Wireframe rendering.

CMakeLists.txt

@@ -42,6 +42,7 @@ add_executable(vk_expe
 
 add_shaders(vk_expe
     shaders/shader.vert
+    shaders/shader.geom
     shaders/shader.frag
 )
 

shaders/shader.frag

@@ -1,9 +1,28 @@
 #version 450
 
-layout(location = 0) in vec3 fragColor;
+layout(location = 1) in vec3 in_normal;
+layout(location = 2) in vec3 in_color;
+layout(location = 3) in vec3 in_edge_dist;
 
-layout(location = 0) out vec4 outColor;
+layout(location = 0) out vec4 out_color;
 
 void main() {
-    outColor = vec4(fragColor, 1.0);
+    vec3 edge_dist = vec3(0.75) - in_edge_dist;
+    float edge = clamp(
+        max(edge_dist[0], max(edge_dist[1], edge_dist[2])),
+        0.0, 1.0
+    );
+
+    vec3 edge_color = vec3(1.0);
+    vec3 light_dir = normalize(vec3(-0.2, -0.1, -1.0));
+
+    vec3 color = in_color;
+
+    // vec3 normal = normalize(in_normal);
+    // color *= clamp(
+    //     dot(normal, light_dir),
+    //     0.0, 1.0
+    // );
+
+    out_color = vec4(mix(color, edge_color, edge), 1.0);
 }

shaders/shader.geom

@@ -0,0 +1,49 @@
+#version 450
+
+layout(triangles) in;
+layout(triangle_strip, max_vertices=3) out;
+
+layout(binding = 0) uniform Uniforms {
+    mat4 scene_from_model;
+    mat4 projection_from_scene;
+    vec2 half_screen_size;
+    float lod;
+} uniforms;
+
+layout(location = 0) in vec4 in_position[3];
+layout(location = 1) in vec3 in_normal[3];
+layout(location = 2) in vec3 in_color[3];
+
+layout(location = 0) out vec4 out_position;
+layout(location = 1) out vec3 out_normal;
+layout(location = 2) out vec3 out_color;
+layout(location = 3) noperspective out vec3 out_edge_dist;
+
+void main() {
+    vec2 positions[3] = {
+        uniforms.half_screen_size * gl_in[0].gl_Position.xy / gl_in[0].gl_Position.w,
+        uniforms.half_screen_size * gl_in[1].gl_Position.xy / gl_in[1].gl_Position.w,
+        uniforms.half_screen_size * gl_in[2].gl_Position.xy / gl_in[2].gl_Position.w,
+    };
+
+    for(int i = 0; i < 3; i += 1) {
+        gl_Position = gl_in[i].gl_Position;
+        out_position = in_position[i];
+        out_normal = in_normal[i];
+        out_color = in_color[i];
+        out_edge_dist = vec3(0.0);
+
+        vec2 p0 = positions[(i + 0) % 3];
+        vec2 p1 = positions[(i + 1) % 3];
+        vec2 p2 = positions[(i + 2) % 3];
+
+        // vec2 v21 = p2 - p1;
+        // out_edge_dist[i] = (p1.x * v21.x + p1.y * v21.y) / dot(v21, v21);
+
+        vec2 v0 = p0 - p2;
+        vec2 v1 = p1 - p2;
+        out_edge_dist[i] = determinant(mat2(v0, v1)) / length(v1);
+
+        EmitVertex();
+    }
+}

shaders/shader.vert

@@ -3,17 +3,31 @@
 layout(binding = 0) uniform Uniforms {
     mat4 scene_from_model;
     mat4 projection_from_scene;
+    vec2 screen_size;
+    float lod;
 } uniforms;
 
-layout(location = 0) in vec3 inPosition;
-layout(location = 1) in vec3 inColor;
+layout(location = 0) in vec3 in_position;
+layout(location = 1) in vec3 in_position2;
+layout(location = 2) in vec3 in_normal;
+layout(location = 3) in vec3 in_color;
 
