diff --git a/src/main.zig b/src/main.zig index 48c419b..336e8cf 100644 --- a/src/main.zig +++ b/src/main.zig @@ -2,36 +2,7 @@ const std = @import("std"); const GeneralPurposeAllocator = std.heap.GeneralPurposeAllocator(.{}); const core = @import("mach-core"); -const gpu = core.gpu; - -const zm = @import("zmath"); -const vec = zm.f32x4; -const Mat = zm.Mat; - -const primitives = @import("./primitives.zig"); -const VertexData = primitives.VertexData; -const PrimitiveData = primitives.PrimitiveData; - -/// Holds information about how a perticular scene should be rendered. -const SceneUniformBuffer = struct { - view_proj_matrix: zm.Mat, -}; - -/// Holds information about where and how an object should be rendered. -const ObjectUniformBuffer = struct { - model_matrix: zm.Mat, - color: [3]f32, -}; - -/// Holds data on what is needed to render an object in a rendering pass. -const ObjectData = struct { - /// Reference to data stored on the GPU of type `ObjectUniformBuffer`. - uniform_buffer: *gpu.Buffer, - /// Bind group used to associate the buffer to the `object` shader parameter. - uniform_bind_group: *gpu.BindGroup, - /// Reference to the primitive (shape or model) to render for this object. - primitive: *PrimitiveData, -}; +const Renderer = @import("./renderer.zig"); pub const App = @This(); @@ -39,17 +10,11 @@ gpa: GeneralPurposeAllocator, allocator: std.mem.Allocator, random: std.rand.Random, +renderer: *Renderer, + app_timer: core.Timer, title_timer: core.Timer, -depth_texture: *gpu.Texture, -depth_texture_view: *gpu.TextureView, -pipeline: *gpu.RenderPipeline, -scene_uniform_buffer: *gpu.Buffer, -scene_uniform_bind_group: *gpu.BindGroup, -primitive_data: []PrimitiveData, -object_data: []ObjectData, - pub fn init(app: *App) !void { try core.init(.{}); @@ -68,170 +33,10 @@ pub fn init(app: *App) !void { var prng = std.rand.DefaultPrng.init(0); app.random = prng.random(); + app.renderer = try Renderer.init(app); + app.app_timer = try core.Timer.start(); app.title_timer = try core.Timer.start(); - - // Create a depth texture. This is used to ensure that when things are - // rendered, an object behind another won't draw over one in front, simply - // because it was rendered at a later point in time. - app.depth_texture = core.device.createTexture(&.{ - .usage = .{ .render_attachment = true }, - .size = .{ .width = core.descriptor.width, .height = core.descriptor.height }, - .format = .depth24_plus, - }); - app.depth_texture_view = app.depth_texture.createView(null); - - const shader_module = core.device.createShaderModuleWGSL("shader.wgsl", @embedFile("shader.wgsl")); - defer shader_module.release(); - - // Set up rendering pipeline. - app.pipeline = core.device.createRenderPipeline(&.{ - .vertex = gpu.VertexState.init(.{ - .module = shader_module, - .entry_point = "vertex_main", - .buffers = &.{ - gpu.VertexBufferLayout.init(.{ - .array_stride = @sizeOf(VertexData), - .step_mode = .vertex, - .attributes = &.{ - .{ .format = .float32x3, .shader_location = 0, .offset = @offsetOf(VertexData, "position") }, - }, - }), - }, - }), - .primitive = .{ - .topology = .triangle_list, - .front_face = .ccw, - .cull_mode = .back, - }, - .depth_stencil = &.{ - .format = .depth24_plus, - .depth_write_enabled = .true, - .depth_compare = .less, - }, - .fragment = &gpu.FragmentState.init(.{ - .module = shader_module, - .entry_point = "frag_main", - .targets = &.{.