monado/src/xrt/compositor/render/comp_rendering.c

// Copyright 2019-2020, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  The NEW compositor rendering code header.
 * @author Lubosz Sarnecki <lubosz.sarnecki@collabora.com>
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @ingroup comp_main
 */

#include "main/comp_compositor.h"
#include "render/comp_render.h"

#include <stdio.h>


/*
 *
 * Common helpers
 *
 */

#define C(c)                                                                   \
	do {                                                                   \
		VkResult ret = c;                                              \
		if (ret != VK_SUCCESS) {                                       \
			return false;                                          \
		}                                                              \
	} while (false)

#define D(TYPE, thing)                                                         \
	if (thing != VK_NULL_HANDLE) {                                         \
		vk->vkDestroy##TYPE(vk->device, thing, NULL);                  \
		thing = VK_NULL_HANDLE;                                        \
	}

#define DD(pool, thing)                                                        \
	if (thing != VK_NULL_HANDLE) {                                         \
		free_descriptor_set(vk, pool, thing);                          \
		thing = VK_NULL_HANDLE;                                        \
	}

static VkResult
create_external_render_pass(struct vk_bundle *vk,
                            VkFormat format,
                            VkRenderPass *out_render_pass)
{
	VkResult ret;

	VkAttachmentDescription attachments[1] = {
	    {
	        .format = format,
	        .samples = VK_SAMPLE_COUNT_1_BIT,
	        .loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR,
	        .storeOp = VK_ATTACHMENT_STORE_OP_STORE,
	        .stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE,
	        .stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE,
	        .initialLayout = VK_IMAGE_LAYOUT_UNDEFINED,
	        .finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
	    },
	};

	VkAttachmentReference color_reference = {
	    .attachment = 0,
	    .layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL,
	};

	VkSubpassDescription subpasses[1] = {
	    {
	        .pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS,
	        .inputAttachmentCount = 0,
	        .pInputAttachments = NULL,
	        .colorAttachmentCount = 1,
	        .pColorAttachments = &color_reference,
	        .pResolveAttachments = NULL,
	        .pDepthStencilAttachment = NULL,
	        .preserveAttachmentCount = 0,
	        .pPreserveAttachments = NULL,
	    },
	};

	VkSubpassDependency dependencies[1] = {
	    {
	        .srcSubpass = VK_SUBPASS_EXTERNAL,
	        .dstSubpass = 0,
	        .srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
	        .dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
	        .srcAccessMask = 0,
	        .dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT |
	                         VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT,
	    },
	};

	VkRenderPassCreateInfo render_pass_info = {
	    .sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO,
	    .attachmentCount = ARRAY_SIZE(attachments),
	    .pAttachments = attachments,
	    .subpassCount = ARRAY_SIZE(subpasses),
	    .pSubpasses = subpasses,
	    .dependencyCount = ARRAY_SIZE(dependencies),
	    .pDependencies = dependencies,
	};

	VkRenderPass render_pass = VK_NULL_HANDLE;
	ret = vk->vkCreateRenderPass(vk->device,        //
	                             &render_pass_info, //
	                             NULL,              //
	                             &render_pass);     //
	if (ret != VK_SUCCESS) {
		VK_ERROR(vk, "vkCreateRenderPass failed: %s",
		         vk_result_string(ret));
		return ret;
	}

	*out_render_pass = render_pass;

	return VK_SUCCESS;
}

static VkResult
create_descriptor_set(struct vk_bundle *vk,
                      VkDescriptorPool descriptor_pool,
                      VkDescriptorSetLayout descriptor_layout,
                      VkDescriptorSet *out_descriptor_set)
{
	VkResult ret;

	VkDescriptorSetAllocateInfo alloc_info = {
	    .sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO,
	    .descriptorPool = descriptor_pool,
	    .descriptorSetCount = 1,
	    .pSetLayouts = &descriptor_layout,
	};

	VkDescriptorSet descriptor_set = VK_NULL_HANDLE;
	ret = vk->vkAllocateDescriptorSets(vk->device,       //
	                                   &alloc_info,      //
	                                   &descriptor_set); //
	if (ret != VK_SUCCESS) {
		VK_DEBUG(vk, "vkAllocateDescriptorSets failed: %s",
		         vk_result_string(ret));
		return ret;
	}

