render-zig

commit 04d09de0b45d9d57e623811aa525fd7ad9f0aca2
parent e8c54fdd890cb1cd5da91b2de598de228d03a766
Author: Christian Ermann <christianermann@gmail.com>
Date:   Sun,  8 Dec 2024 17:33:28 -0800

Add cube

Diffstat:
A
src/cube.zig
 | 
139
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
src/main.zig
 | 
10
++++++++++

2 files changed, 149 insertions(+), 0 deletions(-)
diff --git a/src/cube.zig b/src/cube.zig
@@ -0,0 +1,139 @@
+const std = @import("std");
+
+const Mesh = @import("mesh.zig");
+
+const f32x3 = @Vector(3, f32);
+const f32x4 = @Vector(4, f32);
+
+pub fn generateCube(n_subdivisions: u32, allocator: std.mem.Allocator) !Mesh {
+    var positions = std.ArrayList(f32x4).init(allocator);
+    var normals = std.ArrayList(f32x3).init(allocator);
+    var tex_coords = std.ArrayList(f32x3).init(allocator);
+    defer positions.deinit();
+    defer normals.deinit();
+    defer tex_coords.deinit();
+
+    try generateFace(&positions, &normals, &tex_coords, n_subdivisions, .{
+        .u_axis = 0,
+        .v_axis = 1,
+        .w_axis = 2,
+        .u_dir = 1,
+        .v_dir = 1,
+        .w_dir = 1,
+    });
+    try generateFace(&positions, &normals, &tex_coords, n_subdivisions, .{
+        .u_axis = 0,
+        .v_axis = 1,
+        .w_axis = 2,
+        .u_dir = -1,
+        .v_dir = 1,
+        .w_dir = -1,
+    });
+    try generateFace(&positions, &normals, &tex_coords, n_subdivisions, .{
+        .u_axis = 2,
+        .v_axis = 1,
+        .w_axis = 0,
+        .u_dir = -1,
+        .v_dir = 1,
+        .w_dir = 1,
+    });
+    try generateFace(&positions, &normals, &tex_coords, n_subdivisions, .{
+        .u_axis = 2,
+        .v_axis = 1,
+        .w_axis = 0,
+        .u_dir = 1,
+        .v_dir = 1,
+        .w_dir = -1,
+    });
+    try generateFace(&positions, &normals, &tex_coords, n_subdivisions, .{
+        .u_axis = 0,
+        .v_axis = 2,
+        .w_axis = 1,
+        .u_dir = 1,
+        .v_dir = 1,
+        .w_dir = -1,
+    });
+    try generateFace(&positions, &normals, &tex_coords, n_subdivisions, .{
+        .u_axis = 0,
+        .v_axis = 2,
+        .w_axis = 1,
+        .u_dir = 1,
+        .v_dir = -1,
+        .w_dir = 1,
+    });
+
+    var indices = std.ArrayList(u32).init(allocator);
+    defer indices.deinit();
+    var offset: u32 = 0;
+    for (0..6) |_| {
+        offset += try generateFaceIndices(&indices, n_subdivisions, offset);
+    }
+
+    const n_vertices: u32 = @intCast(positions.items.len);
+    var mesh = Mesh{
+        .positions = try positions.toOwnedSlice(),
+        .normals = try normals.toOwnedSlice(),
+        .tex_coords = try tex_coords.toOwnedSlice(),
+        .indices = try indices.toOwnedSlice(),
+        .tangents = try allocator.alloc(f32x3, n_vertices),
+        .bitangents = try allocator.alloc(f32x3, n_vertices),
+    };
+
+    try mesh.tangentsAndBitangents(allocator);
+    return mesh;
+}
+
+const FaceOptions = struct {
+    u_axis: u32,
+    v_axis: u32,
+    w_axis: u32,
+    u_dir: f32,
+    v_dir: f32,
+    w_dir: f32,
+};
+
+fn generateFace(
+    positions: *std.ArrayList(f32x4),
+    normals: *std.ArrayList(f32x3),
+    tex_coords: *std.ArrayList(f32x3),
+    n_subdivisions: u32,
+    face_options: FaceOptions,
+) !void {
+    for (0..n_subdivisions + 2) |i| {
+        const v = @as(f32, @floatFromInt(i)) / @as(f32, @floatFromInt(n_subdivisions + 1));
+        for (0..n_subdivisions + 2) |j| {
+            const u = @as(f32, @floatFromInt(j)) / @as(f32, @floatFromInt(n_subdivisions + 1));
+            var position = f32x4{ 0, 0, 0, 1 };
+            position[face_options.u_axis] = (u - 0.5) * face_options.u_dir;
+            position[face_options.v_axis] = (v - 0.5) * face_options.v_dir;
+            position[face_options.w_axis] = 0.5 * face_options.w_dir;
+            var normal = f32x3{ 0, 0, 0 };
+            normal[face_options.w_axis] = face_options.w_dir;
+            const tex_coord = f32x3{ u, v, 0.0 };
+
+            try positions.append(position);
+            try normals.append(normal);
+            try tex_coords.append(tex_coord);
+        }
+    }
+}
+
+fn generateFaceIndices(
+    indices: *std.ArrayList(u32),
+    n_subdivisions: u32,
+    offset: u32,
+) !u32 {
+    for (0..n_subdivisions + 1) |i| {
+        for (0..n_subdivisions + 1) |j| {
+            const a: u32 = @intCast(i * (n_subdivisions + 2) + j + offset);
+            const b: u32 = @intCast((i + 1) * (n_subdivisions + 2) + j + offset);
+            try indices.append(a);
+            try indices.append(a + 1);
+            try indices.append(b + 1);
+            try indices.append(a);
+            try indices.append(b + 1);
+            try indices.append(b);
+        }
+    }
+    return (n_subdivisions + 2) * (n_subdivisions + 2);
+}
diff --git a/src/main.zig b/src/main.zig
@@ -431,6 +431,9 @@ pub fn main() !void {
     const generateUVSphere = @import("uvsphere.zig").generateUVSphere;
     const sphere_mesh = try generateUVSphere(16, 16, allocator);
 
+    const generateCube = @import("cube.zig").generateCube;
+    const cube_mesh = try generateCube(1, allocator);
+
     var rp = try MeshRenderPipeline.init(
         &app,
         .{
@@ -462,6 +465,7 @@ pub fn main() !void {
     var transform_1 = Transform{};
     var transform_2 = Transform{};
     var transform_3 = Transform{ .offset = .{ 3, 3, 3 } };
+    var transform_4 = Transform{ .offset = .{ -3, -3, 0 } };
 
     var render_mesh = try render_data.addMesh(
         &transform_1,
@@ -481,6 +485,12 @@ pub fn main() !void {
         allocator,
     );
 
+    _ = try render_data.addMesh(
+        &transform_4,
+        &cube_mesh,
+        allocator,
+    );
+
     const corners = mesh.bboxVertices();
     const bbox_indices = Mesh.bboxIndices();