   tests/shaders/gpu_compute_ssbo_test.glsl
   tests/shaders/gpu_compute_vbo_test.glsl
   tests/shaders/gpu_compute_dummy_test.glsl
+  tests/shaders/gpu_framebuffer_layer_viewport_test.glsl
   tests/shaders/gpu_push_constants_test.glsl
 )
 

source/blender/gpu/GPU_framebuffer.h

@@ -35,6 +35,9 @@ typedef enum eGPUFrameBufferBits {
 
 ENUM_OPERATORS(eGPUFrameBufferBits, GPU_STENCIL_BIT)
 
+/* Guaranteed by the spec and is never greater than 16 on any hardware or implementation. */
+#define GPU_MAX_VIEWPORTS 16
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -340,10 +343,23 @@ void GPU_framebuffer_default_size(GPUFrameBuffer *framebuffer, int width, int he
  * or when binding the frame-buffer after modifying its attachments.
  *
  * \note Viewport and scissor size is stored per frame-buffer.
+ * \note Setting a singular viewport will only change the state of the first viewport.
+ * \note Must be called after first bind.
  */
 void GPU_framebuffer_viewport_set(
     GPUFrameBuffer *framebuffer, int x, int y, int width, int height);
 
+/**
+ * Similar to `GPU_framebuffer_viewport_set()` but specify the bounds of all 16 viewports.
+ * By default geometry renders only to the first viewport. That can be changed by setting
+ * `gpu_ViewportIndex` in the vertex.
+ *
+ * \note Viewport and scissor size is stored per frame-buffer.
+ * \note Must be called after first bind.
+ */
+void GPU_framebuffer_multi_viewports_set(GPUFrameBuffer *gpu_fb,
+                                         const int viewport_rects[GPU_MAX_VIEWPORTS][4]);
+
 /**
  * Return the viewport offset and size in a int quadruple: (x, y, width, height).
  * \note Viewport and scissor size is stored per frame-buffer.

source/blender/gpu/intern/gpu_framebuffer.cc

@@ -391,6 +391,12 @@ void GPU_framebuffer_viewport_set(GPUFrameBuffer *gpu_fb, int x, int y, int widt
   unwrap(gpu_fb)->viewport_set(viewport_rect);
 }
 
+void GPU_framebuffer_multi_viewports_set(GPUFrameBuffer *gpu_fb,
+                                         const int viewport_rects[GPU_MAX_VIEWPORTS][4])
+{
+  unwrap(gpu_fb)->viewport_multi_set(viewport_rects);
+}
+
 void GPU_framebuffer_viewport_get(GPUFrameBuffer *gpu_fb, int r_viewport[4])
 {
   unwrap(gpu_fb)->viewport_get(r_viewport);

source/blender/gpu/intern/gpu_framebuffer_private.hh

@@ -81,8 +81,9 @@ class FrameBuffer {
   /** Debug name. */
   char name_[DEBUG_NAME_LEN];
   /** Frame-buffer state. */
-  int viewport_[4] = {0};
+  int viewport_[GPU_MAX_VIEWPORTS][4] = {{0}};
   int scissor_[4] = {0};
+  bool multi_viewport_ = false;
   bool scissor_test_ = false;
   bool dirty_state_ = true;
 
@@ -157,10 +158,22 @@ class FrameBuffer {
 
   inline void viewport_set(const int viewport[4])
   {
-    if (!equals_v4v4_int(viewport_, viewport)) {
-      copy_v4_v4_int(viewport_, viewport);
+    if (!equals_v4v4_int(viewport_[0], viewport)) {
+      copy_v4_v4_int(viewport_[0], viewport);
       dirty_state_ = true;
     }
+    multi_viewport_ = false;
+  }
+
+  inline void viewport_multi_set(const int viewports[GPU_MAX_VIEWPORTS][4])
+  {
+    for (size_t i = 0; i < GPU_MAX_VIEWPORTS; i++) {
+      if (!equals_v4v4_int(viewport_[i], viewports[i])) {
+        copy_v4_v4_int(viewport_[i], viewports[i]);
+        dirty_state_ = true;
+      }
+    }
+    multi_viewport_ = true;
   }
 
   inline void scissor_set(const int scissor[4])
@@ -178,7 +191,7 @@ class FrameBuffer {
 
   inline void viewport_get(int r_viewport[4]) const
   {
-    copy_v4_v4_int(r_viewport, viewport_);
+    copy_v4_v4_int(r_viewport, viewport_[0]);
   }
 
   inline void scissor_get(int r_scissor[4]) const

source/blender/gpu/intern/gpu_shader_create_info.hh

@@ -178,6 +178,11 @@ enum class BuiltinBits {
   VERTEX_ID = (1 << 14),
   WORK_GROUP_ID = (1 << 15),
   WORK_GROUP_SIZE = (1 << 16),
+  /**
+   * Allow setting the target viewport when using multi viewport feature.
+   * \note Emulated through geometry shader on older hardware.
+   */
+  VIEWPORT_INDEX = (1 << 17),
 
