Allow tuning bicubic sharpness

mkxp.json

@@ -88,6 +88,14 @@
     // "smoothScaling": 0,
 
 
+    // Sharpness when using Bicubic scaling.
+    // A good starting range is 0 to 100,
+    // but you may wish to go outside that range in either direction.
+    // (default: 100)
+    //
+    // "bicubicSharpness": 100,
+
+
     // Replace the game's Bitmap files with external high-res files
     // provided in the "Hires" directory.
     // (You'll also need to set the below Scaling Factors.)

src/config.cpp

@@ -135,6 +135,7 @@ void Config::read(int argc, char *argv[]) {
         {"fullscreen", false},
         {"fixedAspectRatio", true},
         {"smoothScaling", 0},
+        {"bicubicSharpness", 100},
         {"enableHires", false},
         {"textureScalingFactor", 1.},
         {"framebufferScalingFactor", 1.},
@@ -263,6 +264,7 @@ try { exp } catch (...) {}
     SET_OPT(fullscreen, boolean);
     SET_OPT(fixedAspectRatio, boolean);
     SET_OPT(smoothScaling, integer);
+    SET_OPT(bicubicSharpness, integer);
     SET_OPT(enableHires, boolean);
     SET_OPT(textureScalingFactor, number);
     SET_OPT(framebufferScalingFactor, number);

src/config.h

@@ -44,6 +44,7 @@ struct Config {
     bool fullscreen;
     bool fixedAspectRatio;
     int smoothScaling;
+    int bicubicSharpness;
     bool enableHires;
     double textureScalingFactor;
     double framebufferScalingFactor;

src/display/gl/gl-meta.cpp

@@ -161,6 +161,7 @@ static void _blitBegin(FBO::ID fbo, const Vec2i &size)
 			shader.applyViewportProj();
 			shader.setTranslation(Vec2i());
 			shader.setTexSize(Vec2i(size.x, size.y));
+			shader.setSharpness(shState->config().bicubicSharpness);
 		}
 
 			break;

src/display/gl/shader.cpp

@@ -777,9 +777,11 @@ BicubicShader::BicubicShader()
 	GET_U(texOffsetX);
 	GET_U(sourceSize);
 	GET_U(bc);
+}
 
-	// TODO: Maybe expose this as a setting?
-	gl.Uniform2f(u_bc, 0.0, 0.5);
+void BicubicShader::setSharpness(int sharpness)
+{
+	gl.Uniform2f(u_bc, 1.f - sharpness * 0.01f, sharpness * 0.005f);
 }
 
 Lanczos3Shader::Lanczos3Shader()

src/display/gl/shader.h

@@ -346,6 +346,8 @@ class BicubicShader : public Lanczos3Shader
 public:
 	BicubicShader();
 
+	void setSharpness(int sharpness);
+
 protected:
 	GLint u_bc;
 };