{ .format = core.descriptor.format }}, - }), - }); - - // Set up scene related uniform buffers and bind groups. - { - const result = createAndWriteUniformBuffer( - app.pipeline.getBindGroupLayout(0), - SceneUniformBuffer{ .view_proj_matrix = zm.identity() }, - ); - - app.scene_uniform_buffer = result.buffer; - app.scene_uniform_bind_group = result.bind_group; - } - - // Set up the primitives we want to render. - // Using `dupe` to allocate a slice here allows easily adjusting the - // primitives to use, without changing the type of `primitive_data`. - app.primitive_data = try app.allocator.dupe(PrimitiveData, &.{ - // primitives.createTrianglePrimitive(1.0), - // primitives.createSquarePrimitive(0.8), - // primitives.createCirclePrimitive(0.5, 24), - primitives.createCubePrimitive(0.65), - primitives.createPyramidPrimitive(0.75), - }); - - // Set up object related uniform buffers and bind groups. - // This uploads data to the GPU about all the object we - // want to render, such as their location and color. - { - const grid_size = 8; - - // Allocate a slice to store as many ObjectData as we want to create. - // - // Using a slice instead of an array means that we could change how - // many object we want to render at compile time, however it requires - // allocating, and later freeing, memory to store the slice. - app.object_data = try app.allocator.alloc(ObjectData, grid_size * grid_size); - - // Note that for loops in Zig are a little different than you might - // know from other languages. They only look over arrays, slices, - // tuples and ranges, potentially multiple at once. - for (app.object_data, 0..) |*object, i| { - const grid_max: f32 = @floatFromInt(grid_size - 1); - const x = @as(f32, @floatFromInt(i % grid_size)) / grid_max; - const z = @as(f32, @floatFromInt(i / grid_size)) / grid_max; - - const rotation = zm.rotationY(std.math.tau * (x + z) / 2.0); - const translation = zm.translation((x - 0.5) * grid_size, 0, (z - 0.5) * grid_size); - const model_matrix = zm.mul(rotation, translation); - - // Make the object have a color depending on its location in the grid. - // These values are layed out so each corner is red, green, blue and black. - const color = .{ - std.math.clamp(1.0 - x - z, 0.0, 1.0), - std.math.clamp(x - z, 0.0, 1.0), - std.math.clamp(z - x, 0.0, 1.0), - }; - - const result = createAndWriteUniformBuffer( - app.pipeline.getBindGroupLayout(1), - ObjectUniformBuffer{ - .model_matrix = zm.transpose(model_matrix), - .color = color, - }, - ); - - // Pick a "random" primitive to use for this object. - const primitive_index = app.random.int(usize) % app.primitive_data.len; - const primitive = &app.primitive_data[primitive_index]; - - // The `*object` syntax gets us a pointer to each element in the - // `object_data` slice, allowing us to override it within the loop. - object.* = .{ - .uniform_buffer = result.buffer, - .uniform_bind_group = result.bind_group, - .primitive = primitive, - }; - } - } -} - -/// Creates a buffer on the GPU to store uniform parameter information as -/// well as a bind group with the specified layout pointing to that buffer. -/// Additionally, immediately fills the buffer with the provided data. -pub fn createAndWriteUniformBuffer( - layout: *gpu.BindGroupLayout, - data: anytype, -) struct { - buffer: *gpu.Buffer, - bind_group: *gpu.BindGroup, -} { - const T = @TypeOf(data); - const usage = gpu.Buffer.UsageFlags{ .copy_dst = true, .uniform = true }; - const buffer = createAndWriteBuffer(T, &.{data}, usage); - - // "Bind groups" are used to associate data from buffers with shader parameters. - // So for example the `scene_uniform_bind_group` is accessible via `scene` in our shader. - // Essentially, buffer = data, and bind group = binding parameter to that data. - const bind_group_entry = gpu.BindGroup.Entry.buffer(0, buffer, 0, @sizeOf(T)); - const bind_group_desc = gpu.BindGroup.Descriptor.init(.