   /* Not a builtin but a flag we use to tag shaders that use the debug features. */
   USE_DEBUG_DRAW = (1 << 29),

source/blender/gpu/metal/mtl_framebuffer.mm

@@ -780,8 +780,8 @@ void MTLFrameBuffer::apply_state()
 
     /* Ensure viewport has been set. NOTE: This should no longer happen, but kept for safety to
      * track bugs. If viewport size is zero, use framebuffer size. */
-    int viewport_w = viewport_[2];
-    int viewport_h = viewport_[3];
+    int viewport_w = viewport_[0][2];
+    int viewport_h = viewport_[0][3];
     if (viewport_w == 0 || viewport_h == 0) {
       MTL_LOG_WARNING("Viewport had width and height of (0,0) -- Updating -- DEBUG Safety check");
       viewport_w = default_width_;
@@ -789,7 +789,7 @@ void MTLFrameBuffer::apply_state()
     }
 
     /* Update Context State. */
-    mtl_ctx->set_viewport(viewport_[0], viewport_[1], viewport_w, viewport_h);
+    mtl_ctx->set_viewport(viewport_[0][0], viewport_[0][1], viewport_w, viewport_h);
     mtl_ctx->set_scissor(scissor_[0], scissor_[1], scissor_[2], scissor_[3]);
     mtl_ctx->set_scissor_enabled(scissor_test_);
 

source/blender/gpu/opengl/gl_backend.cc

@@ -592,7 +592,8 @@ void GLBackend::capabilities_init()
   GLContext::explicit_location_support = epoxy_gl_version() >= 43;
   GLContext::geometry_shader_invocations = epoxy_has_gl_extension("GL_ARB_gpu_shader5");
   GLContext::fixed_restart_index_support = epoxy_has_gl_extension("GL_ARB_ES3_compatibility");
-  GLContext::layered_rendering_support = epoxy_has_gl_extension("GL_AMD_vertex_shader_layer");
+  GLContext::layered_rendering_support = epoxy_has_gl_extension(
+      "GL_ARB_shader_viewport_layer_array");
   GLContext::native_barycentric_support = epoxy_has_gl_extension(
       "GL_AMD_shader_explicit_vertex_parameter");
   GLContext::multi_bind_support = GLContext::multi_bind_image_support = epoxy_has_gl_extension(

source/blender/gpu/opengl/gl_framebuffer.cc

@@ -43,10 +43,10 @@ GLFrameBuffer::GLFrameBuffer(
   height_ = h;
   srgb_ = false;
 
-  viewport_[0] = scissor_[0] = 0;
-  viewport_[1] = scissor_[1] = 0;
-  viewport_[2] = scissor_[2] = w;
-  viewport_[3] = scissor_[3] = h;
+  viewport_[0][0] = scissor_[0] = 0;
+  viewport_[0][1] = scissor_[1] = 0;
+  viewport_[0][2] = scissor_[2] = w;
+  viewport_[0][3] = scissor_[3] = h;
 
   if (fbo_id_) {
     debug::object_label(GL_FRAMEBUFFER, fbo_id_, name_);
@@ -230,7 +230,20 @@ void GLFrameBuffer::apply_state()
     return;
   }
 
-  glViewport(UNPACK4(viewport_));
+  if (multi_viewport_ == false) {
+    glViewport(UNPACK4(viewport_[0]));
+  }
+  else {
+    /* Great API you have there! You have to convert to float values for setting int viewport
+     * values. **Audible Facepalm** */
+    float viewports_f[GPU_MAX_VIEWPORTS][4];
+    for (int i = 0; i < GPU_MAX_VIEWPORTS; i++) {
+      for (int j = 0; j < 4; j++) {
+        viewports_f[i][j] = viewport_[i][j];
+      }
+    }
+    glViewportArrayv(0, GPU_MAX_VIEWPORTS, viewports_f[0]);
+  }
   glScissor(UNPACK4(scissor_));
 