-layout(location = 0) out vec3 fragColor;
+layout(location = 0) out vec4 out_position;
+layout(location = 1) out vec3 out_normal;
+layout(location = 2) out vec3 out_color;
 
 void main() {
-    gl_Position =
+    float lod = clamp(
+        2.0 * dot(transpose(uniforms.scene_from_model)[0].xyz, in_position) + 0.5,
+        0.0, 1.0
+    );
+    vec3 position = mix(in_position2, in_position, lod);
+    out_position =
         uniforms.projection_from_scene *
         uniforms.scene_from_model *
-        vec4(inPosition, 1.0);
-    fragColor = inColor;
+        vec4(position, 1.0);
+    out_normal = in_normal;
+    out_color = in_color;
+
+    gl_Position = out_position;
 }

src/Planet.cpp

@@ -38,7 +38,7 @@ size_t Cell::triangle_count(uint32_t subdiv_count) {
 }
 
 void Cell::build_mesh(
-    Vector3AV positions, TriangleAV triangles,
+    Vector3AV positions, Vector3AV positions2, Vector3AV normals, TriangleAV triangles,
     uint32_t subdiv_count, Index index_offset
 ) const {
     auto const side_edge_count = (1u << subdiv_count);
@@ -54,8 +54,8 @@ void Cell::build_mesh(
     auto const index = [side_vert_count](uint32_t x, uint32_t y) -> uint32_t {
         return x + y * side_vert_count;
     };
-    auto const vertex = [&positions, &index](uint32_t x, uint32_t y) -> Vector3& {
-        return positions[index(x, y)];
+    auto const vertex = [&normals, &index](uint32_t x, uint32_t y) -> Vector3& {
+        return normals[index(x, y)];
     };
 
     vertex(              0,               0) = m_corners[0];
@@ -106,18 +106,48 @@ void Cell::build_mesh(
         }
     }
 
+    for (Index index = 0; index < normals.size(); index += 1) {
+        positions[index] = normals[index];
+    }
+
+    int x_offset = (
+        m_corners[0][0] < m_corners[1][0] ||
+        m_corners[0][1] < m_corners[1][1] ||
+        m_corners[0][2] < m_corners[1][2]
+    )? -1: 1;
+    int y_offset = (
+        m_corners[0][0] < m_corners[2][0] ||
+        m_corners[0][1] < m_corners[2][1] ||
+        m_corners[0][2] < m_corners[2][2]
+    )? -1: 1;
+    for(Index y = 0; y < side_vert_count; y += 1) {
+        for(Index x = 0; x < side_vert_count; x += 1) {
+            Index x2 = x + (x & 0x01) * x_offset;
+            Index y2 = y + (y & 0x01) * y_offset;
+
+            positions2[index(x, y)] = positions[index(x2, y2)];
+        }
+    }
+
     auto triangleIndex = 0;
-    for(uint32_t y = 0; y < side_edge_count; y += 1) {
-        for(uint32_t x = 0; x < side_edge_count; x += 1) {
+    bool flip = false; // (x_offset > 0) ^ (y_offset > 0);
+    for(Index y = 0; y < side_edge_count; y += 1) {
+        for(Index x = 0; x < side_edge_count; x += 1) {
             const auto i00 = index_offset + index(x, y);
             const auto i01 = i00 + 1;
             const auto i10 = i00 + side_vert_count;
             const auto i11 = i10 + 1;
 
+            if (flip) {
+                triangles[triangleIndex++] = Triangle { i00, i01, i11 };
+                triangles[triangleIndex++] = Triangle { i00, i11, i10 };
+            }
+            else {
                 triangles[triangleIndex++] = Triangle { i00, i01, i10 };
                 triangles[triangleIndex++] = Triangle { i10, i01, i11 };
             }
         }
+    }
 }
 
 Real Cell::height_factor(Vector3 corners[CornerCount]) {
@@ -169,7 +199,7 @@ Planet::Planet()
 {}
 
 void Planet::build_mesh(
-    Vector3AV positions, TriangleAV triangles,
+    Vector3AV positions, Vector3AV positions2, Vector3AV normals, TriangleAV triangles,
     uint32_t subdiv_count, Index index_offset
 ) const {
     auto const vertex_count = Cell::vertex_count(subdiv_count);
@@ -179,11 +209,19 @@ void Planet::build_mesh(
         auto sub_positions = positions.slice(
             cell_index * vertex_count, vertex_count
         );
+        auto sub_positions2 = positions2.slice(
+            cell_index * vertex_count, vertex_count
+        );
+        auto sub_normals = normals.slice(
+            cell_index * vertex_count, vertex_count
+        );
         auto sub_triangles = triangles.slice(
             cell_index * index_count, index_count
         );
         cell(cell_index).build_mesh(
             sub_positions,
+            sub_positions2,
+            sub_normals,
             sub_triangles,
             subdiv_count,
             index_offset + cell_index * vertex_count