{ .layout = layout, .entries = &.{bind_group_entry} }); - const bind_group = core.device.createBindGroup(&bind_group_desc); - - return .{ .buffer = buffer, .bind_group = bind_group }; -} - -/// Creates a buffer on the GPU with the specified usage -/// flags and immediately fills it with the provided data. -pub fn createAndWriteBuffer( - comptime T: type, - data: []const T, - usage: gpu.Buffer.UsageFlags, -) *gpu.Buffer { - const buffer = core.device.createBuffer(&.{ - .size = data.len * @sizeOf(T), - .usage = usage, - .mapped_at_creation = .false, - }); - core.queue.writeBuffer(buffer, 0, data); - return buffer; } pub fn deinit(app: *App) void { @@ -239,113 +44,22 @@ pub fn deinit(app: *App) void { // in the order they were created in `init`. defer core.deinit(); defer _ = app.gpa.deinit(); // TODO: Check for memory leaks? - defer app.depth_texture.release(); - defer app.depth_texture_view.release(); - defer app.pipeline.release(); - defer app.scene_uniform_buffer.release(); - defer app.scene_uniform_bind_group.release(); - defer app.allocator.free(app.primitive_data); - defer for (app.primitive_data) |p| { - p.vertex_buffer.release(); - p.index_buffer.release(); - }; - defer app.allocator.free(app.object_data); - defer for (app.object_data) |o| { - o.uniform_buffer.release(); - o.uniform_bind_group.release(); - }; + defer app.renderer.deinit(); } pub fn update(app: *App) !bool { + // Read events from the OS such as input. var iter = core.pollEvents(); while (iter.next()) |event| { switch (event) { + // Close the window when requested, such as when + // pressing the X button in the window title bar. .close => return true, else => {}, } } - // Set up a view matrix from the camera transform. - // This moves everything to be relative to the camera. - // TODO: Actually implement camera transform instead of hardcoding a look-at matrix. - // const view_matrix = zm.inverse(app.camera_transform); - const time = app.app_timer.read(); - const camera_distance = 8.0; - const x = @cos(time * std.math.tau / 20) * camera_distance; - const z = @sin(time * std.math.tau / 20) * camera_distance; - const camera_pos = vec(x, 2.0, z, 1.0); - const view_matrix = zm.lookAtLh(camera_pos, vec(0, 0, 0, 1), vec(0, 1, 0, 1)); - - // Set up a projection matrix using the size of the window. - // The perspective projection will make things further away appear smaller. - const width: f32 = @floatFromInt(core.descriptor.width); - const height: f32 = @floatFromInt(core.descriptor.height); - const field_of_view = std.math.degreesToRadians(f32, 45.0); - const proj_matrix = zm.perspectiveFovLh(field_of_view, width / height, 0.05, 80.0); - - const view_proj_matrix = zm.mul(view_matrix, proj_matrix); - - // Get back buffer texture to render to. - const back_buffer_view = core.swap_chain.getCurrentTextureView().?; - defer back_buffer_view.release(); - // Once rendering is done (hence `defer`), swap back buffer to the front to display. - defer core.swap_chain.present(); - - const render_pass_info = gpu.RenderPassDescriptor.init(.{ - .color_attachments = &.{.{ - .view = back_buffer_view, - .clear_value = std.mem.zeroes(gpu.Color), - .load_op = .clear, - .store_op = .store, - }}, - .depth_stencil_attachment = &.{ - .view = app.depth_texture_view, - .depth_load_op = .clear, - .depth_store_op = .store, - .depth_clear_value = 1.0, - }, - }); - - // Create a `WGPUCommandEncoder` which provides an interface for recording GPU commands. - const encoder = core.device.createCommandEncoder(null); - defer encoder.release(); - - // Write to the scene uniform buffer for this set of commands. - encoder.writeBuffer(app.scene_uniform_buffer, 0, &[_]SceneUniformBuffer{.