Blend file: Use alpha blending flag, add alpha in principled & teximage nodes.

src/loaders/blend.nim

@@ -306,7 +306,7 @@ proc loadObjectImpl(self: BlendLoader, scene: Scene, obn: FNode): (GameObject, s
         ob.passes.setLen mat_count
         var tangents: seq[string]
         for i in 0 ..< mat_count:
-            assert i < 16, "More than 16 materials not supported yet"
+            assert i < 16, "More than 16 materials not supported yet" # TODO
             let is_oblink = matbits[i].testBit(0)
             let mat = if is_oblink:
                 obn.mat[i]
@@ -318,6 +318,10 @@ proc loadObjectImpl(self: BlendLoader, scene: Scene, obn: FNode): (GameObject, s
                 continue
             
             var backface_culling = (mat.blend_flag.i8[0] and 4'i8) != 0
+            let blend_method = mat.blend_method.i8[0]
+            let alpha_blend = blend_method == 5
+            if alpha_blend:
+                ob.passes[i] = 1
 
             # this gives the "sons" error
             # dump (mat.id.name.cstr.strip2, backface_culling)

src/loaders/blend_nodes.nim

@@ -642,7 +642,7 @@ node_functions = {
         let s = texture_uniform(img.name.str.strip2)
         var v = ins["Vector"].uv_socket
         # TODO: output float directly from single channel textures
-        return mkOutput(&"$0 = texture({s}, {vec2(v)});", vec4tmp())
+        return mkOutput(&"$0 = texture({s}, {vec2(v)});$1 = $0.a;", vec4tmp(), flttmp())
     ,
     "ShaderNodeTexEnvironment": proc(ins: InputMapper): seq[Expr] {.closure.} =
         let img = ins.node.id
@@ -1015,7 +1015,7 @@ node_functions = {
         let metallic = ins["Metallic"].flt
         let roughness = ins["Roughness"].flt
         let ior = ins["IOR"].flt
-        # let alpha = ins["Alpha"].flt
+        let alpha = ins["Alpha"].flt
         let normal = ins["Normal"].normal_socket_to_world
         # let weight1 = ins["Weight"].flt
         # let subsurface_weight = ins["Subsurface Weight"].flt
@@ -1047,7 +1047,8 @@ node_functions = {
             &"{world_position()}, " &
             &"{metallic}, " &
             &"{roughness}, " &
-            &"{ior} " &
+            &"{ior}, " &
+            &"{alpha} " &
             &") + vec4({emission_color} * {emission_strength}, 0.0);", vec4tmp())
     ,
     "ShaderNodeRGBCurve": proc(ins: InputMapper): seq[Expr] {.closure.} =

src/shaders/shader_library.glsl

@@ -205,7 +205,8 @@ vec4 diffuse_node(vec3 base, vec3 I, vec3 normal, vec3 pos){
     return vec4(color, 1.0);
 }
 
-vec4 principled_node(vec3 base, vec3 I, vec3 normal, vec3 pos, float metallic, float roughness, float ior){
+vec4 principled_node(vec3 base, vec3 I, vec3 normal, vec3 pos, float metallic,
+                    float roughness, float ior, float alpha){
     vec3 N = normal;
 #if FIX_BORDERS
     float dotNI = dot(N, I);
@@ -293,7 +294,7 @@ vec4 principled_node(vec3 base, vec3 I, vec3 normal, vec3 pos, float metallic, f
     // color += mix(env_diffuse, env_specular, F);
     // adding instead of mixing because F is already in diffuse
     color += diffuse * env_diffuse + F * env_specular;
-    return vec4(color, 1.0);
+    return vec4(color, alpha);
 }
 
 vec3 refraction_dominant_dir(vec3 N, vec3 V, float roughness, float ior)