   if (scissor_test_) {

source/blender/gpu/opengl/gl_shader.cc

@@ -551,6 +551,10 @@ std::string GLShader::vertex_interface_declare(const ShaderCreateInfo &info) con
   if (!GLContext::layered_rendering_support && bool(info.builtins_ & BuiltinBits::LAYER)) {
     ss << "out int gpu_Layer;\n";
   }
+  if (!GLContext::layered_rendering_support && bool(info.builtins_ & BuiltinBits::VIEWPORT_INDEX))
+  {
+    ss << "out int gpu_ViewportIndex;\n";
+  }
   if (bool(info.builtins_ & BuiltinBits::BARYCENTRIC_COORD)) {
     if (!GLContext::native_barycentric_support) {
       /* Disabled or unsupported. */
@@ -584,6 +588,13 @@ std::string GLShader::fragment_interface_declare(const ShaderCreateInfo &info) c
   for (const StageInterfaceInfo *iface : in_interfaces) {
     print_interface(ss, "in", *iface);
   }
+  if (!GLContext::layered_rendering_support && bool(info.builtins_ & BuiltinBits::LAYER)) {
+    ss << "#define gpu_Layer gl_Layer\n";
+  }
+  if (!GLContext::layered_rendering_support && bool(info.builtins_ & BuiltinBits::VIEWPORT_INDEX))
+  {
+    ss << "#define gpu_ViewportIndex gl_ViewportIndex\n";
+  }
   if (bool(info.builtins_ & BuiltinBits::BARYCENTRIC_COORD)) {
     if (!GLContext::native_barycentric_support) {
       ss << "flat in vec4 gpu_pos[3];\n";
@@ -736,6 +747,8 @@ std::string GLShader::workaround_geometry_shader_source_create(
 
   const bool do_layer_workaround = !GLContext::layered_rendering_support &&
                                    bool(info.builtins_ & BuiltinBits::LAYER);
+  const bool do_viewport_workaround = !GLContext::layered_rendering_support &&
+                                      bool(info.builtins_ & BuiltinBits::VIEWPORT_INDEX);
   const bool do_barycentric_workaround = !GLContext::native_barycentric_support &&
                                          bool(info.builtins_ & BuiltinBits::BARYCENTRIC_COORD);
 
@@ -752,6 +765,9 @@ std::string GLShader::workaround_geometry_shader_source_create(
   if (do_layer_workaround) {
     ss << "in int gpu_Layer[];\n";
   }
+  if (do_viewport_workaround) {
+    ss << "in int gpu_ViewportIndex[];\n";
+  }
   if (do_barycentric_workaround) {
     ss << "flat out vec4 gpu_pos[3];\n";
     ss << "smooth out vec3 gpu_BaryCoord;\n";
@@ -764,6 +780,9 @@ std::string GLShader::workaround_geometry_shader_source_create(
   if (do_layer_workaround) {
     ss << "  gl_Layer = gpu_Layer[0];\n";
   }
+  if (do_viewport_workaround) {
+    ss << "  gl_ViewportIndex = gpu_ViewportIndex[0];\n";
+  }
   if (do_barycentric_workaround) {
     ss << "  gpu_pos[0] = gl_in[0].gl_Position;\n";
     ss << "  gpu_pos[1] = gl_in[1].gl_Position;\n";
@@ -796,6 +815,9 @@ bool GLShader::do_geometry_shader_injection(const shader::ShaderCreateInfo *info
   if (!GLContext::layered_rendering_support && bool(builtins & BuiltinBits::LAYER)) {
     return true;
   }
+  if (!GLContext::layered_rendering_support && bool(builtins & BuiltinBits::VIEWPORT_INDEX)) {
+    return true;
+  }
   return false;
 }
 
@@ -853,8 +875,9 @@ static char *glsl_patch_default_get()
     STR_CONCAT(patch, slen, "#extension GL_ARB_shading_language_420pack: enable\n");
   }
   if (GLContext::layered_rendering_support) {
-    STR_CONCAT(patch, slen, "#extension GL_AMD_vertex_shader_layer: enable\n");
+    STR_CONCAT(patch, slen, "#extension GL_ARB_shader_viewport_layer_array: enable\n");
     STR_CONCAT(patch, slen, "#define gpu_Layer gl_Layer\n");
+    STR_CONCAT(patch, slen, "#define gpu_ViewportIndex gl_ViewportIndex\n");
   }
   if (GLContext::native_barycentric_support) {
     STR_CONCAT(patch, slen, "#extension GL_AMD_shader_explicit_vertex_parameter: enable\n");

source/blender/gpu/tests/framebuffer_test.cc

@@ -6,10 +6,13 @@
 
 #include "GPU_context.h"
 #include "GPU_framebuffer.h"
+#include "GPU_shader.h"
 #include "gpu_testing.hh"
 