	*out_descriptor_set = descriptor_set;

	return VK_SUCCESS;
}

static void
free_descriptor_set(struct vk_bundle *vk,
                    VkDescriptorPool descriptor_pool,
                    VkDescriptorSet descriptor_set)
{
	VkResult ret;


	ret = vk->vkFreeDescriptorSets(vk->device,       //
	                               descriptor_pool,  // descriptorPool
	                               1,                // descriptorSetCount
	                               &descriptor_set); // pDescriptorSets
	if (ret != VK_SUCCESS) {
		VK_DEBUG(vk, "vkFreeDescriptorSets failed: %s",
		         vk_result_string(ret));
	}
}

static VkResult
create_framebuffer(struct vk_bundle *vk,
                   VkImageView image_view,
                   VkRenderPass render_pass,
                   uint32_t width,
                   uint32_t height,
                   VkFramebuffer *out_external_framebuffer)
{
	VkResult ret;

	VkImageView attachments[1] = {image_view};

	VkFramebufferCreateInfo frame_buffer_info = {
	    .sType = VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO,
	    .renderPass = render_pass,
	    .attachmentCount = ARRAY_SIZE(attachments),
	    .pAttachments = attachments,
	    .width = width,
	    .height = height,
	    .layers = 1,
	};

	VkFramebuffer framebuffer = VK_NULL_HANDLE;
	ret = vk->vkCreateFramebuffer(vk->device,         //
	                              &frame_buffer_info, //
	                              NULL,               //
	                              &framebuffer);      //
	if (ret != VK_SUCCESS) {
		VK_ERROR(vk, "vkCreateFramebuffer failed: %s",
		         vk_result_string(ret));
		return ret;
	}

	*out_external_framebuffer = framebuffer;

	return VK_SUCCESS;
}

static VkResult
create_command_buffer(struct vk_bundle *vk, VkCommandBuffer *out_cmd)
{
	VkResult ret;

	VkCommandBufferAllocateInfo cmd_buffer_info = {
	    .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
	    .commandPool = vk->cmd_pool,
	    .level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
	    .commandBufferCount = 1,
	};

	VkCommandBuffer cmd = VK_NULL_HANDLE;

	os_mutex_lock(&vk->cmd_pool_mutex);

	ret = vk->vkAllocateCommandBuffers(vk->device,       //
	                                   &cmd_buffer_info, //
	                                   &cmd);            //

	os_mutex_unlock(&vk->cmd_pool_mutex);

	if (ret != VK_SUCCESS) {
		VK_ERROR(vk, "vkCreateFramebuffer failed: %s",
		         vk_result_string(ret));
		return ret;
	}

	*out_cmd = cmd;

	return VK_SUCCESS;
}

static VkResult
begin_command_buffer(struct vk_bundle *vk, VkCommandBuffer command_buffer)
{
	VkResult ret;

	VkCommandBufferBeginInfo command_buffer_info = {
	    .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
	};

	ret = vk->vkBeginCommandBuffer(command_buffer, &command_buffer_info);
	if (ret != VK_SUCCESS) {
		VK_ERROR(vk, "vkBeginCommandBuffer failed: %s",
		         vk_result_string(ret));
		return ret;
	}

	return VK_SUCCESS;
}

static void
begin_render_pass(struct vk_bundle *vk,
                  VkCommandBuffer command_buffer,
                  VkRenderPass render_pass,
                  VkFramebuffer framebuffer,
                  uint32_t width,
                  uint32_t height)
{
	VkClearValue clear_color[1] = {{
	    .color = {.float32 = {0.0f, 0.0f, 0.0f, 0.0f}},
	}};

	VkRenderPassBeginInfo render_pass_begin_info = {
	    .sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO,
	    .renderPass = render_pass,
	    .framebuffer = framebuffer,
	    .renderArea =
	        {
	            .offset =
	                {
	                    .x = 0,
	                    .y = 0,
	                },
	            .extent =
	                {
	                    .width = width,
	                    .height = height,
	                },
	        },
	    .clearValueCount = ARRAY_SIZE(clear_color),
	    .pClearValues = clear_color,
	};

	vk->vkCmdBeginRenderPass(command_buffer, &render_pass_begin_info,
	                         VK_SUBPASS_CONTENTS_INLINE);
}


/*
 *
 * Mesh
 *
 */

static VkResult
create_mesh_pipeline(struct vk_bundle *vk,
                     VkRenderPass render_pass,
                     VkPipelineLayout pipeline_layout,
                     VkPipelineCache pipeline_cache,
                     uint32_t src_binding,
                     uint32_t mesh_total_num_indices,
                     uint32_t mesh_stride,
                     VkShaderModule mesh_vert,
                     VkShaderModule mesh_frag,
                     VkPipeline *out_mesh_pipeline)
{
	VkResult ret;

