Support luminance formats as RGB.

OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme

@@ -73,12 +73,12 @@
             isEnabled = "NO">
          </CommandLineArgument>
          <CommandLineArgument
-            argument = "--new=zxspectrum"
+            argument = "--new=macintosh"
             isEnabled = "YES">
          </CommandLineArgument>
          <CommandLineArgument
             argument = "--display=CompositeColour"
-            isEnabled = "NO">
+            isEnabled = "YES">
          </CommandLineArgument>
          <CommandLineArgument
             argument = "/Users/thomasharte/Downloads/Program/Program.prg"

OSBindings/SDL/main.cpp

@@ -887,7 +887,6 @@ int main(int argc, char *argv[]) {
 
 	// Ask for no depth buffer but at least 1 bit of stencil.
 	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 0);
-	SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 1);
 	SDL_GL_SetSwapInterval(1);
 
 	SDL_Window *window = nullptr;

Outputs/OpenGL/Shaders/CompositionShader.cpp

@@ -128,6 +128,10 @@ lowp vec2 quadrature() {
 		);
 	}
 
+	lowp vec3 sample_rgb() {
+		return clamp(texture(source, coordinate).rrr * 255.0, vec3(0.0), vec3(1.0));
+	}
+
 #endif
 
 
@@ -144,6 +148,10 @@ lowp vec2 quadrature() {
 		);
 	}
 
+	lowp vec3 sample_rgb() {
+		return texture(source, coordinate).rrr;
+	}
+
 #endif