diff --git a/data/shaders/default.frag b/data/shaders/default.frag
index 83c67c35fbc..3282174ce12 100644
--- a/data/shaders/default.frag
+++ b/data/shaders/default.frag
@@ -1,14 +1,17 @@
 #version 120
 
 varying vec4 color_mod;
+varying vec4 color_draw;
 varying vec2 pos;
+varying float submerge_amount;
 uniform sampler2D tex;
 
 void main()
 {
-	float rmod = color_mod.r > 0.5 ? color_mod.r - 1 : color_mod.r;
+/*	float rmod = color_mod.r > 0.5 ? color_mod.r - 1 : color_mod.r;
 	float gmod = color_mod.g > 0.5 ? color_mod.g - 1 : color_mod.g;
 	float bmod = color_mod.b > 0.5 ? color_mod.b - 1 : color_mod.b;
 	float amod = color_mod.a > 0.5 ? color_mod.a - 1 : color_mod.a;
-	gl_FragColor = texture2D(tex, pos) + vec4(rmod, gmod, bmod, amod);
+	gl_FragColor = texture2D(tex, pos) + vec4(rmod, gmod, bmod, amod);*/
+	gl_FragColor = texture2D(tex, pos) + color_mod + color_draw;
 }
diff --git a/data/shaders/default.vert b/data/shaders/default.vert
index e2e2f36b870..daba5a8456b 100644
--- a/data/shaders/default.vert
+++ b/data/shaders/default.vert
@@ -1,17 +1,24 @@
 #version 120
 
-attribute vec4 color;
+// Required by SDL_gpu
+attribute vec4 draw_color;
 attribute vec3 vertex;
 attribute vec2 texture_pos;
+attribute vec4 color;
+attribute float submerge;
 
 uniform mat4 model_view_proj;
 
 varying vec4 color_mod;
 varying vec2 pos;
+varying float submerge_amount;
+varying vec4 color_draw;
 
 void main()
 {
 	pos = texture_pos;
 	color_mod = color;
+	color_draw = draw_color;
+	submerge_amount = submerge;
 	gl_Position = model_view_proj * vec4(vertex, 1.0);
 }
diff --git a/src/sdl/shader.cpp b/src/sdl/shader.cpp
index 2e9a151c981..3ab241ab143 100644
--- a/src/sdl/shader.cpp
+++ b/src/sdl/shader.cpp
@@ -23,6 +23,8 @@ shader_program::shader_program(const std::string &vsrc, const std::string &fsrc)
 	, vertex_object_(0)
 	, fragment_object_(0)
 	, block_()
+	, attr_color_mod_(0)
+	, attr_submerge_(0)
 	, refcount_(new unsigned(1))
 {
 	vertex_object_ = GPU_LoadShader(GPU_VERTEX_SHADER, vsrc.c_str());
@@ -39,12 +41,18 @@ shader_program::shader_program(const std::string &vsrc, const std::string &fsrc)
 	if (!program_object_) {
 		//TODO: report error
 	}
+
+	attr_color_mod_ = GPU_GetAttributeLocation(program_object_, "color");
+	set_color_mod(0, 0, 0, 0);
 }
 
 shader_program::shader_program()
 	: program_object_(0)
 	, vertex_object_(0)
 	, fragment_object_(0)
+	, block_()
+	, attr_color_mod_(0)
+	, attr_submerge_(0)
 	, refcount_(new unsigned(1))
 {}
 
@@ -63,6 +71,9 @@ shader_program::shader_program(const shader_program &prog)
 	: program_object_(prog.program_object_)
 	, vertex_object_(prog.vertex_object_)
 	, fragment_object_(prog.fragment_object_)
+	, block_(prog.block_)
+	, attr_color_mod_(prog.attr_color_mod_)
+	, attr_submerge_(prog.attr_submerge_)
 	, refcount_(prog.refcount_)
 {
 	(*refcount_)++;
@@ -81,7 +92,7 @@ const shader_program &shader_program::operator =(const shader_program &prog)
 void shader_program::activate()
 {
 	block_ = GPU_LoadShaderBlock(program_object_, "vertex", "texture_pos",
-								 "color", "model_view_proj");
+								 "draw_color", "model_view_proj");
 	GPU_ActivateShaderProgram(program_object_, &block_);
 }
 
@@ -92,5 +103,21 @@ void shader_program::deactivate()
 	}
 }
 
+void shader_program::set_color_mod(int r, int g, int b, int a)
+{
+	static float color_mod[4];
+	color_mod[0] = float(r) / 255;
+	color_mod[1] = float(g) / 255;
+	color_mod[2] = float(b) / 255;
+	color_mod[3] = float(a) / 255;
+
+	GPU_SetAttributefv(attr_color_mod_, 4, color_mod);
+}
+
+void shader_program::set_submerge(float val)
+{
+	GPU_SetAttributef(attr_submerge_, val);
+}
+
 }
 #endif
diff --git a/src/sdl/shader.hpp b/src/sdl/shader.hpp
index 8c63c97f482..aaec5ded58a 100644
--- a/src/sdl/shader.hpp
+++ b/src/sdl/shader.hpp
@@ -35,9 +35,13 @@ public:
 	void activate();
 	void deactivate();
 
+	void set_color_mod(int r, int g, int b, int a);
+	void set_submerge(float val);
+
 private:
 	Uint32 program_object_, vertex_object_, fragment_object_;
 	GPU_ShaderBlock block_;
+	int attr_color_mod_, attr_submerge_;
 	unsigned *refcount_;
 };