src/Planet.h

@@ -12,6 +12,8 @@ using CellUP = std::unique_ptr<Cell>;
 
 struct Vertex {
     Vector3 position;
+    Vector3 position2;
+    Vector3 normal;
     Vector3 color;
 };
 
@@ -41,7 +43,7 @@ public:
     static size_t triangle_count(uint32_t subdiv_count);
 
     void build_mesh(
-        Vector3AV positions, TriangleAV triangles,
+        Vector3AV positions, Vector3AV positions2, Vector3AV normals, TriangleAV triangles,
         uint32_t subdiv_count=4, Index index_offset=0
     ) const;
 
@@ -78,8 +80,10 @@ public:
         return m_cells[cell_index];
     }
 
-    void build_mesh(Vector3AV positions, TriangleAV triangles,
-        uint32_t subdiv_count=4, Index index_offset=0) const;
+    void build_mesh(
+        Vector3AV positions, Vector3AV positions2, Vector3AV normals, TriangleAV triangles,
+        uint32_t subdiv_count=4, Index index_offset=0
+    ) const;
 
 private:
     Cell m_cells[CellCount];

src/Vulkan/Context.cpp

@@ -737,6 +737,13 @@ std::optional<VkPhysicalDeviceProperties> Context::select_physical_device(
     VkPhysicalDeviceProperties device_properties;
     vkGetPhysicalDeviceProperties(physical_device, &device_properties);
 
+    VkPhysicalDeviceFeatures available_features;
+    vkGetPhysicalDeviceFeatures(physical_device, &available_features);
+
+    if (!available_features.geometryShader)
+        return std::nullopt;
+
+
     m_transfer_queue_index = settings.queues().size();
     m_queue_families.assign(settings.queues().size() + 1, INVALID_QUEUE_FAMILY);
     m_presentation_queue_family = INVALID_QUEUE_FAMILY;
@@ -841,6 +848,7 @@ void Context::create_device(const ContextSettings& settings) {
     }
 
     VkPhysicalDeviceFeatures const device_features {
+        .geometryShader = true,
     };
 
     std::vector<const char*> extensions;

src/VulkanTutorial.cpp

@@ -24,7 +24,7 @@ VkVertexInputBindingDescription vertex_binding_description() {
     };
 }
 
-std::array<VkVertexInputAttributeDescription, 2> vertex_attributes_description() {
+std::array<VkVertexInputAttributeDescription, 4> vertex_attributes_description() {
     return {
         VkVertexInputAttributeDescription {
             .location = 0,
@@ -32,10 +32,22 @@ std::array<VkVertexInputAttributeDescription, 2> vertex_attributes_description()
             .format = VK_FORMAT_R32G32B32_SFLOAT,
             .offset = offsetof(Vertex, position),
         },
-        {
+        VkVertexInputAttributeDescription {
             .location = 1,
             .binding = 0,
             .format = VK_FORMAT_R32G32B32_SFLOAT,
+            .offset = offsetof(Vertex, position2),
+        },
+        VkVertexInputAttributeDescription {
+            .location = 2,
+            .binding = 0,
+            .format = VK_FORMAT_R32G32B32_SFLOAT,
+            .offset = offsetof(Vertex, normal),
+        },
+        {
+            .location = 3,
+            .binding = 0,
+            .format = VK_FORMAT_R32G32B32_SFLOAT,
             .offset = offsetof(Vertex, color),
         },
     };
@@ -43,40 +55,42 @@ std::array<VkVertexInputAttributeDescription, 2> vertex_attributes_description()
 