{ - // All matrices the GPU has to work with need to be transposed, - // because WebGPU uses column-major matrices while zmath is row-major. - .view_proj_matrix = zm.transpose(view_proj_matrix), - }}); - - { - const pass = encoder.beginRenderPass(&render_pass_info); - defer pass.release(); - defer pass.end(); - - pass.setPipeline(app.pipeline); - pass.setBindGroup(0, app.scene_uniform_bind_group, &.{}); - - for (app.object_data) |object| { - // Set the vertex and index buffer used to render this object - // to the primitive it wants to use (either triangle or square). - const prim = object.primitive; - pass.setVertexBuffer(0, prim.vertex_buffer, 0, prim.vertex_count * @sizeOf(VertexData)); - pass.setIndexBuffer(prim.index_buffer, .uint32, 0, prim.index_count * @sizeOf(u32)); - - // Set the bind group for an object we want to render. - pass.setBindGroup(1, object.uniform_bind_group, &.{}); - - // Draw a number of triangles as specified in the index buffer. - pass.drawIndexed(prim.index_count, 1, 0, 0, 0); - } - } - - // Finish recording commands, creating a `WGPUCommandBuffer`. - var command = encoder.finish(null); - defer command.release(); - - // Submit the command(s) to the GPU. - core.queue.submit(&.{command}); + app.renderer.update(); // Update the window title to show FPS and input frequency. if (app.title_timer.read() >= 1.0) { diff --git a/src/primitives.zig b/src/primitives.zig index d17e434..2f7e065 100644 --- a/src/primitives.zig +++ b/src/primitives.zig @@ -1,10 +1,11 @@ const std = @import("std"); +const tau = std.math.tau; const core = @import("mach-core"); const gpu = core.gpu; -const main = @import("./main.zig"); -const createAndWriteBuffer = main.createAndWriteBuffer; +const Renderer = @import("./renderer.zig"); +const createAndWriteBuffer = Renderer.createAndWriteBuffer; /// Describes the layout of each vertex that a primitive is made of. pub const VertexData = struct { @@ -49,8 +50,8 @@ fn vert(x: f32, y: f32, z: f32) VertexData { pub fn createTrianglePrimitive(length: f32) PrimitiveData { const radius = length / @sqrt(3.0); const a0 = 0.0; - const a1 = std.math.tau / 3.0; - const a2 = std.math.tau / 3.0 * 2.0; + const a1 = tau / 3.0; + const a2 = tau / 3.0 * 2.0; return createPrimitive( // A triangle is made up of 3 vertices. // @@ -106,7 +107,7 @@ pub fn createCirclePrimitive(radius: f32, comptime sides: usize) PrimitiveData { var vertices: [sides]VertexData = undefined; for (&vertices, 0..) |*vertex, i| { - const angle = std.math.tau / @as(f32, @floatFromInt(sides)) * @as(f32, @floatFromInt(i)); + const angle = tau / @as(f32, @floatFromInt(sides)) * @as(f32, @floatFromInt(i)); vertex.* = vert(@sin(angle) * radius, @cos(angle) * radius, 0.0); } diff --git a/src/renderer.zig b/src/renderer.zig new file mode 100644 index 0000000..6da40d9 --- /dev/null +++ b/src/renderer.zig @@ -0,0 +1,326 @@ +const std = @import("std"); + +const core = @import("mach-core"); +const gpu = core.gpu; + +const zm = @import("zmath"); +const vec = zm.f32x4; +const Mat = zm.Mat; + +const App = @import("./main.zig"); + +const primitives = @import("./primitives.zig"); +const VertexData = primitives.VertexData; +const PrimitiveData = primitives.PrimitiveData; + +/// Holds information about how a perticular scene should be rendered. +const SceneUniformBuffer = struct { + view_proj_matrix: Mat, +}; + +/// Holds information about where and how an object should be rendered. +const ObjectUniformBuffer = struct { + model_matrix: Mat, + color: [3]f32, +}; + +/// Holds data needed to render an object in