 #include "BLI_math_vector.hh"
 
+#include "gpu_shader_create_info.hh"
+
 namespace blender::gpu::tests {
 
 static void test_framebuffer_clear_color_single_attachment()
@@ -248,4 +251,77 @@ static void test_framebuffer_cube()
 }
 GPU_TEST(framebuffer_cube)
 
+/* Effectively tests the same way EEVEE-Next shadows are rendered. */
+static void test_framebuffer_multi_viewport()
+{
+  using namespace gpu::shader;
+
+  GPU_render_begin();
+
+  const int2 size(4, 4);
+  const int layers = 256;
+  eGPUTextureUsage usage = GPU_TEXTURE_USAGE_ATTACHMENT | GPU_TEXTURE_USAGE_HOST_READ;
+  GPUTexture *texture = GPU_texture_create_2d_array(
+      __func__, UNPACK2(size), layers, 1, GPU_RG32I, usage, nullptr);
+
+  GPUFrameBuffer *framebuffer = GPU_framebuffer_create(__func__);
+  GPU_framebuffer_ensure_config(&framebuffer,
+                                {GPU_ATTACHMENT_NONE, GPU_ATTACHMENT_TEXTURE(texture)});
+  GPU_framebuffer_bind(framebuffer);
+
+  int viewport_rects[16][4];
+  for (int i = 0; i < 16; i++) {
+    viewport_rects[i][0] = i % 4;
+    viewport_rects[i][1] = i / 4;
+    viewport_rects[i][2] = 1;
+    viewport_rects[i][3] = 1;
+  }
+  GPU_framebuffer_multi_viewports_set(framebuffer, viewport_rects);
+
+  const float4 clear_color(0.0f);
+  GPU_framebuffer_clear_color(framebuffer, clear_color);
+
+  ShaderCreateInfo create_info("");
+  create_info.vertex_source("gpu_framebuffer_layer_viewport_test.glsl");
+  create_info.fragment_source("gpu_framebuffer_layer_viewport_test.glsl");
+  create_info.builtins(BuiltinBits::VIEWPORT_INDEX | BuiltinBits::LAYER);
+  create_info.fragment_out(0, Type::IVEC2, "out_value");
+
+  GPUShader *shader = GPU_shader_create_from_info(
+      reinterpret_cast<GPUShaderCreateInfo *>(&create_info));
+
+  /* TODO(fclem): remove this boilerplate. */
+  GPUVertFormat format{};
+  GPU_vertformat_attr_add(&format, "dummy", GPU_COMP_U32, 1, GPU_FETCH_INT);
+  GPUVertBuf *verts = GPU_vertbuf_create_with_format(&format);
+  GPU_vertbuf_data_alloc(verts, 3);
+  GPUBatch *batch = GPU_batch_create_ex(GPU_PRIM_TRIS, verts, nullptr, GPU_BATCH_OWNS_VBO);
+
+  GPU_batch_set_shader(batch, shader);
+
+  int tri_count = size.x * size.y * layers;
+  GPU_batch_draw_advanced(batch, 0, tri_count * 3, 0, 1);
+
+  GPU_batch_discard(batch);
+
+  GPU_finish();
+
+  int2 *read_data = static_cast<int2 *>(GPU_texture_read(texture, GPU_DATA_INT, 0));
+  for (auto layer : IndexRange(layers)) {
+    for (auto viewport : IndexRange(16)) {
+      int2 expected_color(layer, viewport);
+      int2 pixel_color = read_data[viewport + layer * 16];
+      EXPECT_EQ(pixel_color, expected_color);
+    }
+  }
+  MEM_freeN(read_data);
+
+  GPU_framebuffer_free(framebuffer);
+  GPU_texture_free(texture);
+  GPU_shader_free(shader);
+
+  GPU_render_end();
+}
+GPU_TEST(framebuffer_multi_viewport)
+
 }  // namespace blender::gpu::tests

