add shader quad control sample demonstrating VK_KHR_shader_quad_control features.

Author: gpx1000

antora/modules/ROOT/nav.adoc

@@ -86,6 +86,7 @@
 ** xref:samples/extensions/ray_tracing_reflection/README.adoc[Ray tracing reflection]
 ** xref:samples/extensions/ray_tracing_position_fetch/README.adoc[Ray tracing position fetch]
 ** xref:samples/extensions/shader_object/README.adoc[Shader Object]
+** xref:samples/extensions/shader_quad_control/README.adoc[Shader quad control]
 ** xref:samples/extensions/shader_debugprintf/README.adoc[Shader Debug Printf]
 ** xref:samples/extensions/sparse_image/README.adoc[Sparse Image]
 ** xref:samples/extensions/synchronization_2/README.adoc[Synchronization 2]

framework/vulkan_type_mapping.h

@@ -162,6 +162,12 @@ struct HPPType<VkPhysicalDeviceFragmentShaderBarycentricFeaturesKHR>
 	using Type = vk::PhysicalDeviceFragmentShaderBarycentricFeaturesKHR;
 };
 
+template <>
+struct HPPType<VkPhysicalDeviceShaderQuadControlFeaturesKHR>
+{
+	using Type = vk::PhysicalDeviceShaderQuadControlFeaturesKHR;
+};
+
 template <>
 struct HPPType<VkPhysicalDeviceFragmentShadingRateFeaturesKHR>
 {

samples/extensions/README.adoc

@@ -1,5 +1,5 @@
 ////
-- Copyright (c) 2021-2024, The Khronos Group
+- Copyright (c) 2021-2025, The Khronos Group
 -
 - SPDX-License-Identifier: Apache-2.0
 -
@@ -302,3 +302,9 @@ Demonstrate the use of the host image extension to directly copy from a host buf
 *Extensions:* https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_EXT_extended_dynamic_state3.html[`VK_EXT_line_rasterization`], https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_EXT_extended_dynamic_state3.html[`VK_EXT_extended_dynamic_state3`]
 
 Demonstrate how to use dynamic multisample rasterization (MSAA)
+
+=== xref:./{extension_samplespath}shader_quad_control/README.adoc[Shader quad control]
+
+*Extension*: https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_KHR_shader_quad_control.html[`VK_KHR_shader_quad_control`]
+
+Demonstrates quad‑scope operations in fragment shaders, such as broadcasting values within a 2x2 quad, and explains the `layout(full_quads)` and `layout(quad_derivatives)` execution modes.

samples/extensions/shader_quad_control/CMakeLists.txt

@@ -0,0 +1,29 @@
+# Copyright (c) 2025, Holochip Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 the "License";
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+get_filename_component(FOLDER_NAME ${CMAKE_CURRENT_LIST_DIR} NAME)
+get_filename_component(PARENT_DIR ${CMAKE_CURRENT_LIST_DIR} PATH)
+get_filename_component(CATEGORY_NAME ${PARENT_DIR} NAME)
+
+add_sample(
+    ID ${FOLDER_NAME}
+    CATEGORY ${CATEGORY_NAME}
+    AUTHOR "Holochip"
+    NAME "Shader quad control"
+    DESCRIPTION "Demonstrates VK_KHR_shader_quad_control with a simple fullscreen draw using quad vote ops."
+    SHADER_FILES_GLSL
+        "shader_quad_control/glsl/quad_control.vert"
+        "shader_quad_control/glsl/quad_control.frag")

