Add option to use texture alpha channel

client/shaders/test_shader_3/base.txt

@@ -0,0 +1 @@
+trans_alphach

client/shaders/test_shader_3/opengl_fragment.glsl

@@ -0,0 +1,23 @@
+
+uniform sampler2D myTexture;
+uniform float fogDistance;
+
+varying vec3 vPosition;
+
+void main (void)
+{
+	vec4 col = texture2D(myTexture, vec2(gl_TexCoord[0]));
+	col *= gl_Color;
+	col = col * col; // SRGB -> Linear
+	col *= 1.8;
+	col.r = 1.0 - exp(1.0 - col.r) / exp(1.0);
+	col.g = 1.0 - exp(1.0 - col.g) / exp(1.0);
+	col.b = 1.0 - exp(1.0 - col.b) / exp(1.0);
+	col = sqrt(col); // Linear -> SRGB
+	float a = col.a;
+	if(fogDistance != 0.0){
+		float d = max(0.0, min(vPosition.z / fogDistance * 1.5 - 0.6, 1.0));
+		a = mix(a, 0.0, d);
+	}
+	gl_FragColor = vec4(col.r, col.g, col.b, a);
+}

client/shaders/test_shader_3/opengl_vertex.glsl

@@ -0,0 +1,51 @@
+
+uniform mat4 mWorldViewProj;
+uniform mat4 mInvWorld;
+uniform mat4 mTransWorld;
+uniform float dayNightRatio;
+
+varying vec3 vPosition;
+
+void main(void)
+{
+	gl_Position = mWorldViewProj * gl_Vertex;
+
+	vPosition = (mWorldViewProj * gl_Vertex).xyz;
+
+	vec4 color;
+	//color = vec4(1.0, 1.0, 1.0, 1.0);
+
+	float day = gl_Color.r;
+	float night = gl_Color.g;
+	float light_source = gl_Color.b;
+
+	/*color.r = mix(night, day, dayNightRatio);
+	color.g = color.r;
+	color.b = color.r;*/
+
+	float rg = mix(night, day, dayNightRatio);
+	rg += light_source * 1.0; // Make light sources brighter
+	float b = rg;
+
+	// Moonlight is blue
+	b += (day - night) / 13.0;
+	rg -= (day - night) / 13.0;
+
+	// Emphase blue a bit in darker places
+	// See C++ implementation in mapblock_mesh.cpp finalColorBlend()
+	b += max(0.0, (1.0 - abs(b - 0.13)/0.17) * 0.025);
+
+	// Artificial light is yellow-ish
+	// See C++ implementation in mapblock_mesh.cpp finalColorBlend()
+	rg += max(0.0, (1.0 - abs(rg - 0.85)/0.15) * 0.065);
+
+	color.r = rg;
+	color.g = rg;
+	color.b = b;
+
+	color.a = gl_Color.a;
+
+	gl_FrontColor = gl_BackColor = color;
+
+	gl_TexCoord[0] = gl_MultiTexCoord0;
+}

doc/lua_api.txt

@@ -1649,6 +1649,7 @@ Node definition (register_node)
     ^ Special textures of node; used rarely (old field name: special_materials)
     ^ List can be shortened to needed length
     alpha = 255,
+    use_texture_alpha = false, -- Use texture's alpha channel
     post_effect_color = {a=0, r=0, g=0, b=0}, -- If player is inside node
     paramtype = "none", -- See "Nodes"
     paramtype2 = "none", -- See "Nodes"

src/mapblock_mesh.cpp

@@ -1099,6 +1099,8 @@ MapBlockMesh::MapBlockMesh(MeshMakeData *data):
 			getShader("test_shader_1").material;
 	video::E_MATERIAL_TYPE shadermat2 = m_gamedef->getShaderSource()->
 			getShader("test_shader_2").material;
+	video::E_MATERIAL_TYPE shadermat3 = m_gamedef->getShaderSource()->
+			getShader("test_shader_3").material;
 	for(u32 i = 0; i < collector.prebuffers.size(); i++)
 	{
 		PreMeshBuffer &p = collector.prebuffers[i];
@@ -1174,7 +1176,7 @@ MapBlockMesh::MapBlockMesh(MeshMakeData *data):
 				= video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
 		material.setTexture(0, p.tile.texture.atlas);
 		if(enable_shaders)
-			p.tile.applyMaterialOptionsWithShaders(material, shadermat1, shadermat2);
+			p.tile.applyMaterialOptionsWithShaders(material, shadermat1, shadermat2, shadermat3);
 		else
 			p.tile.applyMaterialOptions(material);
 

src/nodedef.cpp

@@ -658,15 +658,11 @@ public:
 				break;
 			}
 
-			u8 material_type = 0;
-			if(is_liquid){
-				if(f->alpha == 255)
-					material_type = TILE_MATERIAL_LIQUID_OPAQUE;
-				else
-					material_type = TILE_MATERIAL_LIQUID_TRANSPARENT;
-			} else{
-				material_type = TILE_MATERIAL_BASIC;
-			}
+			u8 material_type;
+			if (is_liquid)
+				material_type = (f->alpha == 255) ? TILE_MATERIAL_LIQUID_OPAQUE : TILE_MATERIAL_LIQUID_TRANSPARENT;
+			else
+				material_type = (f->alpha == 255) ? TILE_MATERIAL_BASIC : TILE_MATERIAL_ALPHA;
 
 			// Tiles (fill in f->tiles[])
 			for(u16 j=0; j<6; j++){

src/scriptapi_content.cpp

@@ -226,6 +226,11 @@ ContentFeatures read_content_features(lua_State *L, int index)
 
 	f.alpha = getintfield_default(L, index, "alpha", 255);
 	
+	bool usealpha = getboolfield_default(L, index,
+						"use_texture_alpha", false);
+	if (usealpha)
+		f.alpha = 0;
+
 	/* Other stuff */
 
 	lua_getfield(L, index, "post_effect_color");

src/tile.h

@@ -162,6 +162,7 @@ IWritableTextureSource* createTextureSource(IrrlichtDevice *device);
 
 enum MaterialType{
 	TILE_MATERIAL_BASIC,
+	TILE_MATERIAL_ALPHA,
 	TILE_MATERIAL_LIQUID_TRANSPARENT,
 	TILE_MATERIAL_LIQUID_OPAQUE,
 };
@@ -222,6 +223,9 @@ struct TileSpec
 		case TILE_MATERIAL_BASIC:
 			material.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
 			break;
+		case TILE_MATERIAL_ALPHA:
+			material.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL;
+			break;
 		case TILE_MATERIAL_LIQUID_TRANSPARENT:
 			material.MaterialType = video::EMT_TRANSPARENT_VERTEX_ALPHA;
 			break;
@@ -233,12 +237,16 @@ struct TileSpec
 	}
 	void applyMaterialOptionsWithShaders(video::SMaterial &material,
 			const video::E_MATERIAL_TYPE &basic,
-			const video::E_MATERIAL_TYPE &liquid) const
+			const video::E_MATERIAL_TYPE &liquid,
+			const video::E_MATERIAL_TYPE &alpha) const
 	{
 		switch(material_type){
 		case TILE_MATERIAL_BASIC:
 			material.MaterialType = basic;
 			break;
+		case TILE_MATERIAL_ALPHA:
+			material.MaterialType = alpha;
+			break;
 		case TILE_MATERIAL_LIQUID_TRANSPARENT:
 			material.MaterialType = liquid;
 			break;