	// Might be changed to line for debugging.
	VkPolygonMode polygonMode = VK_POLYGON_MODE_FILL;

	// Do we use triangle strips or triangles with indices.
	VkPrimitiveTopology topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
	if (mesh_total_num_indices > 0) {
		topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_STRIP;
	}

	VkPipelineInputAssemblyStateCreateInfo input_assembly_state = {
	    .sType =
	        VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO,
	    .topology = topology,
	    .primitiveRestartEnable = VK_FALSE,
	};

	VkPipelineRasterizationStateCreateInfo rasterization_state = {
	    .sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO,
	    .depthClampEnable = VK_FALSE,
	    .rasterizerDiscardEnable = VK_FALSE,
	    .polygonMode = polygonMode,
	    .cullMode = VK_CULL_MODE_BACK_BIT,
	    .frontFace = VK_FRONT_FACE_CLOCKWISE,
	    .lineWidth = 1.0f,
	};

	VkPipelineColorBlendAttachmentState blend_attachment_state = {
	    .blendEnable = VK_FALSE,
	    .colorWriteMask = 0xf,
	};

	VkPipelineColorBlendStateCreateInfo color_blend_state = {
	    .sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO,
	    .attachmentCount = 1,
	    .pAttachments = &blend_attachment_state,
	};

	VkPipelineDepthStencilStateCreateInfo depth_stencil_state = {
	    .sType = VK_STRUCTURE_TYPE_PIPELINE_DEPTH_STENCIL_STATE_CREATE_INFO,
	    .depthTestEnable = VK_TRUE,
	    .depthWriteEnable = VK_TRUE,
	    .depthCompareOp = VK_COMPARE_OP_LESS_OR_EQUAL,
	    .front =
	        {
	            .compareOp = VK_COMPARE_OP_ALWAYS,
	        },
	    .back =
	        {
	            .compareOp = VK_COMPARE_OP_ALWAYS,
	        },
	};

	VkPipelineViewportStateCreateInfo viewport_state = {
	    .sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO,
	    .viewportCount = 1,
	    .scissorCount = 1,
	};

	VkPipelineMultisampleStateCreateInfo multisample_state = {
	    .sType = VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO,
	    .rasterizationSamples = VK_SAMPLE_COUNT_1_BIT,
	};

	VkDynamicState dynamic_states[] = {
	    VK_DYNAMIC_STATE_VIEWPORT,
	    VK_DYNAMIC_STATE_SCISSOR,
	};

	VkPipelineDynamicStateCreateInfo dynamic_state = {
	    .sType = VK_STRUCTURE_TYPE_PIPELINE_DYNAMIC_STATE_CREATE_INFO,
	    .dynamicStateCount = ARRAY_SIZE(dynamic_states),
	    .pDynamicStates = dynamic_states,
	};

	// clang-format off
	VkVertexInputAttributeDescription vertex_input_attribute_descriptions[2] = {
	    {
	        .binding = src_binding,
	        .location = 0,
	        .format = VK_FORMAT_R32G32B32A32_SFLOAT,
	        .offset = 0,
	    },
	    {
	        .binding = src_binding,
	        .location = 1,
	        .format = VK_FORMAT_R32G32B32A32_SFLOAT,
	        .offset = 16,
	    },
	};

	VkVertexInputBindingDescription vertex_input_binding_description[1] = {
	    {
	        .binding = src_binding,
	        .inputRate = VK_VERTEX_INPUT_RATE_VERTEX,
	        .stride = mesh_stride,
	    },
	};

	VkPipelineVertexInputStateCreateInfo vertex_input_state = {
	    .sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO,
	    .vertexAttributeDescriptionCount = ARRAY_SIZE(vertex_input_attribute_descriptions),
	    .pVertexAttributeDescriptions = vertex_input_attribute_descriptions,
	    .vertexBindingDescriptionCount = ARRAY_SIZE(vertex_input_binding_description),
	    .pVertexBindingDescriptions = vertex_input_binding_description,
	};
	// clang-format on