samples/extensions/shader_quad_control/README.adoc

@@ -0,0 +1,80 @@
+////
+- Copyright (c) 2025, Holochip Inc.
+-
+- SPDX-License-Identifier: Apache-2.0
+-
+- Licensed under the Apache License, Version 2.0 the "License";
+- you may not use this file except in compliance with the License.
+- You may obtain a copy of the License at
+-
+-     http://www.apache.org/licenses/LICENSE-2.0
+-
+- Unless required by applicable law or agreed to in writing, software
+- distributed under the License is distributed on an "AS IS" BASIS,
+- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+- See the License for the specific language governing permissions and
+- limitations under the License.
+-
+////
+
+= Shader quad control (VK_KHR_shader_quad_control)
+
+This sample demonstrates VK_KHR_shader_quad_control in a minimal graphics pipeline.
+It renders a full‑screen triangle and uses quad‑scope operations in the fragment shader to
+broadcast values within a 2x2 pixel quad. This produces a characteristic “blocky” 2x2 pattern,
+clearly showing how quad operations affect shading.
+
+== What is shader quad control?
+VK_KHR_shader_quad_control exposes SPIR‑V and shading language capabilities that operate at the
+scope of a fragment “quad” – the 2x2 group of fragment shader invocations that participate in
+coherent derivative calculation. The extension adds:
+
+- A shader execution mode to control quad formation: `layout(full_quads)` or `layout(quad_derivatives)`.
+- Built‑ins and functions to communicate within a quad, like `subgroupQuadBroadcast(...)`, and vote
+  operations `subgroupQuadAll(...)` / `subgroupQuadAny(...)`.
+
+Typical uses include:
+
+- Stabilizing derivatives, LOD selection, and gradient‑sensitive operations across the 2x2 quad.
+- Sharing values between lanes in a quad without using shared memory.
+
+== What this sample does
+- Creates a simple graphics pipeline (full‑screen triangle, no descriptors).
+- The fragment shader enables `GL_EXT_shader_quad_control` and declares `layout(full_quads) in;`.
+- It calls `subgroupQuadBroadcast(vUV, 0)` to broadcast the top‑left lane’s interpolant to the
+  whole quad, so each 2x2 block shows one color based on the leader lane.
+
+This minimal approach keeps focus on the quad control feature rather than complex rendering.
+
+== Required extensions and features
+To run this sample, the device must support `VK_KHR_shader_quad_control`.
+
+No descriptors or additional states are required for this minimal demo. The sample uses the
+framework’s default render pass and a basic pipeline configuration.
+
+== Fragment shader
+The fragment shader uses quad control to broadcast a varying from the quad leader:
+
+[source,glsl]
+----
+#version 450
+#extension GL_EXT_shader_quad_control : require
+
+layout(full_quads) in;                    // Control quad scope
+layout(location = 0) in vec2 vUV;         // Interpolated UV from VS
+layout(location = 0) out vec4 outColor;
+
+void main()
+{
+    vec2 uv_leader = subgroupQuadBroadcast(vUV, 0); // From top-left of the 2x2 quad
+    outColor = vec4(uv_leader, 0.5, 1.0);
+}
+----
+
+Switching to `layout(quad_derivatives) in;` would instead ensure that implicit derivatives are
+computed in a quad‑coherent way (useful if you perform gradient operations like texture LODs).
+This sample focuses on the broadcasting operation for clarity.
+
+== Specification
+- Vulkan: https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_KHR_shader_quad_control.html[VK_KHR_shader_quad_control]
+- GLSL: https://github.com/KhronosGroup/GLSL/blob/main/extensions/ext/GLSL_EXT_shader_quad_control.txt[GLSL_EXT_shader_quad_control]