source/blender/gpu/tests/shaders/gpu_framebuffer_layer_viewport_test.glsl

@@ -0,0 +1,23 @@
+
+#ifdef GPU_VERTEX_SHADER
+void main()
+{
+  /* Fullscreen triangle. */
+  int v = gl_VertexID % 3;
+  float x = -1.0 + float((v & 1) << 2);
+  float y = -1.0 + float((v & 2) << 1);
+  /* NOTE: Make it cover more than one viewport to test default scissors. */
+  gl_Position = vec4(x * 2.0, y * 2.0, 1.0, 1.0);
+
+  int index = gl_VertexID / 3;
+  gpu_ViewportIndex = index % 16;
+  gpu_Layer = index / 16;
+}
+#endif
+
+#ifdef GPU_FRAGMENT_SHADER
+void main()
+{
+  out_value = ivec2(gpu_Layer, gpu_ViewportIndex);
+}
+#endif

source/blender/gpu/vulkan/vk_command_buffer.cc

@@ -376,7 +376,7 @@ void VKCommandBuffer::ensure_active_framebuffer()
     render_pass_begin_info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
     render_pass_begin_info.renderPass = state.framebuffer_->vk_render_pass_get();
     render_pass_begin_info.framebuffer = state.framebuffer_->vk_framebuffer_get();
-    render_pass_begin_info.renderArea = state.framebuffer_->vk_render_area_get();
+    render_pass_begin_info.renderArea = state.framebuffer_->vk_render_areas_get()[0];
     /* We don't use clear ops, but vulkan wants to have at least one. */
     VkClearValue clear_value = {};
     render_pass_begin_info.clearValueCount = 1;

source/blender/gpu/vulkan/vk_framebuffer.cc

@@ -71,52 +71,53 @@ void VKFrameBuffer::bind(bool /*enabled_srgb*/)
   context.activate_framebuffer(*this);
 }
 
-VkViewport VKFrameBuffer::vk_viewport_get() const
+Array<VkViewport, 16> VKFrameBuffer::vk_viewports_get() const
 {
-  VkViewport viewport;
-  int viewport_rect[4];
-  viewport_get(viewport_rect);
+  Array<VkViewport, 16> viewports(this->multi_viewport_ ? GPU_MAX_VIEWPORTS : 1);
 
-  viewport.x = viewport_rect[0];
-  viewport.y = viewport_rect[1];
-  viewport.width = viewport_rect[2];
-  viewport.height = viewport_rect[3];
-  viewport.minDepth = 0.0f;
-  viewport.maxDepth = 1.0f;
-
-  /*
-   * Vulkan has origin to the top left, Blender bottom left. We counteract this by using a negative
-   * viewport when flip_viewport_ is set. This flips the viewport making any draw/blit use the
-   * correct orientation.
-   */
-  if (flip_viewport_) {
-    viewport.y = height_ - viewport_rect[1];
-    viewport.height = -viewport_rect[3];
+  int index = 0;
+  for (VkViewport &viewport : viewports) {
+    viewport.x = viewport_[index][0];
+    viewport.y = viewport_[index][1];
+    viewport.width = viewport_[index][2];
+    viewport.height = viewport_[index][3];
+    viewport.minDepth = 0.0f;
+    viewport.maxDepth = 1.0f;
+    /*
+     * Vulkan has origin to the top left, Blender bottom left. We counteract this by using a
+     * negative viewport when flip_viewport_ is set. This flips the viewport making any draw/blit
+     * use the correct orientation.
+     */
+    if (flip_viewport_) {
+      viewport.y = height_ - viewport_[index][1];
+      viewport.height = -viewport_[index][3];
+    }
+    index++;
   }
-
-  return viewport;
+  return viewports;
 }
 
-VkRect2D VKFrameBuffer::vk_render_area_get() const
+Array<VkRect2D, 16> VKFrameBuffer::vk_render_areas_get() const
 {
-  VkRect2D render_area = {};
+  Array<VkRect2D, 16> render_areas(this->multi_viewport_ ? GPU_MAX_VIEWPORTS : 1);
 