	VkPipelineShaderStageCreateInfo shader_stages[2] = {
	    {
	        .sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO,
	        .stage = VK_SHADER_STAGE_VERTEX_BIT,
	        .module = mesh_vert,
	        .pName = "main",
	    },
	    {
	        .sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO,
	        .stage = VK_SHADER_STAGE_FRAGMENT_BIT,
	        .module = mesh_frag,
	        .pName = "main",
	    },
	};

	VkGraphicsPipelineCreateInfo pipeline_info = {
	    .sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO,
	    .stageCount = ARRAY_SIZE(shader_stages),
	    .pStages = shader_stages,
	    .pVertexInputState = &vertex_input_state,
	    .pInputAssemblyState = &input_assembly_state,
	    .pViewportState = &viewport_state,
	    .pRasterizationState = &rasterization_state,
	    .pMultisampleState = &multisample_state,
	    .pDepthStencilState = &depth_stencil_state,
	    .pColorBlendState = &color_blend_state,
	    .pDynamicState = &dynamic_state,
	    .layout = pipeline_layout,
	    .renderPass = render_pass,
	    .basePipelineHandle = VK_NULL_HANDLE,
	    .basePipelineIndex = -1,
	};

	VkPipeline pipeline = VK_NULL_HANDLE;
	ret = vk->vkCreateGraphicsPipelines(vk->device,     //
	                                    pipeline_cache, //
	                                    1,              //
	                                    &pipeline_info, //
	                                    NULL,           //
	                                    &pipeline);     //
	if (ret != VK_SUCCESS) {
		VK_DEBUG(vk, "vkCreateGraphicsPipelines failed: %s",
		         vk_result_string(ret));
		return ret;
	}

	*out_mesh_pipeline = pipeline;

	return VK_SUCCESS;
}

static bool
init_mesh_ubo_buffers(struct vk_bundle *vk,
                      struct comp_buffer *l_ubo,
                      struct comp_buffer *r_ubo)
{
	// Using the same flags for all ubos.
	VkBufferUsageFlags ubo_usage_flags = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT;
	VkMemoryPropertyFlags memory_property_flags =
	    VK_MEMORY_PROPERTY_HOST_COHERENT_BIT |
	    VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT;

	// Distortion ubo size.
	VkDeviceSize ubo_size = sizeof(struct comp_mesh_ubo_data);

	C(comp_buffer_init(vk,                    //
	                   l_ubo,                 //
	                   ubo_usage_flags,       //
	                   memory_property_flags, //
	                   ubo_size));            // size
	C(comp_buffer_map(vk, l_ubo));

	C(comp_buffer_init(vk,                    //
	                   r_ubo,                 //
	                   ubo_usage_flags,       //
	                   memory_property_flags, //
	                   ubo_size));            // size
	C(comp_buffer_map(vk, r_ubo));


	return true;
}

static void
update_mesh_discriptor_set(struct vk_bundle *vk,
                           uint32_t src_binding,
                           VkSampler sampler,
                           VkImageView image_view,
                           uint32_t ubo_binding,
                           VkBuffer buffer,
                           VkDeviceSize size,
                           VkDescriptorSet descriptor_set)
{
	VkDescriptorImageInfo image_info = {
	    .sampler = sampler,
	    .imageView = image_view,
	    .imageLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL,
	};

	VkDescriptorBufferInfo buffer_info = {
	    .buffer = buffer,
	    .offset = 0,
	    .range = size,
	};

	VkWriteDescriptorSet write_descriptor_sets[2] = {
	    {
	        .sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET,
	        .dstSet = descriptor_set,
	        .dstBinding = src_binding,
	        .descriptorCount = 1,
	        .descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER,
	        .pImageInfo = &image_info,
	    },
	    {
	        .sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET,
	        .dstSet = descriptor_set,
	        .dstBinding = ubo_binding,
	        .descriptorCount = 1,
	        .descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER,
	        .pBufferInfo = &buffer_info,
	    },
	};

	vk->vkUpdateDescriptorSets(
	    vk->device,                        //
	    ARRAY_SIZE(write_descriptor_sets), // descriptorWriteCount
	    write_descriptor_sets,             // pDescriptorWrites
	    0,                                 // descriptorCopyCount
	    NULL);                             // pDescriptorCopies
}


/*
 *
 * 'Exported' rendering functions.
 *
 */

bool
comp_rendering_init(struct comp_compositor *c,
                    struct comp_resources *r,
                    struct comp_rendering *rr)
{
	struct vk_bundle *vk = &c->vk;
	rr->c = c;
	rr->r = r;