samples/extensions/shader_quad_control/shader_quad_control.cpp

@@ -0,0 +1,190 @@
+/* Copyright (c) 2025, Holochip Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 the "License";
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "shader_quad_control.h"
+
+ShaderQuadControl::ShaderQuadControl()
+{
+	title = "Shader quad control";
+	set_api_version(VK_API_VERSION_1_2);
+
+	add_instance_extension(VK_KHR_GET_PHYSICAL_DEVICE_PROPERTIES_2_EXTENSION_NAME);
+	// VK_KHR_shader_quad_control requires VK_KHR_shader_maximal_reconvergence per spec
+	add_device_extension(VK_KHR_SHADER_MAXIMAL_RECONVERGENCE_EXTENSION_NAME);
+	add_device_extension(VK_KHR_SHADER_QUAD_CONTROL_EXTENSION_NAME);
+}
+
+ShaderQuadControl::~ShaderQuadControl()
+{
+	if (has_device())
+	{
+		if (pipeline != VK_NULL_HANDLE)
+		{
+			vkDestroyPipeline(get_device().get_handle(), pipeline, nullptr);
+		}
+		if (pipeline_layout != VK_NULL_HANDLE)
+		{
+			vkDestroyPipelineLayout(get_device().get_handle(), pipeline_layout, nullptr);
+		}
+	}
+}
+
+bool ShaderQuadControl::prepare(const vkb::ApplicationOptions &options)
+{
+	if (!ApiVulkanSample::prepare(options))
+	{
+		return false;
+	}
+
+	create_pipeline_layout();
+	create_pipeline();
+	build_command_buffers();
+
+	prepared = true;
+	return true;
+}
+
+void ShaderQuadControl::request_gpu_features(vkb::core::PhysicalDeviceC &gpu)
+{
+	REQUEST_REQUIRED_FEATURE(gpu, VkPhysicalDeviceShaderQuadControlFeaturesKHR, shaderQuadControl);
+}
+
+void ShaderQuadControl::create_pipeline_layout()
+{
+	VkPipelineLayoutCreateInfo pipeline_layout_ci{VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO};
+	VK_CHECK(vkCreatePipelineLayout(get_device().get_handle(), &pipeline_layout_ci, nullptr, &pipeline_layout));
+}
+
+void ShaderQuadControl::create_pipeline()
+{
+	std::array<VkPipelineShaderStageCreateInfo, 2> stages{};
+	stages[0] = load_shader("shader_quad_control/glsl/quad_control.vert.spv", VK_SHADER_STAGE_VERTEX_BIT);
+	stages[1] = load_shader("shader_quad_control/glsl/quad_control.frag.spv", VK_SHADER_STAGE_FRAGMENT_BIT);
+
+	VkPipelineVertexInputStateCreateInfo vertex_input{VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO};
+
+	VkPipelineInputAssemblyStateCreateInfo input_assembly{VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO};
+	input_assembly.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+
+	VkPipelineViewportStateCreateInfo viewport_state{VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO};
+	viewport_state.viewportCount = 1;
+	viewport_state.scissorCount  = 1;
+
+	VkPipelineRasterizationStateCreateInfo raster{VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO};
+	raster.polygonMode = VK_POLYGON_MODE_FILL;
+	raster.cullMode    = VK_CULL_MODE_NONE;
+	raster.frontFace   = VK_FRONT_FACE_COUNTER_CLOCKWISE;
+	raster.lineWidth   = 1.0f;
+
+	VkPipelineMultisampleStateCreateInfo msaa{VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO};
+	msaa.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
+
+	VkPipelineDepthStencilStateCreateInfo depth_stencil{VK_STRUCTURE_TYPE_PIPELINE_DEPTH_STENCIL_STATE_CREATE_INFO};
+	depth_stencil.depthTestEnable  = VK_FALSE;
+	depth_stencil.depthWriteEnable = VK_FALSE;
+
+	VkPipelineColorBlendAttachmentState color_blend_attachment{};
+	color_blend_attachment.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
+
+	VkPipelineColorBlendStateCreateInfo color_blend{VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO};
+	color_blend.attachmentCount = 1;
+	color_blend.pAttachments    = &color_blend_attachment;
+
+	std::array<VkDynamicState, 2>    dynamic_states{VK_DYNAMIC_STATE_VIEWPORT, VK_DYNAMIC_STATE_SCISSOR};
+	VkPipelineDynamicStateCreateInfo dynamic_state{VK_STRUCTURE_TYPE_PIPELINE_DYNAMIC_STATE_CREATE_INFO};
+	dynamic_state.dynamicStateCount = static_cast<uint32_t>(dynamic_states.size());
+	dynamic_state.pDynamicStates    = dynamic_states.data();
