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zig-bloxel-game
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Allow rendering of different primitives

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main
copygirl 9 months ago
parent 31efee9bdd
commit 0776a95a1a
1 changed files with 122 additions and 27 deletions
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  1. 143
      src/main.zig

143
src/main.zig
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@ -6,11 +6,6 @@ const zm = @import("zmath");
const vec = zm.f32x4;
const Mat = zm.Mat;
/// Describes the layout of each vertex that a primitive is made of.
const VertexData = struct {
position: [3]f32,
};
/// Holds information about how a perticular scene should be rendered.
const SceneUniformBuffer = struct {
view_proj_matrix: zm.Mat,
@ -22,18 +17,43 @@ const ObjectUniformBuffer = struct {
color: [3]f32,
};
/// Describes the layout of each vertex that a primitive is made of.
const VertexData = struct {
position: [3]f32,
};
/// Contains the data to render a primitive (3D shape or model).
const PrimitiveData = struct {
/// Vertices describe the "points" that a primitive is made out of.
/// This buffer is of type `[]VertexData`.
vertex_buffer: *gpu.Buffer,
vertex_count: u32,
/// Indices describe what vertices make up the triangles in a primitive.
/// This buffer is of type `[]u32`.
index_buffer: *gpu.Buffer,
index_count: u32,
// For example, `vertex_buffer` may have 4 points defining a square, but
// since it needs to be rendered using 2 triangles, `index_buffer` will
// contain 6 entries, `0, 1, 2` and `3, 2, 1` making up one triangle each.
};
pub const App = @This();
app_timer: core.Timer,
title_timer: core.Timer,
pipeline: *gpu.RenderPipeline,
scene_uniform_buffer: *gpu.Buffer,
scene_bind_group: *gpu.BindGroup,
object_uniform_buffers: [3]*gpu.Buffer,
object_bind_groups: [3]*gpu.BindGroup,
vertex_count: u32,
vertex_buffer: *gpu.Buffer,
object_primitive_indices: [3]usize,
primitives: [2]PrimitiveData,
pub fn init(app: *App) !void {
try core.init(.{});
@ -64,6 +84,11 @@ pub fn init(app: *App) !void {
.entry_point = "frag_main",
.targets = &.{.{ .format = core.descriptor.format }},
}),
.primitive = .{
.topology = .triangle_list,
.front_face = .ccw,
.cull_mode = .back,
},
});
// Set up uniform buffers and bind groups.
@ -74,6 +99,9 @@ pub fn init(app: *App) !void {
.size = @sizeOf(SceneUniformBuffer),
.mapped_at_creation = .false,
});
// "Bind groups" are used to associate data from buffers with shader parameters.
// So for example the `scene_bind_group` is accessible via `scene` in our shader.
// Essentially, buffer = data, and bind group = binding parameter to that data.
app.scene_bind_group = core.device.createBindGroup(
&gpu.BindGroup.Descriptor.init(.{
.layout = app.pipeline.getBindGroupLayout(0),
@ -100,33 +128,90 @@ pub fn init(app: *App) !void {
);
}
// Upload object information (model matrix + color) to the GPU.
const rotation = zm.rotationY(std.math.tau / 2.0);
// The objects are rotated 180° to face the camera, or else we
// would see the back side of the triangles, which are culled.
core.queue.writeBuffer(app.object_uniform_buffers[0], 0, &[_]ObjectUniformBuffer{.{
.model_matrix = zm.transpose(zm.translation(-1.0, 0.25, 0.0)),
.model_matrix = zm.transpose(zm.mul(rotation, zm.translation(-1.0, 0.25, 0.0))),
.color = .{ 1.0, 0.0, 0.0 },
}});
app.object_primitive_indices[0] = 0;
core.queue.writeBuffer(app.object_uniform_buffers[1], 0, &[_]ObjectUniformBuffer{.{
.model_matrix = zm.transpose(zm.translation(0.0, -0.25, 0.0)),
.model_matrix = zm.transpose(zm.mul(rotation, zm.translation(0.0, -0.25, 0.0))),