	/*
	 * Per rendering.
	 */

	C(create_command_buffer(vk, &rr->cmd));


	/*
	 * Mesh per view
	 */

	C(create_descriptor_set(
	    vk,                                  // vk_bundle
	    r->mesh_descriptor_pool,             // descriptor_pool
	    r->mesh.descriptor_set_layout,       // descriptor_set_layout
	    &rr->views[0].mesh.descriptor_set)); // descriptor_set

	C(create_descriptor_set(
	    vk,                                  // vk_bundle
	    r->mesh_descriptor_pool,             // descriptor_pool
	    r->mesh.descriptor_set_layout,       // descriptor_set_layout
	    &rr->views[1].mesh.descriptor_set)); // descriptor_set

	if (!init_mesh_ubo_buffers(vk,                     //
	                           &rr->views[0].mesh.ubo, //
	                           &rr->views[1].mesh.ubo)) {
		return false;
	}

	return true;
}

void
comp_rendering_close(struct comp_rendering *rr)
{
	struct vk_bundle *vk = &rr->c->vk;
	struct comp_resources *r = rr->r;

	D(RenderPass, rr->render_pass);
	D(Pipeline, rr->mesh.pipeline);
	D(Framebuffer, rr->targets[0].framebuffer);
	D(Framebuffer, rr->targets[1].framebuffer);
	comp_buffer_close(vk, &rr->views[0].mesh.ubo);
	comp_buffer_close(vk, &rr->views[1].mesh.ubo);
	DD(r->mesh_descriptor_pool, rr->views[0].mesh.descriptor_set);
	DD(r->mesh_descriptor_pool, rr->views[1].mesh.descriptor_set);

	U_ZERO(rr);
}


/*
 *
 * 'Exported' draw functions.
 *
 */

bool
comp_draw_begin_target_single(struct comp_rendering *rr,
                              VkImageView target,
                              struct comp_target_data *data)
{
	struct vk_bundle *vk = &rr->c->vk;
	struct comp_resources *r = rr->r;

	rr->targets[0].data = *data;
	rr->num_targets = 1;

	assert(data->is_external);

	C(create_external_render_pass( //
	    vk,                        // vk_bundle
	    data->format,              // target_format
	    &rr->render_pass));        // out_render_pass

	C(create_mesh_pipeline(
	    vk,                        // vk_bundle
	    rr->render_pass,           // render_pass
	    r->mesh.pipeline_layout,   // pipeline_layout
	    r->pipeline_cache,         // pipeline_cache
	    r->mesh.src_binding,       // src_binding
	    r->mesh.total_num_indices, // mesh_total_num_indices
	    r->mesh.stride,            // mesh_stride
	    rr->c->shaders.mesh_vert,  // mesh_vert
	    rr->c->shaders.mesh_frag,  // mesh_frag
	    &rr->mesh.pipeline));      // out_mesh_pipeline

	C(create_framebuffer(
	    vk,                            // vk_bundle,
	    target,                        // image_view,
	    rr->render_pass,               // render_pass,
	    data->width,                   // width,
	    data->height,                  // height,
	    &rr->targets[0].framebuffer)); // out_external_framebuffer

	C(begin_command_buffer(vk, rr->cmd));

	// This is shared across both views.
	begin_render_pass(vk,                          //
	                  rr->cmd,                     //
	                  rr->render_pass,             //
	                  rr->targets[0].framebuffer,  //
	                  rr->targets[0].data.width,   //
	                  rr->targets[0].data.height); //

	return true;
}

void
comp_draw_end_target(struct comp_rendering *rr)
{
	struct vk_bundle *vk = &rr->c->vk;
	VkResult ret;

	//! We currently only support single target mode.
	assert(rr->num_targets == 1);

	// Stop the shared render pass.
	vk->vkCmdEndRenderPass(rr->cmd);

	// End the command buffer.
	ret = vk->vkEndCommandBuffer(rr->cmd);
	if (ret != VK_SUCCESS) {
		VK_ERROR(vk, "vkEndCommandBuffer failed: %s",
		         vk_result_string(ret));
		return;
	}
}

void
comp_draw_begin_view(struct comp_rendering *rr,
                     uint32_t target,
                     uint32_t view,
                     struct comp_viewport_data *viewport_data)
{
	struct vk_bundle *vk = &rr->c->vk;

	rr->current_view = view;

	//! We currently only support single target mode.
	assert(rr->num_targets == 1);
	assert(target == 0);
	assert(view == 0 || view == 1);