a rendering pass. +const ObjectData = struct { + /// Reference to data stored on the GPU of type `ObjectUniformBuffer`. + uniform_buffer: *gpu.Buffer, + /// Bind group used to associate the buffer to the `object` shader parameter. + uniform_bind_group: *gpu.BindGroup, + /// Reference to the primitive (shape or model) to render for this object. + primitive: *PrimitiveData, +}; + +const Renderer = @This(); + +app: *App, + +depth_texture: *gpu.Texture, +depth_texture_view: *gpu.TextureView, +pipeline: *gpu.RenderPipeline, +scene_uniform_buffer: *gpu.Buffer, +scene_uniform_bind_group: *gpu.BindGroup, + +primitive_data: []PrimitiveData, +object_data: []ObjectData, + +pub fn init(app: *App) !*Renderer { + // Create a depth texture. This is used to ensure that when things are + // rendered, an object behind another won't draw over one in front, simply + // because it was rendered at a later point in time. + const depth_texture = core.device.createTexture(&.{ + .usage = .{ .render_attachment = true }, + .size = .{ .width = core.descriptor.width, .height = core.descriptor.height }, + .format = .depth24_plus, + }); + const depth_texture_view = depth_texture.createView(null); + + const shader_module = core.device.createShaderModuleWGSL("shader.wgsl", @embedFile("shader.wgsl")); + defer shader_module.release(); + + // Set up rendering pipeline. + const pipeline = core.device.createRenderPipeline(&.{ + .vertex = gpu.VertexState.init(.{ + .module = shader_module, + .entry_point = "vertex_main", + .buffers = &.{ + gpu.VertexBufferLayout.init(.{ + .array_stride = @sizeOf(VertexData), + .step_mode = .vertex, + .attributes = &.{ + .{ .format = .float32x3, .shader_location = 0, .offset = @offsetOf(VertexData, "position") }, + }, + }), + }, + }), + .primitive = .{ + .topology = .triangle_list, + .front_face = .ccw, + .cull_mode = .back, + }, + .depth_stencil = &.{ + .format = .depth24_plus, + .depth_write_enabled = .true, + .depth_compare = .less, + }, + .fragment = &gpu.FragmentState.init(.{ + .module = shader_module, + .entry_point = "frag_main", + .targets = &.{.{ .format = core.descriptor.format }}, + }), + }); + + // Set up scene related uniform buffers and bind groups. + const scene_uniform = createAndWriteUniformBuffer( + pipeline.getBindGroupLayout(0), + SceneUniformBuffer{ .view_proj_matrix = zm.identity() }, + ); + + // Set up the primitives we want to render. + // + // Using `dupe` to allocate a slice here allows easily adjusting the + // primitives to use, without changing the type of `primitive_data`. + const primitive_data = try app.allocator.dupe(PrimitiveData, &.{ + // primitives.createTrianglePrimitive(1.0), + // primitives.createSquarePrimitive(0.8), + // primitives.createCirclePrimitive(0.5, 24), + primitives.createCubePrimitive(0.65), + primitives.createPyramidPrimitive(0.75), + }); + + // Set up object related uniform buffers and bind groups. + // This uploads data to the GPU about all the object we + // want to render, such as their location and color. + const grid_size = 8; + + // Allocate a slice to store as many ObjectData as we want to create. + // + // Using a slice instead of an array means that we could change how + // many object we want to render at compile time, however it requires + // allocating, and later freeing, memory to store the slice. + const object_data = try app.allocator.alloc(ObjectData, grid_size * grid_size); + + // Note that for loops in Zig are a little different than you might + // know from other languages. They only look over arrays, slices, + // tuples and ranges, potentially multiple at once. + for (object_data, 0..) |*object, i| { + const