gamnit: leave it up to the clients to set premultiplied colors in Materials

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 746a952..3b320f9 100644 (file)
--- a/lib/gamnit/depth/more_materials.nit
+++ b/lib/gamnit/depth/more_materials.nit
@@ -31,12 +31,18 @@ class SmoothMaterial
        super Material
 
        # Ambient color, always visible
+       #
+       # The RGB values should be premultiplied by the alpha value.
        var ambient_color: Array[Float] is writable
 
        # Diffuse color when covered by a light source
+       #
+       # The RGB values should be premultiplied by the alpha value.
        var diffuse_color: Array[Float] is writable
 
        # Specular color affecting reflections
+       #
+       # The RGB values should be premultiplied by the alpha value.
        var specular_color: Array[Float] is writable
 
        redef fun draw(actor, model)
@@ -71,9 +77,13 @@ class SmoothMaterial
                program.camera.uniform(app.world_camera.position.x, app.world_camera.position.y, app.world_camera.position.z)
 
                # Colors from the material
-               program.ambient_color.uniform(ambient_color[0], ambient_color[1], ambient_color[2], ambient_color[3]*actor.alpha)
-               program.diffuse_color.uniform(diffuse_color[0], diffuse_color[1], diffuse_color[2], diffuse_color[3]*actor.alpha)
-               program.specular_color.uniform(specular_color[0], specular_color[1], specular_color[2], specular_color[3]*actor.alpha)
+               var a = actor.alpha
+               program.ambient_color.uniform(ambient_color[0]*a, ambient_color[1]*a,
+                                             ambient_color[2]*a, ambient_color[3]*a)
+               program.diffuse_color.uniform(diffuse_color[0]*a, diffuse_color[1]*a,
+                                             diffuse_color[2]*a, diffuse_color[3]*a)
+               program.specular_color.uniform(specular_color[0]*a, specular_color[1]*a,
+                                              specular_color[2]*a, specular_color[3]*a)
 
                # Execute draw
                if mesh.indices.is_empty then
@@ -188,9 +198,13 @@ class TexturedMaterial
 
                program.rotation.uniform new Matrix.gamnit_euler_rotation(actor.pitch, actor.yaw, actor.roll)
 
-               program.ambient_color.uniform(ambient_color[0], ambient_color[1], ambient_color[2], ambient_color[3]*actor.alpha)
-               program.diffuse_color.uniform(diffuse_color[0], diffuse_color[1], diffuse_color[2], diffuse_color[3]*actor.alpha)
-               program.specular_color.uniform(specular_color[0], specular_color[1], specular_color[2], specular_color[3]*actor.alpha)
+               var a = actor.alpha
+               program.ambient_color.uniform(ambient_color[0]*a, ambient_color[1]*a,
+                                             ambient_color[2]*a, ambient_color[3]*a)
+               program.diffuse_color.uniform(diffuse_color[0]*a, diffuse_color[1]*a,
+                                             diffuse_color[2]*a, diffuse_color[3]*a)
+               program.specular_color.uniform(specular_color[0]*a, specular_color[1]*a,
+                                              specular_color[2]*a, specular_color[3]*a)
 
                program.normal.array_enabled = true
                program.normal.array(mesh.normals, 3)