X-Git-Url: http://nitlanguage.org

diff --git a/lib/gamnit/textures.nit b/lib/gamnit/textures.nit
index 4bc95cb..4383c2b 100644
--- a/lib/gamnit/textures.nit
+++ b/lib/gamnit/textures.nit
@@ -20,7 +20,7 @@ import display
 # Texture composed of pixels, loaded from the assets folder by default
 #
 # Most textures should be created with `App` (as attributes)
-# for the method `on_create` to load them.
+# for the method `create_scene` to load them.
 #
 # ~~~
 # import gamnit::flat
@@ -29,9 +29,9 @@ import display
 #     # Create the texture object, it will be loaded automatically
 #     var texture = new Texture("path/in/assets.png")
 #
-#     redef fun on_create()
+#     redef fun create_scene()
 #     do
-#         # Let `on_create` load the texture
+#         # Let `create_scene` load the texture
 #         super
 #
 #         # Use the texture
@@ -41,7 +41,7 @@ import display
 # end
 # ~~~
 #
-# Otherwise, they can be loaded and error checked explicitly after `on_create`.
+# Otherwise, they can be loaded and error checked explicitly after `create_scene`.
 #
 # ~~~nitish
 # var texture = new Texture("path/in/assets.png")
@@ -80,9 +80,7 @@ abstract class Texture
 	# Prepare a subtexture from this texture, from the given pixel offsets
 	fun subtexture(left, top, width, height: Numeric): Subtexture
 	do
-		# Setup the subtexture
-		var subtex = new Subtexture(root, self, left.to_f, top.to_f, width.to_f, height.to_f)
-		return subtex
+		return new AbsoluteSubtexture(self, left.to_f, top.to_f, width.to_f, height.to_f)
 	end
 
 	# Offset of the left border on `root` from 0.0 to 1.0
@@ -156,10 +154,9 @@ class CustomTexture
 	# The argument `color` should be an array of up to 4 floats (RGBA).
 	# If `color` has less than 4 items, the missing items are replaced by 1.0.
 	#
-	# Require: `not loaded and x < width.to_i and y < height.to_i`
+	# Require: `x < width.to_i and y < height.to_i`
 	fun []=(x, y: Int, color: Array[Float])
 	do
-		assert not loaded else print_error "{class_name}::[]= already loaded"
 		assert x < width.to_i and y < height.to_i else print_error "{class_name}::[] out of bounds"
 
 		# Simple conversion from [0.0..1.0] to [0..255]
@@ -168,18 +165,16 @@ class CustomTexture
 
 		var offset = 4*(x + y*width.to_i)
 		for i in [0..4[ do cpixels[offset+i] = bytes[i]
+
+		loaded = false
 	end
 
-	# Overwrite all pixels with `color`
+	# Overwrite all pixels with `color`, return `self`
 	#
 	# The argument `color` should be an array of up to 4 floats (RGBA).
 	# If `color` has less than 4 items, the missing items are replaced by 1.0.
-	#
-	# Require: `not loaded`
-	fun fill(color: Array[Float])
+	fun fill(color: Array[Float]): SELF
 	do
-		assert not loaded else print_error "{class_name}::fill already loaded"
-
 		# Simple conversion from [0.0..1.0] to [0..255]
 		var bytes = [for c in color do (c*255.0).round.to_i.clamp(0, 255).to_bytes.last]
 		while bytes.length < 4 do bytes.add 255u8
@@ -191,11 +186,21 @@ class CustomTexture
 				i += 4
 			end
 		end
+
+		loaded = false
+		return self
 	end
 
 	redef fun load(force)
 	do
-		if loaded then return
+		force = force or else false
+		if loaded and not force then return
+
+		if force and glIsTexture(gl_texture) then
+			# Was already loaded, free the previous GL name
+			glDeleteTextures([gl_texture])
+		end
+		gl_texture = -1
 
 		# Round down the desired dimension
 		var width = width.to_i
@@ -205,12 +210,11 @@ class CustomTexture
 
 		load_from_pixels(cpixels.native_array, width, height, gl_RGBA)
 
-		cpixels.destroy
 		loaded = true
 	end
 end
 
-# Texture with its own pixels
+# Texture with its own pixel data
 class RootTexture
 	super Texture
 
