From: Alexis Laferrière <alexis.laf@xymus.net>
Date: Thu, 21 Jan 2016 16:28:08 +0000 (-0500)
Subject: lib/gamnit depth: TextureMaterial supports subtexture
X-Git-Tag: v0.8~7^2~12
X-Git-Url: http://nitlanguage.org

lib/gamnit depth: TextureMaterial supports subtexture

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
---

diff --git a/lib/gamnit/depth/more_materials.nit b/lib/gamnit/depth/more_materials.nit
index 453c7e4..27bdd9a 100644
--- a/lib/gamnit/depth/more_materials.nit
+++ b/lib/gamnit/depth/more_materials.nit
@@ -102,7 +102,8 @@ class TexturedMaterial
 		var program = app.versatile_program
 		program.use
 
-		var need_tex_coord = false
+		# One of the textures used, if any
+		var sample_used_texture = null
 
 		var texture = ambient_texture
 		if texture != null then
@@ -110,7 +111,7 @@ class TexturedMaterial
 			glBindTexture(gl_TEXTURE_2D, texture.gl_texture)
 			program.use_map_ambient.uniform true
 			program.map_ambient.uniform 0
-			need_tex_coord = true
+			sample_used_texture = texture
 		else
 			program.use_map_ambient.uniform false
 		end
@@ -121,7 +122,7 @@ class TexturedMaterial
 			glBindTexture(gl_TEXTURE_2D, texture.gl_texture)
 			program.use_map_diffuse.uniform true
 			program.map_diffuse.uniform 1
-			need_tex_coord = true
+			sample_used_texture = texture
 		else
 			program.use_map_diffuse.uniform false
 		end
@@ -132,7 +133,7 @@ class TexturedMaterial
 			glBindTexture(gl_TEXTURE_2D, texture.gl_texture)
 			program.use_map_specular.uniform true
 			program.map_specular.uniform 2
-			need_tex_coord = true
+			sample_used_texture = texture
 		else
 			program.use_map_specular.uniform false
 		end
@@ -140,8 +141,29 @@ class TexturedMaterial
 		program.translation.uniform(actor.center.x, actor.center.y, actor.center.z, 0.0)
 		program.scale.uniform actor.scale
 
-		program.tex_coord.array_enabled = need_tex_coord
-		program.tex_coord.array(mesh.texture_coords, 2)
+		# If using a texture, set `texture_coords`
+		program.tex_coord.array_enabled = sample_used_texture != null
+		if sample_used_texture != null then
+			if sample_used_texture isa GamnitRootTexture then
+				# Coordinates are directly valid
+				program.tex_coord.array(mesh.texture_coords, 2)
+			else
+				# Correlate texture coordinates from the substexture and the mesh.
+				# This is slow, but should be cached on the GPU.
+				var xa = sample_used_texture.offset_left
+				var xd = sample_used_texture.offset_right - xa
+				var ya = sample_used_texture.offset_top
+				var yd = sample_used_texture.offset_bottom - ya
+
+				var tex_coords = new Array[Float].with_capacity(mesh.texture_coords.length)
+				for i in [0..mesh.texture_coords.length/2[ do
+					tex_coords[i*2]   = xa + xd * mesh.texture_coords[i*2]
+					tex_coords[i*2+1] = ya + yd * mesh.texture_coords[i*2+1]
+				end
+
+				program.tex_coord.array(tex_coords, 2)
+			end
+		end
 
 		program.coord.array_enabled = true
 		program.coord.array(mesh.vertices, 3)