grid_max: f32 = @floatFromInt(grid_size - 1); + const x = @as(f32, @floatFromInt(i % grid_size)) / grid_max; + const z = @as(f32, @floatFromInt(i / grid_size)) / grid_max; + + const rotation = zm.rotationY(std.math.tau * (x + z) / 2.0); + const translation = zm.translation((x - 0.5) * grid_size, 0, (z - 0.5) * grid_size); + const model_matrix = zm.mul(rotation, translation); + + // Make the object have a color depending on its location in the grid. + // These values are layed out so each corner is red, green, blue and black. + const color = .{ + std.math.clamp(1.0 - x - z, 0.0, 1.0), + std.math.clamp(x - z, 0.0, 1.0), + std.math.clamp(z - x, 0.0, 1.0), + }; + + const object_uniform = createAndWriteUniformBuffer( + pipeline.getBindGroupLayout(1), + ObjectUniformBuffer{ + .model_matrix = zm.transpose(model_matrix), + .color = color, + }, + ); + + // Pick a "random" primitive to use for this object. + const primitive_index = app.random.int(usize) % primitive_data.len; + const primitive = &primitive_data[primitive_index]; + + // The `*object` syntax gets us a pointer to each element in the + // `object_data` slice, allowing us to override it within the loop. + object.* = .{ + .uniform_buffer = object_uniform.buffer, + .uniform_bind_group = object_uniform.bind_group, + .primitive = primitive, + }; + } + + const result = try app.allocator.create(Renderer); + result.* = .{ + .app = app, + .depth_texture = depth_texture, + .depth_texture_view = depth_texture_view, + .pipeline = pipeline, + .scene_uniform_buffer = scene_uniform.buffer, + .scene_uniform_bind_group = scene_uniform.bind_group, + .primitive_data = primitive_data, + .object_data = object_data, + }; + return result; +} + +pub fn deinit(self: *Renderer) void { + // Using `defer` here, so we can specify them + // in the order they were created in `init`. + defer self.app.allocator.destroy(self); + + defer self.depth_texture.release(); + defer self.depth_texture_view.release(); + defer self.pipeline.release(); + defer self.scene_uniform_buffer.release(); + defer self.scene_uniform_bind_group.release(); + + defer self.app.allocator.free(self.primitive_data); + defer for (self.primitive_data) |p| { + p.vertex_buffer.release(); + p.index_buffer.release(); + }; + defer self.app.allocator.free(self.object_data); + defer for (self.object_data) |o| { + o.uniform_buffer.release(); + o.uniform_bind_group.release(); + }; +} + +pub fn update(self: *Renderer) void { + // Set up a view matrix from the camera transform. + // This moves everything to be relative to the camera. + // TODO: Actually implement camera transform instead of hardcoding a look-at matrix. + // const view_matrix = zm.inverse(app.camera_transform); + const time = self.app.app_timer.read(); + const camera_distance = 8.0; + const x = @cos(time * std.math.tau / 20) * camera_distance; + const z = @sin(time * std.math.tau / 20) * camera_distance; + const camera_pos = vec(x, 2.0, z, 1.0); + const view_matrix = zm.lookAtLh(camera_pos, vec(0, 0, 0, 1), vec(0, 1, 0, 1)); + + // Set up a projection matrix using the size of the window. + // The perspective projection will make things further away appear smaller. + const width: f32 = @floatFromInt(core.descriptor.width); + const height: f32 = @floatFromInt(core.descriptor.height); + const field_of_view = std.math.degreesToRadians(f32, 45.0); + const proj_matrix = zm.perspectiveFovLh(field_of_view, width / height, 0.05, 80.0); + + const view_proj_matrix = zm.mul(view_matrix, proj_matrix); + + // Get back buffer texture to render to. + const back_buffer_view = core.swap_chain.getCurrentTextureView().?; + defer back_buffer_view.release(); + // Once rendering is done (hence `defer`), swap back buffer to the front to display. + defer core.swap_chain.present(); + + const render_pass_info = gpu.RenderPassDescriptor.init(.