+
+	VkGraphicsPipelineCreateInfo pipeline_ci{VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO};
+	pipeline_ci.stageCount          = static_cast<uint32_t>(stages.size());
+	pipeline_ci.pStages             = stages.data();
+	pipeline_ci.pVertexInputState   = &vertex_input;
+	pipeline_ci.pInputAssemblyState = &input_assembly;
+	pipeline_ci.pViewportState      = &viewport_state;
+	pipeline_ci.pRasterizationState = &raster;
+	pipeline_ci.pMultisampleState   = &msaa;
+	pipeline_ci.pDepthStencilState  = &depth_stencil;
+	pipeline_ci.pColorBlendState    = &color_blend;
+	pipeline_ci.pDynamicState       = &dynamic_state;
+	pipeline_ci.layout              = pipeline_layout;
+	pipeline_ci.renderPass          = render_pass;
+
+	VK_CHECK(vkCreateGraphicsPipelines(get_device().get_handle(), VK_NULL_HANDLE, 1, &pipeline_ci, nullptr, &pipeline));
+}
+
+void ShaderQuadControl::build_command_buffers()
+{
+	VkCommandBufferBeginInfo begin_info{VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO};
+	VkClearValue             clear_values[2];
+	clear_values[0].color        = {{0.0f, 0.0f, 0.0f, 1.0f}};
+	clear_values[1].depthStencil = {1.0f, 0};
+
+	VkRenderPassBeginInfo render_pass_begin{VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO};
+	render_pass_begin.renderPass        = render_pass;
+	render_pass_begin.renderArea.offset = {0, 0};
+	render_pass_begin.renderArea.extent = get_render_context().get_surface_extent();
+	render_pass_begin.clearValueCount   = 2;
+	render_pass_begin.pClearValues      = clear_values;
+
+	for (size_t i = 0; i < draw_cmd_buffers.size(); i++)
+	{
+		render_pass_begin.framebuffer = framebuffers[i];
+		VK_CHECK(vkBeginCommandBuffer(draw_cmd_buffers[i], &begin_info));
+
+		vkCmdBeginRenderPass(draw_cmd_buffers[i], &render_pass_begin, VK_SUBPASS_CONTENTS_INLINE);
+
+		VkViewport viewport{};
+		viewport.width    = static_cast<float>(get_render_context().get_surface_extent().width);
+		viewport.height   = static_cast<float>(get_render_context().get_surface_extent().height);
+		viewport.minDepth = 0.0f;
+		viewport.maxDepth = 1.0f;
+		vkCmdSetViewport(draw_cmd_buffers[i], 0, 1, &viewport);
+
+		VkRect2D scissor{{0, 0}, get_render_context().get_surface_extent()};
+		vkCmdSetScissor(draw_cmd_buffers[i], 0, 1, &scissor);
+
+		vkCmdBindPipeline(draw_cmd_buffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline);
+		vkCmdDraw(draw_cmd_buffers[i], 3, 1, 0, 0);
+
+		draw_ui(draw_cmd_buffers[i]);
+		vkCmdEndRenderPass(draw_cmd_buffers[i]);
+		VK_CHECK(vkEndCommandBuffer(draw_cmd_buffers[i]));
+	}
+}
+
+void ShaderQuadControl::draw()
+{
+	prepare_frame();
+	submit_info.commandBufferCount = 1;
+	submit_info.pCommandBuffers    = &draw_cmd_buffers[current_buffer];
+	VK_CHECK(vkQueueSubmit(queue, 1, &submit_info, VK_NULL_HANDLE));
+	submit_frame();
+}
+
+void ShaderQuadControl::render(float)
+{
+	if (!prepared)
+	{
+		return;
+	}
+	draw();
+}
+
+std::unique_ptr<vkb::VulkanSampleC> create_shader_quad_control()
+{
+	return std::make_unique<ShaderQuadControl>();
+}

samples/extensions/shader_quad_control/shader_quad_control.h

@@ -0,0 +1,42 @@
+/* Copyright (c) 2025, Holochip Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 the "License";
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "api_vulkan_sample.h"
+
+class ShaderQuadControl : public ApiVulkanSample
+{
+  public:
+	ShaderQuadControl();
+	~ShaderQuadControl() override;
+
+	bool prepare(const vkb::ApplicationOptions &options) override;
+	void build_command_buffers() override;
+	void request_gpu_features(vkb::core::PhysicalDeviceC &gpu) override;
+	void render(float delta_time) override;
+
+  private:
+	void create_pipeline_layout();
+	void create_pipeline();
+	void draw();
+
+	VkPipeline       pipeline{VK_NULL_HANDLE};
+	VkPipelineLayout pipeline_layout{VK_NULL_HANDLE};
+};
+
+std::unique_ptr<vkb::VulkanSampleC> create_shader_quad_control();