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Add GPU instance setup

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This commit is contained in:
Jared Miller 2025-12-15 21:59:48 -05:00
parent faeb366bfb
commit 3a54b0dde3
1 changed files with 95 additions and 27 deletions
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122
src/sandbox_main.zig
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@ -16,6 +16,7 @@ const CYAN = rl.Color{ .r = 0, .g = 255, .b = 255, .a = 255 };
// entity rendering
const ENTITY_RADIUS: f32 = 4.0;
const TEXTURE_SIZE: i32 = 16; // must be >= 2 * radius
const MESH_SIZE: f32 = @floatFromInt(TEXTURE_SIZE); // match texture size
// logging thresholds
const TARGET_FRAME_MS: f32 = 16.7; // 60fps
@ -129,15 +130,38 @@ fn createCircleTexture() ?rl.Texture2D {
return target.texture;
}
fn createOrthoCamera() rl.Camera3D {
// orthographic camera looking down -Y axis at XZ plane
// positioned to match 2D screen coordinates
const hw = @as(f32, @floatFromInt(SCREEN_WIDTH)) / 2.0;
const hh = @as(f32, @floatFromInt(SCREEN_HEIGHT)) / 2.0;
return .{
.position = .{ .x = hw, .y = 1000, .z = hh },
.target = .{ .x = hw, .y = 0, .z = hh },
.up = .{ .x = 0, .y = 0, .z = -1 }, // -Z is up to match screen Y
.fovy = @floatFromInt(SCREEN_HEIGHT), // ortho uses fovy as height
.projection = .orthographic,
};
}
fn createInstanceMaterial(texture: rl.Texture2D) ?rl.Material {
var material = rl.loadMaterialDefault() catch return null;
rl.setMaterialTexture(&material, rl.MATERIAL_MAP_DIFFUSE, texture);
return material;
}
pub fn main() !void {
// parse args
var bench_mode = false;
var use_instancing = false;
var args = try std.process.argsWithAllocator(std.heap.page_allocator);
defer args.deinit();
_ = args.skip(); // skip program name
while (args.next()) |arg| {
if (std.mem.eql(u8, arg, "--bench")) {
bench_mode = true;
} else if (std.mem.eql(u8, arg, "--gpu")) {
use_instancing = true;
}
}
@ -162,6 +186,36 @@ pub fn main() !void {
};
defer rl.unloadTexture(circle_texture);
// GPU instancing setup (only if --gpu flag)
var quad_mesh: ?rl.Mesh = null;
var instance_material: ?rl.Material = null;
var ortho_camera: rl.Camera3D = undefined;
// static buffer for transforms - allocated once, reused each frame
var transforms: [sandbox.MAX_ENTITIES]rl.Matrix = undefined;
if (use_instancing) {
// create quad mesh (XZ plane, will view from above)
quad_mesh = rl.genMeshPlane(MESH_SIZE, MESH_SIZE, 1, 1);
rl.uploadMesh(&quad_mesh.?, false); // upload to GPU
// material with circle texture
instance_material = createInstanceMaterial(circle_texture) orelse {
std.debug.print("failed to create instance material\n", .{});
return;
};
// orthographic camera for 2D-like rendering
ortho_camera = createOrthoCamera();
std.debug.print("GPU instancing mode enabled\n", .{});
}
defer {
if (quad_mesh) |*m| rl.unloadMesh(m.*);
if (instance_material) |mat| mat.unload();
}
// load UI font (embedded)
const font_data = @embedFile("verdanab.ttf");
const ui_font = rl.loadFontFromMemory(".ttf", font_data, 32, null) catch {
@ -242,39 +296,53 @@ pub fn main() !void {
rl.beginDrawing();
rl.clearBackground(BG_COLOR);
// draw entities using rlgl quad batching
const size = @as(f32, @floatFromInt(TEXTURE_SIZE));
const half = size / 2.0;
if (use_instancing) {
// GPU instancing path
// fill transforms array with entity positions
for (entities.items[0..entities.count], 0..) |entity, i| {
// entity (x, y) maps to 3D (x, 0, y) on XZ plane
transforms[i] = rl.Matrix.translate(entity.x, 0, entity.y);
}
rl.gl.rlSetTexture(circle_texture.id);
rl.gl.rlBegin(rl.gl.rl_quads);
// draw all entities with single instanced call
ortho_camera.begin();
rl.drawMeshInstanced(quad_mesh.?, instance_material.?, transforms[0..entities.count]);
ortho_camera.end();
} else {
// rlgl quad batching path (original)
const size = @as(f32, @floatFromInt(TEXTURE_SIZE));
const half = size / 2.0;
for (entities.items[0..entities.count]) |entity| {
// extract RGB from entity color (0xRRGGBB)
const r: u8 = @truncate(entity.color >> 16);
const g: u8 = @truncate(entity.color >> 8);
const b: u8 = @truncate(entity.color);
rl.gl.rlColor4ub(r, g, b, 255);
rl.gl.rlSetTexture(circle_texture.id);
rl.gl.rlBegin(rl.gl.rl_quads);
const x1 = entity.x - half;
const y1 = entity.y - half;
const x2 = entity.x + half;
const y2 = entity.y + half;
for (entities.items[0..entities.count]) |entity| {
// extract RGB from entity color (0xRRGGBB)
const r: u8 = @truncate(entity.color >> 16);
const g: u8 = @truncate(entity.color >> 8);
const b: u8 = @truncate(entity.color);
rl.gl.rlColor4ub(r, g, b, 255);
// quad vertices: bottom-left, bottom-right, top-right, top-left
rl.gl.rlTexCoord2f(0, 0);
rl.gl.rlVertex2f(x1, y2);
rl.gl.rlTexCoord2f(1, 0);
rl.gl.rlVertex2f(x2, y2);
rl.gl.rlTexCoord2f(1, 1);
rl.gl.rlVertex2f(x2, y1);
rl.gl.rlTexCoord2f(0, 1);
rl.gl.rlVertex2f(x1, y1);
const x1 = entity.x - half;
const y1 = entity.y - half;
const x2 = entity.x + half;
const y2 = entity.y + half;
// quad vertices: bottom-left, bottom-right, top-right, top-left
rl.gl.rlTexCoord2f(0, 0);
rl.gl.rlVertex2f(x1, y2);
rl.gl.rlTexCoord2f(1, 0);
rl.gl.rlVertex2f(x2, y2);
rl.gl.rlTexCoord2f(1, 1);
rl.gl.rlVertex2f(x2, y1);
rl.gl.rlTexCoord2f(0, 1);
rl.gl.rlVertex2f(x1, y1);
}
rl.gl.rlEnd();
rl.gl.rlSetTexture(0);
}
rl.gl.rlEnd();
rl.gl.rlSetTexture(0);
// metrics overlay (skip in bench mode for cleaner headless run)
if (!bench_mode) {
ui.drawMetrics(&entities, update_time_us, render_time_us, paused, ui_font);