commit c9e1982d1c17009e899e13b0805745074075a4f7
Author: shylie <shylie@shylie.info>
Date:   Mon Jul 14 12:56:11 2025 -0400

    Initial commit

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..53dde2b
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,20 @@
+Copyright (c) 2025 shylie
+
+This software is provided ‘as-is’, without any express or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not
+claim that you wrote the original software. If you use this software
+in a product, an acknowledgment in the product documentation would be
+appreciated but is not required.
+
+2. Altered source versions must be plainly marked as such, and must not be
+misrepresented as being the original software.
+
+3. This notice may not be removed or altered from any source
+distribution.
diff --git a/main.lua b/main.lua
new file mode 100644
index 0000000..b07c0fd
--- /dev/null
+++ b/main.lua
@@ -0,0 +1,32 @@
+local tex = love.graphics.newImage("mrmo3x.png")
+tex:setFilter("nearest", "nearest")
+
+local function color(layer)
+	if layer < 27 then
+		return layer / 31 / 2.5, layer / 62 / 2.5, 0.1
+	else
+		return 0.05, (layer - 27) / 10 + 0.3, 0.05
+	end
+end
+
+local BIG_BLOCK = love.graphics.newQuad(24 * 9, 24 * 9, 24, 24, tex)
+
+local z = require("zprite").new(tex, 65536)
+z._height_scale = 6
+
+for i = 1, 32 do
+	for j = 1, 32 do
+		local layers = love.math.noise(i * 0.1, j * 0.1) * 20 + 12
+		z:put(i * 24, j * 24, BIG_BLOCK, math.floor(layers) + 1, color)
+	end
+end
+
+local angle = 0
+
+function love.update(dt)
+	angle = math.fmod(angle + dt * 1.2, 2 * math.pi)
+end
+
+function love.draw()
+	z:draw(love.graphics.getWidth() / 2, love.graphics.getHeight() / 2 + 32, angle, 0.6, 0.6, 24 * 32 / 2, 24 * 32 / 2)
+end
diff --git a/zprite/init.lua b/zprite/init.lua
new file mode 100644
index 0000000..ad5e7fa
--- /dev/null
+++ b/zprite/init.lua
@@ -0,0 +1,150 @@
+---@class zprite
+---@field _texture love.Image
+---@field _instance_vertex_count integer
+---@field _mesh love.Mesh
+---@field _instance_mesh love.Mesh
+---@field _instances {}[]
+---@field _height_scale number
+---@field _changed boolean
+local zprite = {}
+zprite.__index = zprite
+
+local ZPRITE_SHADER = love.graphics.newShader([[
+varying vec4 VsColorOut;
+
+#ifdef VERTEX
+attribute vec2 InstancePosition;
+attribute vec2 InstanceTextureOffset;
+attribute vec2 InstanceScale;
+attribute float InstanceLayer;
+attribute vec4 InstanceColor;
+
+uniform float HeightScale;
+
+vec4 position(mat4 transform_projection, vec4 vertex_position)
+{
+  vertex_position.xy *= InstanceScale;
+  vertex_position.xy += InstancePosition.xy;
+  vertex_position.z = InstanceLayer / 1024;
+  VaryingTexCoord.xy *= InstanceScale;
+  VaryingTexCoord.xy += InstanceTextureOffset;
+  VsColorOut = InstanceColor;
+  return (transform_projection * vertex_position) + vec4(0, (InstanceLayer * HeightScale) / love_ScreenSize.y, 0, 0);
+}
+#endif
+
+#ifdef PIXEL
+vec4 effect(vec4 color, Image tex, vec2 texture_coords, vec2 screen_coords)
+{
+  vec4 texture_color = Texel(tex, texture_coords);
+  return texture_color * color * VsColorOut;
+}
+#endif
+]])
+
+local function ZPRITE_DEFAULT_COLORMAP(_)
+	return 1, 1, 1, 1
+end
+
+---@param texture love.Image
+---@param max_instances integer?
+function zprite.new(texture, max_instances)
+	if not texture then
+		error("texture cannot be nil")
+	end
+	if max_instances and max_instances < 1 then
+		error("max_instances cannot be less than 1")
+	end
+
+	local tw, th = texture:getPixelDimensions()
+	local vertices = {
+		{ 0, 0, 0, 0 },
+		{ 1, 0, 1 / tw, 0 },
+		{ 0, 1, 0, 1 / th },
+		{ 1, 1, 1 / tw, 1 / th },
+	}
+
+	local obj = setmetatable({}, zprite)
+
+	obj._texture = texture
+	obj._instance_vertex_count = max_instances or 16384
+	obj._mesh = love.graphics.newMesh(
+		{ { "VertexPosition", "float", 2 }, { "VertexTexCoord", "float", 2 } },
+		vertices,
+		"strip",
+		"static"
+	)
+	obj._mesh:setTexture(texture)
+	obj._instance_mesh = love.graphics.newMesh({
+		{ "InstancePosition", "float", 2 },
+		{ "InstanceTextureOffset", "float", 2 },
+		{ "InstanceScale", "float", 2 },
+		{ "InstanceLayer", "float", 1 },
+		{ "InstanceColor", "float", 4 },
+	}, obj._instance_vertex_count, nil, "dynamic")
+	obj._instances = {}
+	obj._height_scale = 4
+	obj._changed = false
+
+	obj._mesh:attachAttribute("InstancePosition", obj._instance_mesh, "perinstance")
+	obj._mesh:attachAttribute("InstanceTextureOffset", obj._instance_mesh, "perinstance")
+	obj._mesh:attachAttribute("InstanceScale", obj._instance_mesh, "perinstance")
+	obj._mesh:attachAttribute("InstanceLayer", obj._instance_mesh, "perinstance")
+	obj._mesh:attachAttribute("InstanceColor", obj._instance_mesh, "perinstance")
+
+	return obj
+end
+
+--- Clear all drawn objects
+function zprite:clear()
+	-- no need to set _changed to true, as #self._instances will be 0
+	self._instances = {}
+end
+
+--- Add an 'entity' to be rendered
+---@param x number
+---@param y number
+---@param quad love.Quad
+---@param layer_count integer
+---@param color_map function?
+---@param base_layer integer?
+function zprite:put(x, y, quad, layer_count, color_map, base_layer)
+	if #self._instances + layer_count > self._instance_vertex_count then
+		return
+	end
+
+	base_layer = base_layer or 0
+	color_map = color_map or ZPRITE_DEFAULT_COLORMAP
+
+	self._changed = true
+
+	local qx, qy, qw, qh = quad:getViewport()
+	local tw, th = self._texture:getPixelDimensions()
+
+	for i = 1, layer_count do
+		local r, g, b, a = color_map(i)
+		if not a then
+			a = 1
+		end
+		table.insert(self._instances, { x, y, qx / tw, qy / th, qw, qh, i + base_layer, r, g, b, a })
+	end
+end
+
+--- Draw to the screen / current canvas
+---@overload fun(self, x: number, y: number, r: number?, sx: number?, sy: number?, ox: number?, oy: number?, kx: number?, ky: number?)
+---@overload fun(self, transform: love.Transform)
+function zprite:draw(...)
+	love.graphics.setDepthMode("less", true)
+
+	love.graphics.setShader(ZPRITE_SHADER)
+	ZPRITE_SHADER:send("HeightScale", self._height_scale)
+
+	if self._changed then
+		self._instance_mesh:setVertices(self._instances)
+		self._changed = false
+	end
+
+	love.graphics.drawInstanced(self._mesh, #self._instances, ...)
+end
+
+return zprite