{ + .color_attachments = &.{.{ + .view = back_buffer_view, + .clear_value = std.mem.zeroes(gpu.Color), + .load_op = .clear, + .store_op = .store, + }}, + .depth_stencil_attachment = &.{ + .view = self.depth_texture_view, + .depth_load_op = .clear, + .depth_store_op = .store, + .depth_clear_value = 1.0, + }, + }); + + // Create a `WGPUCommandEncoder` which provides an interface for recording GPU commands. + const encoder = core.device.createCommandEncoder(null); + defer encoder.release(); + + // Write to the scene uniform buffer for this set of commands. + encoder.writeBuffer(self.scene_uniform_buffer, 0, &[_]SceneUniformBuffer{.{ + // All matrices the GPU has to work with need to be transposed, + // because WebGPU uses column-major matrices while zmath is row-major. + .view_proj_matrix = zm.transpose(view_proj_matrix), + }}); + + { + const pass = encoder.beginRenderPass(&render_pass_info); + defer pass.release(); + defer pass.end(); + + pass.setPipeline(self.pipeline); + pass.setBindGroup(0, self.scene_uniform_bind_group, &.{}); + + for (self.object_data) |object| { + // Set the vertex and index buffer used to render this object + // to the primitive it wants to use (either triangle or square). + const prim = object.primitive; + pass.setVertexBuffer(0, prim.vertex_buffer, 0, prim.vertex_count * @sizeOf(VertexData)); + pass.setIndexBuffer(prim.index_buffer, .uint32, 0, prim.index_count * @sizeOf(u32)); + + // Set the bind group for an object we want to render. + pass.setBindGroup(1, object.uniform_bind_group, &.{}); + + // Draw a number of triangles as specified in the index buffer. + pass.drawIndexed(prim.index_count, 1, 0, 0, 0); + } + } + + // Finish recording commands, creating a `WGPUCommandBuffer`. + var command = encoder.finish(null); + defer command.release(); + + // Submit the command(s) to the GPU. + core.queue.submit(&.{command}); +} + +/// Creates a buffer on the GPU to store uniform parameter information as +/// well as a bind group with the specified layout pointing to that buffer. +/// Additionally, immediately fills the buffer with the provided data. +pub fn createAndWriteUniformBuffer( + layout: *gpu.BindGroupLayout, + data: anytype, +) struct { + buffer: *gpu.Buffer, + bind_group: *gpu.BindGroup, +} { + const T = @TypeOf(data); + const usage = gpu.Buffer.UsageFlags{ .copy_dst = true, .uniform = true }; + const buffer = createAndWriteBuffer(T, &.{data}, usage); + + // "Bind groups" are used to associate data from buffers with shader parameters. + // So for example the `scene_uniform_bind_group` is accessible via `scene` in our shader. + // Essentially, buffer = data, and bind group = binding parameter to that data. + const bind_group_entry = gpu.BindGroup.Entry.buffer(0, buffer, 0, @sizeOf(T)); + const bind_group_desc = gpu.BindGroup.Descriptor.init(.{ .layout = layout, .entries = &.{bind_group_entry} }); + const bind_group = core.device.createBindGroup(&bind_group_desc); + + return .{ .buffer = buffer, .bind_group = bind_group }; +} + +/// Creates a buffer on the GPU with the specified usage +/// flags and immediately fills it with the provided data. +pub fn createAndWriteBuffer( + comptime T: type, + data: []const T, + usage: gpu.Buffer.UsageFlags, +) *gpu.Buffer { + const buffer = core.device.createBuffer(&.{ + .size = data.len * @sizeOf(T), + .usage = usage, + .mapped_at_creation = .false, + }); + core.queue.writeBuffer(buffer, 0, data); + return buffer; +}