actually use the OFFSCREEN constant

modules/v4d/samples/beauty-demo.cpp

@@ -333,7 +333,7 @@ int main(int argc, char **argv) {
 int main() {
 #endif
     using namespace cv::v4d;
-    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Beautification Demo", false, false, 0);
+    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Beautification Demo", OFFSCREEN, false, 0);
     window->printSystemInfo();
 
     facemark->loadModel("assets/models/lbfmodel.yaml");

modules/v4d/samples/cube-demo.cpp

@@ -241,7 +241,7 @@ static bool iteration(cv::Ptr<V4D> window) {
 }
 
 int main() {
-    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Cube Demo", false, false, 0);
+    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Cube Demo", OFFSCREEN, false, 0);
     window->printSystemInfo();
 #ifndef __EMSCRIPTEN__
     //Creates a writer sink (which might be hardware accelerated)

modules/v4d/samples/many_cubes-demo.cpp

@@ -254,7 +254,7 @@ static bool iteration(cv::Ptr<V4D> window) {
 }
 
 int main() {
-    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Many Cubes Demo", false, false, 0);
+    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Many Cubes Demo", OFFSCREEN, false, 0);
     window->printSystemInfo();
 
 #ifndef __EMSCRIPTEN__

modules/v4d/samples/nanovg-demo.cpp

@@ -182,7 +182,7 @@ int main(int argc, char **argv) {
 #else
 int main() {
 #endif
-    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Mandelbrot Shader Demo", false, false, 0);
+    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Mandelbrot Shader Demo", OFFSCREEN, false, 0);
     window->printSystemInfo();
 
 #ifndef __EMSCRIPTEN__

modules/v4d/samples/optflow-demo.cpp

@@ -479,9 +479,9 @@ int main(int argc, char **argv) {
 
     try {
         using namespace cv::v4d;
-        cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Sparse Optical Flow Demo", false, false, 0);
+        cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Sparse Optical Flow Demo", OFFSCREEN, false, 0);
 #ifndef __EMSCRIPTEN__
-        miniWindow = V4D::make(270, 240, "Mini", false, false, 0);
+        miniWindow = V4D::make(270, 240, "Mini", OFFSCREEN, false, 0);
 #endif
         window->printSystemInfo();
         window->setStretching(stretch);

modules/v4d/samples/pedestrian-demo.cpp

@@ -235,7 +235,7 @@ int main(int argc, char **argv) {
 int main() {
 #endif
     using namespace cv::v4d;
-    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Pedestrian Demo", false, false, 0);
+    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Pedestrian Demo", OFFSCREEN, false, 0);
     hog.setSVMDetector(cv::HOGDescriptor::getDefaultPeopleDetector());
 
     window->printSystemInfo();

modules/v4d/samples/shader-demo.cpp

@@ -26,8 +26,6 @@ constexpr const char* OUTPUT_FILENAME = "shader-demo.mkv";
 int glow_kernel_size = std::max(int(DIAG / 200 % 2 == 0 ? DIAG / 200 + 1 : DIAG / 200), 1);
 // Red, green, blue and alpha. All from 0.0f to 1.0f
 float base_color_val[4] = {0.2, 0.6, 1.0, 1.0};
-// Keep alpha separate for the GUI
-float alpha = 1.0f; //0.0-1.0
 //contrast boost
 int contrast_boost = 15; //0.0-255
 //max fractal iterations

modules/v4d/samples/video-demo.cpp

@@ -218,7 +218,7 @@ int main(int argc, char** argv) {
 int main() {
 #endif
     using namespace cv::v4d;
-    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Video Demo", false, false, 0);
+    cv::Ptr<V4D> window = V4D::make(WIDTH, HEIGHT, "Video Demo", OFFSCREEN, false, 0);
     window->printSystemInfo();
 
 #ifndef __EMSCRIPTEN__