iOS : Need Control Over Background Overlay Alpha During Non-LiDAR Camera Scan

[gulam-luxolis]

Hello,

During a non-LiDAR scan, when the scanning starts, a background color overlay appears on the camera feed with some transparency (alpha value).

I’ve successfully set the background color as needed via the following method:

NativeWrapper > Scene.h > void setBackgroundColor(float r, float g, float b)

However, I haven't been able to locate the logic that controls the alpha (transparency) value of this overlay specifically for the non-LiDAR scan mode.

Could you please point me to where this alpha value is being set or managed? Any guidance would be greatly appreciated.

Thank you!

[matlabbe]

The gray color is created by this shader:

rtabmap/app/android/jni/background_renderer.cc

Lines 70 to 79 in 9650b71

	const std::string kFragmentShader =
	"precision mediump float;\n"
	"varying vec2 v_TexCoord;\n"
	"uniform sampler2D sTexture;\n"
	"uniform bool uRedUnknown;\n"
	"void main() {\n"
	" vec4 sample = texture2D(sTexture, v_TexCoord);\n"
	" float grey = 0.21 * sample.r + 0.71 * sample.g + 0.07 * sample.b;\n"
	" gl_FragColor = vec4(grey, uRedUnknown?0.0:grey, uRedUnknown?0.0:grey, 0.5);\n"
	"}\n";