 
 std::vector<Vertex> vertices = {
-    {{-0.5f, -0.5f, -0.5f}, {1.0f, 0.0f, 0.0f}},
-    {{0.5f, -0.5f, -0.5f}, {0.0f, 1.0f, 0.0f}},
-    {{-0.5f, 0.5f, -0.5f}, {0.0f, 0.0f, 1.0f}},
-    {{0.5f, 0.5f, -0.5f}, {1.0f, 1.0f, 1.0f}},
-
-    {{-0.5f, -0.5f, 0.5f}, {0.0f, 1.0f, 1.0f}},
-    {{0.5f, -0.5f, 0.5f}, {1.0f, 0.0f, 1.0f}},
-    {{-0.5f, 0.5f, 0.5f}, {1.0f, 1.0f, 0.0f}},
-    {{0.5f, 0.5f, 0.5f}, {0.2f, 0.2f, 0.2f}},
+    // {{-0.5f, -0.5f, -0.5f}, {1.0f, 0.0f, 0.0f}},
+    // {{0.5f, -0.5f, -0.5f}, {0.0f, 1.0f, 0.0f}},
+    // {{-0.5f, 0.5f, -0.5f}, {0.0f, 0.0f, 1.0f}},
+    // {{0.5f, 0.5f, -0.5f}, {1.0f, 1.0f, 1.0f}},
+
+    // {{-0.5f, -0.5f, 0.5f}, {0.0f, 1.0f, 1.0f}},
+    // {{0.5f, -0.5f, 0.5f}, {1.0f, 0.0f, 1.0f}},
+    // {{-0.5f, 0.5f, 0.5f}, {1.0f, 1.0f, 0.0f}},
+    // {{0.5f, 0.5f, 0.5f}, {0.2f, 0.2f, 0.2f}},
 };
 
 std::vector<uint32_t> indices = {
-    0, 1, 2,
-    2, 1, 3,
+    // 0, 1, 2,
+    // 2, 1, 3,
 
-    1, 5, 3,
-    3, 5, 7,
+    // 1, 5, 3,
+    // 3, 5, 7,
 
-    5, 4, 7,
-    7, 4, 6,
+    // 5, 4, 7,
+    // 7, 4, 6,
 
-    4, 0, 6,
-    6, 0, 2,
+    // 4, 0, 6,
+    // 6, 0, 2,
 
-    0, 4, 1,
-    1, 4, 5,
+    // 0, 4, 1,
+    // 1, 4, 5,
 
-    2, 3, 6,
-    6, 3, 7,
+    // 2, 3, 6,
+    // 6, 3, 7,
 };
 
 struct Uniforms {
     alignas(16) Eigen::Matrix4f scene_from_model;
     alignas(16) Eigen::Matrix4f projection_from_scene;
+    alignas(8) Eigen::Vector2f half_screen_size;
+    alignas(4) float lod;
 };
 
 
@@ -91,24 +105,21 @@ VulkanTutorial::VulkanTutorial() {
     vertices.resize(6 * Cell::vertex_count(subdiv_count));
     indices.resize(6 * 3 * Cell::triangle_count(subdiv_count));
 
-    // MeshView mesh(
-    //     vertices.size(),
-    //     reinterpret_cast<Byte*>(vertices.data()) + offsetof(Vertex, position),
-    //     sizeof(Vertex),
-    //     nullptr,
-    //     sizeof(Vertex),
-    //     reinterpret_cast<Byte*>(vertices.data()) + offsetof(Vertex, color),
-    //     sizeof(Vertex),
-    //     indices.size(),
-    //     reinterpret_cast<Byte*>(indices.data()),
-    //     sizeof(Index)
-    // );
-
     Vector3AV positions(
         vertices.size(), vertices.data(),
         sizeof(Vertex), offsetof(Vertex, position)
     );
 
+    Vector3AV positions2(
+        vertices.size(), vertices.data(),
+        sizeof(Vertex), offsetof(Vertex, position2)
+    );
+
+    Vector3AV normals(
+        vertices.size(), vertices.data(),
+        sizeof(Vertex), offsetof(Vertex, normal)
+    );
+
     Vector3AV colors(
         vertices.size(), vertices.data(),
         sizeof(Vertex), offsetof(Vertex, color)
@@ -120,7 +131,7 @@ VulkanTutorial::VulkanTutorial() {
     );
 