@@ -223,14 +227,34 @@ class RootTexture
 
 	init do all_root_textures.add self
 
+	# Should the pixels RGB values be premultiplied by their alpha value at loading?
+	#
+	# All gamnit textures must have premultiplied alpha, it provides a better
+	# alpha blending, avoids artifacts and allows for additive blending.
+	#
+	# When at `true`, the default, pixels RGB values are premultiplied
+	# at loading. Set to `false` if pixels RGB values are already
+	# premultiplied in the source data.
+	#
+	# This value must be set before calling `load`.
+	var premultiply_alpha = true is writable
+
 	private fun load_from_pixels(pixels: Pointer, width, height: Int, format: GLPixelFormat)
 	do
 		var max_texture_size = glGetIntegerv(gl_MAX_TEXTURE_SIZE, 0)
-		if width > max_texture_size or height > max_texture_size then
-			error = new Error("Texture {self} width or height is over the GL_MAX_TEXTURE_SIZE of {max_texture_size}")
+		if width > max_texture_size then
+			error = new Error("Texture width larger than gl_MAX_TEXTURE_SIZE ({max_texture_size}) in {self} at {width}")
+			return
+		else if height > max_texture_size then
+			error = new Error("Texture height larger than gl_MAX_TEXTURE_SIZE ({max_texture_size}) in {self} at {height}")
 			return
 		end
 
+		# Premultiply alpha?
+		if premultiply_alpha and format == gl_RGBA then
+			pixels.premultiply_alpha(width, height)
+		end
+
 		glPixelStorei(gl_UNPACK_ALIGNEMENT, 1)
 		var tex = glGenTextures(1)[0]
 		gl_texture = tex
@@ -240,6 +264,9 @@ class RootTexture
 
 		glHint(gl_GENERATE_MIPMAP_HINT, gl_NICEST)
 		glGenerateMipmap(gl_TEXTURE_2D)
+		glTexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MIN_FILTER, gl_LINEAR_MIPMAP_LINEAR)
+
+		glBindTexture(gl_TEXTURE_2D, 0)
 	end
 
 	private fun load_checker(size: Int)
@@ -309,18 +336,25 @@ class TextureAsset
 end
 
 # Texture derived from another texture, does not own its pixels
-class Subtexture
+abstract class Subtexture
 	super Texture
 
-	redef var root
-
 	# Parent texture, from which this texture was created
 	var parent: Texture
 
-	# Left border of this texture compared to `parent`
+	redef fun root do return parent.root
+
+	redef fun load(force) do root.load(force)
+end
+
+# Subtexture created from pixel coordinates within `parent`
+class AbsoluteSubtexture
+	super Subtexture
+
+	# Left border of this texture relative to `parent`
 	var left: Float
 
-	# Top border of this texture compared to `parent`
+	# Top border of this texture relative to `parent`
 	var top: Float
 
 	private fun set_wh(width, height: Float)
@@ -329,14 +363,25 @@ class Subtexture
 		self.height = height
 	end
 
-	redef fun load(force) do root.load(force)
-
 	redef var offset_left = parent.offset_left + left / root.width is lazy
 	redef var offset_top = parent.offset_top + top / root.height is lazy
 	redef var offset_right = offset_left + width / root.width is lazy
 	redef var offset_bottom = offset_top + height / root.height is lazy
 end
 
+# Subtexture created from relative coordinates ([0..1]) out of the `root` texture
+class RelativeSubtexture
+	super Subtexture
+
+	redef var offset_left
+	redef var offset_top
+	redef var offset_right
+	redef var offset_bottom
+
+	redef fun width do return root.width * (offset_right - offset_left)
+	redef fun height do return root.height * (offset_bottom - offset_top)
+end
+
 redef class Sys
 	# All declared root textures
 	var all_root_textures = new TextureSet
@@ -349,3 +394,20 @@ class TextureSet
 	# Load all texture of this set
 	fun load_all do for t in self do t.load
 end
+
+redef class Pointer
+	# Multiply RGB values by their alpha value
+	private fun premultiply_alpha(width, height: Int) `{
+		uint8_t *bytes = (uint8_t *)self;
+		int x, y, i = 0;
+		for(y = 0; y < height; y ++) {
+			for(x = 0; x < width; x ++) {
+				int a = bytes[i+3];
+				bytes[i  ] = bytes[i  ] * a / 255;
+				bytes[i+1] = bytes[i+1] * a / 255;
+				bytes[i+2] = bytes[i+2] * a / 255;
+				i += 4;
+			}
+		}
+	`}
+end