Allow zoom to actually show more data.

This allows the client to retrieve blocks at a greater distance
from the server, thus allowing for a real zoom.

src/camera.cpp

@@ -458,7 +458,7 @@ void Camera::update(LocalPlayer* player, f32 frametime, f32 busytime, f32 tool_r
 	} else {
 		fov_degrees = m_cache_fov;
 	}
-	fov_degrees = rangelim(fov_degrees, 7.0, 160.0);
+	fov_degrees = rangelim(fov_degrees, 1.0, 160.0);
 
 	// FOV and aspect ratio
 	const v2u32 &window_size = RenderingEngine::get_instance()->getWindowSize();
@@ -550,7 +550,8 @@ void Camera::updateViewingRange()
 {
 	f32 viewing_range = g_settings->getFloat("viewing_range");
 	f32 near_plane = g_settings->getFloat("near_plane");
-	m_draw_control.wanted_range = viewing_range;
+
+	m_draw_control.wanted_range = std::fmin(adjustDist(viewing_range, getFovMax()), 4000);
 	m_cameranode->setNearValue(rangelim(near_plane, 0.0f, 0.5f) * BS);
 	if (m_draw_control.range_all) {
 		m_cameranode->setFarValue(100000.0);

src/clientiface.cpp

@@ -196,6 +196,20 @@ void RemoteClient::GetNextBlocks (
 	s16 wanted_range = sao->getWantedRange() + 1;
 	float camera_fov = sao->getFov();
 
+	const s16 full_d_max = std::min(adjustDist(m_max_send_distance, camera_fov), wanted_range);
+	const s16 d_opt = std::min(adjustDist(m_block_optimize_distance, camera_fov), wanted_range);
+	const s16 d_blocks_in_sight = full_d_max * BS * MAP_BLOCKSIZE;
+	infostream << "Fov from client " << camera_fov << " full_d_max " << full_d_max << std::endl;
+
+	s16 d_max = full_d_max;
+	s16 d_max_gen = std::min(adjustDist(m_max_gen_distance, camera_fov), wanted_range);
+
+	// Don't loop very much at a time, adjust with distance,
+	// do more work per RTT with greater distances.
+	s16 max_d_increment_at_time = full_d_max / 9 + 1;
+	if (d_max > d_start + max_d_increment_at_time)
+		d_max = d_start + max_d_increment_at_time;
+
 	// cos(angle between velocity and camera) * |velocity|
 	// Limit to 0.0f in case player moves backwards.
 	f32 dot = rangelim(camera_dir.dotProduct(playerspeed), 0.0f, 300.0f);
@@ -204,19 +218,6 @@ void RemoteClient::GetNextBlocks (
 	// limit max fov effect to 50%, 60% at 20n/s fly speed
 	camera_fov = camera_fov / (1 + dot / 300.0f);
 
-	const s16 full_d_max = std::min(m_max_send_distance, wanted_range);
-	const s16 d_opt = std::min(m_block_optimize_distance, wanted_range);
-	const s16 d_blocks_in_sight = full_d_max * BS * MAP_BLOCKSIZE;
-	//infostream << "Fov from client " << camera_fov << " full_d_max " << full_d_max << std::endl;
-
-	s16 d_max = full_d_max;
-	s16 d_max_gen = std::min(m_max_gen_distance, wanted_range);
-
-	// Don't loop very much at a time
-	s16 max_d_increment_at_time = 2;
-	if (d_max > d_start + max_d_increment_at_time)
-		d_max = d_start + max_d_increment_at_time;
-
 	s32 nearest_emerged_d = -1;
 	s32 nearest_emergefull_d = -1;
 	s32 nearest_sent_d = -1;

src/util/numeric.cpp

@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "noise.h" // PseudoRandom, PcgRandom
 #include "threading/mutex_auto_lock.h"
 #include <cstring>
+#include <cmath>
 
 
 // myrand
@@ -161,3 +162,16 @@ bool isBlockInSight(v3s16 blockpos_b, v3f camera_pos, v3f camera_dir,
 
 	return true;
 }
+
+s16 adjustDist(s16 dist, float zoom_fov)
+{
+	// 1.775 ~= 72 * PI / 180 * 1.4, the default on the client
+	const float default_fov = 1.775f;
+	// heuristic cut-off for zooming
+	if (zoom_fov > default_fov / 2.0f)
+		return dist;
+
+	// new_dist = dist * ((1 - cos(FOV / 2)) / (1-cos(zoomFOV /2))) ^ (1/3)
+	return round(dist * cbrt((1.0f - cos(default_fov / 2.0f)) /
+		(1.0f - cos(zoom_fov / 2.0f))));
+}

src/util/numeric.h

@@ -232,6 +232,8 @@ u64 murmur_hash_64_ua(const void *key, int len, unsigned int seed);
 bool isBlockInSight(v3s16 blockpos_b, v3f camera_pos, v3f camera_dir,
 		f32 camera_fov, f32 range, f32 *distance_ptr=NULL);
 
+s16 adjustDist(s16 dist, float zoom_fov);
+
 /*
 	Returns nearest 32-bit integer for given floating point number.
 	<cmath> and <math.h> in VC++ don't provide round().