-  if (scissor_test_get()) {
-    int scissor_rect[4];
-    scissor_get(scissor_rect);
-    render_area.offset.x = scissor_rect[0];
-    render_area.offset.y = scissor_rect[1];
-    render_area.extent.width = scissor_rect[2];
-    render_area.extent.height = scissor_rect[3];
+  for (VkRect2D &render_area : render_areas) {
+    if (scissor_test_get()) {
+      int scissor_rect[4];
+      scissor_get(scissor_rect);
+      render_area.offset.x = scissor_rect[0];
+      render_area.offset.y = scissor_rect[1];
+      render_area.extent.width = scissor_rect[2];
+      render_area.extent.height = scissor_rect[3];
+    }
+    else {
+      render_area.offset.x = 0;
+      render_area.offset.y = 0;
+      render_area.extent.width = width_;
+      render_area.extent.height = height_;
+    }
   }
-  else {
-    render_area.offset.x = 0;
-    render_area.offset.y = 0;
-    render_area.extent.width = width_;
-    render_area.extent.height = height_;
-  }
-
-  return render_area;
+  return render_areas;
 }
 
 bool VKFrameBuffer::check(char /*err_out*/[256])
@@ -170,7 +171,7 @@ void VKFrameBuffer::clear(const Vector<VkClearAttachment> &attachments) const
     return;
   }
   VkClearRect clear_rect = {};
-  clear_rect.rect = vk_render_area_get();
+  clear_rect.rect = vk_render_areas_get()[0];
   clear_rect.baseArrayLayer = 0;
   clear_rect.layerCount = 1;
 

source/blender/gpu/vulkan/vk_framebuffer.hh

@@ -8,6 +8,7 @@
 
 #pragma once
 
+#include "BLI_array.hh"
 #include "BLI_math_vector.hh"
 #include "BLI_span.hh"
 #include "BLI_vector.hh"
@@ -107,8 +108,8 @@ class VKFrameBuffer : public FrameBuffer {
     BLI_assert(vk_render_pass_ != VK_NULL_HANDLE);
     return vk_render_pass_;
   }
-  VkViewport vk_viewport_get() const;
-  VkRect2D vk_render_area_get() const;
+  Array<VkViewport, 16> vk_viewports_get() const;
+  Array<VkRect2D, 16> vk_render_areas_get() const;
   VkImage vk_image_get() const
   {
     BLI_assert(vk_image_ != VK_NULL_HANDLE);

source/blender/gpu/vulkan/vk_pipeline.cc

@@ -164,12 +164,12 @@ void VKPipeline::finalize(VKContext &context,
   /* Viewport state. */
   VkPipelineViewportStateCreateInfo viewport_state = {};
   viewport_state.sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
-  VkViewport viewport = framebuffer.vk_viewport_get();
-  viewport_state.pViewports = &viewport;
-  viewport_state.viewportCount = 1;
-  VkRect2D scissor = framebuffer.vk_render_area_get();
-  viewport_state.pScissors = &scissor;
-  viewport_state.scissorCount = 1;
+  Array<VkViewport, 16> viewports = framebuffer.vk_viewports_get();
+  viewport_state.pViewports = &viewports[0];
+  viewport_state.viewportCount = viewports.size();
+  Array<VkRect2D, 16> scissors = framebuffer.vk_render_areas_get();
+  viewport_state.pScissors = &scissors[0];
+  viewport_state.scissorCount = scissors.size();
   pipeline_create_info.pViewportState = &viewport_state;
 
   /* Multi-sample state. */

source/blender/gpu/vulkan/vk_shader.cc

@@ -500,6 +500,11 @@ static char *glsl_patch_get()
 
   STR_CONCAT(patch, slen, "#define gl_InstanceID gpu_InstanceIndex\n");
 
+  /* TODO(fclem): This creates a validation error and should be already part of Vulkan 1.2. */
+  STR_CONCAT(patch, slen, "#extension GL_ARB_shader_viewport_layer_array: enable\n");
+  STR_CONCAT(patch, slen, "#define gpu_Layer gl_Layer\n");
+  STR_CONCAT(patch, slen, "#define gpu_ViewportIndex gl_ViewportIndex\n");
+
   STR_CONCAT(patch, slen, "#define DFDX_SIGN 1.0\n");
   STR_CONCAT(patch, slen, "#define DFDY_SIGN 1.0\n");
 
@@ -526,6 +531,7 @@ Vector<uint32_t> VKShader::compile_glsl_to_spirv(Span<const char *> sources,
   shaderc::Compiler &compiler = backend.get_shaderc_compiler();
   shaderc::CompileOptions options;
   options.SetOptimizationLevel(shaderc_optimization_level_performance);
+  options.SetTargetEnvironment(shaderc_target_env_vulkan, shaderc_env_version_vulkan_1_2);
   if (G.debug & G_DEBUG_GPU_RENDERDOC) {
     options.SetOptimizationLevel(shaderc_optimization_level_zero);
     options.SetGenerateDebugInfo();