.color = .{ 0.0, 1.0, 0.0 },
}});
app.object_primitive_indices[1] = 1;
core.queue.writeBuffer(app.object_uniform_buffers[2], 0, &[_]ObjectUniformBuffer{.{
.model_matrix = zm.transpose(zm.translation(1.0, 0.0, 0.0)),
.model_matrix = zm.transpose(zm.mul(rotation, zm.translation(1.0, 0.0, 0.0))),
.color = .{ 0.0, 0.0, 1.0 },
}});
app.object_primitive_indices[2] = 0;
// Set up vertex buffer, containing the vertex data we want to draw.
const vertices = [_]VertexData{
// Set up the primitives we want to render.
// Triangle
app.primitives[0] = createPrimitive(
&.{
.{ .position = .{ 0.0, 0.5, 0.0 } },
.{ .position = .{ 0.5, -0.5, 0.0 } },
.{ .position = .{ -0.5, -0.5, 0.0 } },
},
// Note that the back faces of triangles are "culled", and thus not visible.
// We need to take care to specify the vertices in counter-clock orientation.
&.{
0, 1, 2,
},
);
// Square
app.primitives[1] = createPrimitive(
// 0--2
// | |
// | |
// 1--3
&.{
.{ .position = .{ -0.5, -0.5, 0.0 } },
.{ .position = .{ -0.5, 0.5, 0.0 } },
.{ .position = .{ 0.5, -0.5, 0.0 } },
};
app.vertex_count = vertices.len;
app.vertex_buffer = core.device.createBuffer(&.{
.size = app.vertex_count * @sizeOf(VertexData),
.usage = .{ .vertex = true, .copy_dst = true },
.{ .position = .{ 0.5, 0.5, 0.0 } },
},
// 0--2 4
// | / /|
// |/ / |
// 1 5--3
&.{
0, 1, 2,
3, 2, 1,
},
);
}
/// Creates a buffer on the GPU with the specified usage
/// flags and immediately fills it with the provided data.
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,
});
// Upload vertex buffer to the GPU.
core.queue.writeBuffer(app.vertex_buffer, 0, &vertices);
core.queue.writeBuffer(buffer, 0, data);
return buffer;
}
// Creates a primitive from the provided vertices and indices,
// and uploads the buffers necessary to render it to the GPU.
fn createPrimitive(
vertices: []const VertexData,
indices: []const u32,
) PrimitiveData {
return .{
.vertex_buffer = createAndWriteBuffer(VertexData, vertices, .{ .vertex = true, .copy_dst = true }),
.vertex_count = @intCast(vertices.len),
.index_buffer = createAndWriteBuffer(u32, indices, .{ .index = true, .copy_dst = true }),
.index_count = @intCast(indices.len),
};
}
pub fn deinit(app: *App) void {
@ -138,7 +223,10 @@ pub fn deinit(app: *App) void {
defer app.scene_bind_group.release();
defer for (app.object_uniform_buffers) |b| b.release();
defer for (app.object_bind_groups) |g| g.release();
defer app.vertex_buffer.release();
defer for (app.primitives) |p| {
p.vertex_buffer.release();
p.index_buffer.release();
};
}
pub fn update(app: *App) !bool {
@ -201,13 +289,20 @@ pub fn update(app: *App) !bool {
pass.setPipeline(app.pipeline);
pass.setBindGroup(0, app.scene_bind_group, &.{});
pass.setVertexBuffer(0, app.vertex_buffer, 0, app.vertex_count * @sizeOf(VertexData));
for (app.object_bind_groups) |object_bind_group| {
for (app.object_bind_groups, 0..) |object_bind_group, i| {
// Set the vertex and index buffer used to render this object
// to the primitive it wants to use (either triangle or square).
const primitive_index = app.object_primitive_indices[i];
const primitive = app.primitives[primitive_index];
pass.setVertexBuffer(0, primitive.vertex_buffer, 0, primitive.vertex_count * @sizeOf(VertexData));
pass.setIndexBuffer(primitive.index_buffer, .uint32, 0, primitive.index_count * @sizeOf(u32));
// Set the bind group for an object we want to render.
pass.setBindGroup(1, object_bind_group, &.{});
// Draw the vertices in `vertex_buffer`.
pass.draw(app.vertex_count, 1, 0, 0);
// Draw a number of triangles as specified in the index buffer.
pass.drawIndexed(primitive.index_count, 1, 0, 0, 0);
}
}

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