     Planet planet;
-    planet.build_mesh(positions, triangles, subdiv_count);
+    planet.build_mesh(positions, positions2, normals, triangles, subdiv_count);
 
     for (size_t vertex_index = 0; vertex_index < vertices.size(); vertex_index += 1) {
         colors[vertex_index] =
@@ -195,7 +206,7 @@ void VulkanTutorial::draw_frame() {
     }
     m_last_frame_time = now;
 
-    const float alpha = SecondsD(m_time).count() * (2.0 * M_PI) / 3.0;
+    const float alpha = SecondsD(m_time).count() * (2.0 * M_PI) / 10.0;
     const float dist = 2.0f;
     const Eigen::Matrix4f view = look_at_matrix(
         // Eigen::Vector3f(0.0f, 0.0f, -dist),
@@ -226,6 +237,11 @@ void VulkanTutorial::draw_frame() {
     const Uniforms uniforms = {
         .scene_from_model = model.matrix(),
         .projection_from_scene = proj * view,
+        .half_screen_size = {
+            0.5 * m_swapchain.extent().width,
+            0.5 * m_swapchain.extent().height,
+        },
+        .lod = std::cos(alpha) * 0.5f + 0.5f,
     };
 
     void* uniform_buffer;
@@ -381,7 +397,7 @@ void VulkanTutorial::create_descriptor_set_layout() {
         .binding = 0,
         .descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER,
         .descriptorCount = 1,
-        .stageFlags = VK_SHADER_STAGE_VERTEX_BIT,
+        .stageFlags = VK_SHADER_STAGE_VERTEX_BIT | VK_SHADER_STAGE_GEOMETRY_BIT,
     };
 
     VkDescriptorSetLayoutCreateInfo layout_info {
@@ -405,6 +421,12 @@ void VulkanTutorial::create_graphic_pipeline() {
         vkDestroyShaderModule(m_context.device(), vertex_shader_module, nullptr);
     });
 
+    auto const geometry_shader_module =
+        m_context.create_shader_module_from_file("shaders/shader.geom.spv");
+    auto const geometry_shader_guard = make_guard([&]{
+        vkDestroyShaderModule(m_context.device(), geometry_shader_module, nullptr);
+    });
+
     auto const fragment_shader_module =
         m_context.create_shader_module_from_file("shaders/shader.frag.spv");
     auto const fragment_shader_guard = make_guard([&]{
@@ -418,6 +440,12 @@ void VulkanTutorial::create_graphic_pipeline() {
             .module = vertex_shader_module,
             .pName = "main",
         },
+        {
+            .sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO,
+            .stage = VK_SHADER_STAGE_GEOMETRY_BIT,
+            .module = geometry_shader_module,
+            .pName = "main",
+        },
         {
             .sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO,
             .stage = VK_SHADER_STAGE_FRAGMENT_BIT,
@@ -534,7 +562,7 @@ void VulkanTutorial::create_graphic_pipeline() {
 
     VkGraphicsPipelineCreateInfo pipeline_info {
         .sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO,
-        .stageCount = 2,
+        .stageCount = 3,
         .pStages = shader_stage_infos,
         .pVertexInputState = &vertex_info,
         .pInputAssemblyState = &assembly_info,
@@ -819,6 +847,13 @@ void VulkanTutorial::create_command_buffers() {
             offsets
         );
 
+        vkCmdBindIndexBuffer(
+            command_buffer,
+            m_index_buffer,
+            0,
+            VK_INDEX_TYPE_UINT32
+        );
+
         vkCmdBindDescriptorSets(
             command_buffer,
             VK_PIPELINE_BIND_POINT_GRAPHICS,
@@ -827,13 +862,6 @@ void VulkanTutorial::create_command_buffers() {
             0, nullptr
         );
 
-        vkCmdBindIndexBuffer(
-            command_buffer,
-            m_index_buffer,
-            0,
-            VK_INDEX_TYPE_UINT32
-        );
-
         vkCmdDrawIndexed(
             command_buffer,
             uint32_t(indices.size()),

src/VulkanTutorial.h

@@ -11,7 +11,7 @@
 
 
 VkVertexInputBindingDescription vertex_binding_description();
-std::array<VkVertexInputAttributeDescription, 2> vertex_attributes_description();
+std::array<VkVertexInputAttributeDescription, 4> vertex_attributes_description();
 
 
 class VulkanTutorial {