highlight colliding drones

shaders/main.frag

@@ -3,6 +3,7 @@ varying vec2 uv;
 varying vec3 frag_pos;
 
 uniform sampler2D tex;
+uniform bool highlight;
 
 void main() {
 	vec3 light_col = vec3(1, .964, .783);
@@ -12,5 +13,10 @@ void main() {
 	float diff = max(dot(normalize(norm), light_dir), 0.0);
 	vec3 diffuse = diff * light_col;
 
-	gl_FragColor = texture2D(tex, uv) * vec4(ambient + diffuse, 1);
+	vec4 col = texture2D(tex, uv) * vec4(ambient + diffuse, 1);
+
+	if (highlight) {
+		col = mix(col, vec4(1, 0, 0, 1), .5);
+	}
+	gl_FragColor = col;
 }

src/drone_controller.cc

@@ -45,14 +45,21 @@ DroneController::DroneController(const QJsonObject &json)
 
 
 void DroneController::draw(QOpenGLExtraFunctions *f) const {
+	const QVector<QPair<int, int>> &col = collisions[frame];
 	for (const Drone &d : drones) {
 		QMatrix4x4 mat;
 		mat.translate(d.getPos());
+		for (const QPair<int, int> &p : col) {
+			if (d.getId() == p.first || d.getId() == p.second) {
+				OpenGLWidget::instance->getMainProgram()->setUniformValue("highlight", true);
+			}
+		}
 		d.getMesh()->draw(f, mat);
 		if (draw_spheres) {
 			mat.scale(sphere_radius);
 			sphere->draw(f, mat);
 		}
+		OpenGLWidget::instance->getMainProgram()->setUniformValue("highlight", false);
 	}
 }
 
@@ -116,6 +123,7 @@ void DroneController::seek(int frame) {
 
 
 void DroneController::computeCollisions(double sphere_radius) {
+	collisions.clear();
 	double sqDist = sphere_radius * sphere_radius * 4;
 	for (int i = 0; i < duration; i++) {
 		for (Drone &a : drones) {
@@ -124,6 +132,7 @@ void DroneController::computeCollisions(double sphere_radius) {
 				b.setTo(i);
 				if (&a == &b) continue;
 				if (collides(a, b, sqDist)) {
+					collisions[i].append(QPair<int, int>(a.getId(), b.getId()));
 					emit collision(a.getId(), b.getId(), i);
 				}
 			}

src/drone_controller.hh

@@ -22,6 +22,7 @@ class DroneController : public QObject, public Painter {
 	bool draw_spheres = false;
 	double sphere_radius = 0;
 	QTimer sphere_timer;
+	QMap<int, QVector<QPair<int, int>>> collisions;
 
 	static OpenGLMesh *sphere;
 	static const unsigned char sphere_neutral[];

src/opengl_widget.cc

@@ -186,6 +186,7 @@ void OpenGLWidget::paintGL() {
 	main_program.bind();
 	main_program.setUniformValue("proj", proj);
 	main_program.setUniformValue("view", view);
+	main_program.setUniformValue("highlight", false);
 	glActiveTexture(GL_TEXTURE0);
 	ground->draw(this, QMatrix4x4());
 	if (painter) painter->draw(this);