	/*
	 * Viewport
	 */

	VkViewport viewport = {
	    .x = viewport_data->x,
	    .y = viewport_data->y,
	    .width = viewport_data->w,
	    .height = viewport_data->h,
	    .minDepth = 0.0f,
	    .maxDepth = 1.0f,
	};

	vk->vkCmdSetViewport(rr->cmd,    // commandBuffer
	                     0,          // firstViewport
	                     1,          // viewportCount
	                     &viewport); // pViewports

	/*
	 * Scissor
	 */

	VkRect2D scissor = {
	    .offset =
	        {
	            .x = viewport_data->x,
	            .y = viewport_data->y,
	        },
	    .extent =
	        {
	            .width = viewport_data->w,
	            .height = viewport_data->h,
	        },
	};

	vk->vkCmdSetScissor(rr->cmd,   // commandBuffer
	                    0,         // firstScissor
	                    1,         // scissorCount
	                    &scissor); // pScissors
}

void
comp_draw_end_view(struct comp_rendering *rr)
{
	//! We currently only support single target mode.
	assert(rr->num_targets == 1);
}

void
comp_draw_distortion(struct comp_rendering *rr,
                     VkSampler sampler,
                     VkImageView image_view,
                     struct comp_mesh_ubo_data *data)
{
	struct vk_bundle *vk = &rr->c->vk;
	struct comp_resources *r = rr->r;

	uint32_t view = rr->current_view;
	struct comp_rendering_view *v = &rr->views[view];

	/*
	 * Descriptors and pipeline.
	 */

	comp_buffer_write(vk, &v->mesh.ubo, data,
	                  sizeof(struct comp_mesh_ubo_data));

	update_mesh_discriptor_set(  //
	    vk,                      // vk_bundle
	    r->mesh.src_binding,     // src_binding
	    sampler,                 // sampler
	    image_view,              // image_view
	    r->mesh.ubo_binding,     // ubo_binding
	    v->mesh.ubo.buffer,      // buffer
	    VK_WHOLE_SIZE,           // size
	    v->mesh.descriptor_set); // descriptor_set

	VkDescriptorSet descriptor_sets[1] = {v->mesh.descriptor_set};
	vk->vkCmdBindDescriptorSets(         //
	    rr->cmd,                         // commandBuffer
	    VK_PIPELINE_BIND_POINT_GRAPHICS, // pipelineBindPoint
	    r->mesh.pipeline_layout,         // layout
	    0,                               // firstSet
	    ARRAY_SIZE(descriptor_sets),     // descriptorSetCount
	    descriptor_sets,                 // pDescriptorSets
	    0,                               // dynamicOffsetCount
	    NULL);                           // pDynamicOffsets

	vk->vkCmdBindPipeline(               //
	    rr->cmd,                         // commandBuffer
	    VK_PIPELINE_BIND_POINT_GRAPHICS, // pipelineBindPoint
	    rr->mesh.pipeline);              // pipeline


	/*
	 * Vertex buffer.
	 */

	VkBuffer buffers[1] = {r->mesh.vbo.buffer};
	VkDeviceSize offsets[1] = {0};
	assert(ARRAY_SIZE(buffers) == ARRAY_SIZE(offsets));

	vk->vkCmdBindVertexBuffers( //
	    rr->cmd,                // commandBuffer
	    0,                      // firstBinding
	    ARRAY_SIZE(buffers),    // bindingCount
	    buffers,                // pBuffers
	    offsets);               // pOffsets


	/*
	 * Draw with indices or not?
	 */

	if (r->mesh.total_num_indices > 0) {
		vk->vkCmdBindIndexBuffer(  //
		    rr->cmd,               // commandBuffer
		    r->mesh.ibo.buffer,    // buffer
		    0,                     // offset
		    VK_INDEX_TYPE_UINT32); // indexType

		vk->vkCmdDrawIndexed(             //
		    rr->cmd,                      // commandBuffer
		    r->mesh.num_indices[view],    // indexCount
		    1,                            // instanceCount
		    r->mesh.offset_indices[view], // firstIndex
		    0,                            // vertexOffset
		    0);                           // firstInstance
	} else {
		vk->vkCmdDraw(            //
		    rr->cmd,              // commandBuffer
		    r->mesh.num_vertices, // vertexCount
		    1,                    // instanceCount
		    0,                    // firstVertex
		    0);                   // firstInstance
	}
}