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For clouds, use a RNG seed that only changes every 10 minutes.

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This allows multi-process deploymentes to keep their clouds in sync.
This commit is contained in:
Stuart Buchanan
2012-11-09 20:25:53 +00:00
parent 54778ee1e1
commit 279445d6bc
8 changed files with 49 additions and 20 deletions
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5
simgear/math/sg_random.c
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@@ -59,6 +59,11 @@ void mt_init(mt *mt, unsigned int seed)
mt->index = MT_N+1;
}
void mt_init_time_10(mt *mt)
{
mt_init(mt, (unsigned int) time(NULL) / 600);
}
unsigned int mt_rand32(mt *mt)
{
unsigned int i, y;

7
simgear/math/sg_random.h
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@@ -47,6 +47,13 @@ typedef struct {unsigned int array[MT_N]; int index; } mt;
*/
void mt_init(mt *mt, unsigned int seed);
/**
* Initialize a new MT state with a seed that only
* changes every 10 minutes. Used to synchronize
* multi-process deployments.
*/
void mt_init_time_10(mt *mt);
/**
* Generate a new 32-bit random number based on the given MT state.
*/

2
simgear/scene/sky/CloudShaderGeometry.hxx
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@@ -46,7 +46,7 @@ class CloudShaderGeometry : public osg::Drawable
const static unsigned int USR_ATTR_1 = 10;
const static unsigned int USR_ATTR_2 = 11;
const static unsigned int USR_ATTR_3 = 12;
const static unsigned int USR_ATTR_3 = 12;
CloudShaderGeometry()
{

5
simgear/scene/sky/cloud.cxx
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@@ -194,7 +194,10 @@ SGCloudLayer::SGCloudLayer( const string &tex_path ) :
->getWhiteTexture(),
osg::StateAttribute::ON);
rootSet->setDataVariance(osg::Object::DYNAMIC);
// Ensure repeatability of the random seed within 10 minutes,
// to keep multi-computer systems in sync.
sg_srandom_time_10();
base = osg::Vec2(sg_random(), sg_random());
group_top->addChild(layer_transform.get());
group_bottom->addChild(layer_transform.get());

33
simgear/scene/sky/newcloud.cxx
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@@ -40,7 +40,6 @@
#include <simgear/compiler.h>
#include <simgear/math/sg_random.h>
#include <simgear/misc/sg_path.hxx>
#include <simgear/props/props.hxx>
#include <simgear/scene/model/model.hxx>
@@ -73,6 +72,10 @@ float SGNewCloud::sprite_density = 1.0;
SGNewCloud::SGNewCloud(const SGPath &texture_root, const SGPropertyNode *cld_def)
{
// Set up a RNG that is repeatable within 10 minutes to ensure that clouds
// are synced up in multi-process deployments.
mt_init_time_10(&seed);
min_width = cld_def->getFloatValue("min-cloud-width-m", 500.0);
max_width = cld_def->getFloatValue("max-cloud-width-m", min_width*2);
min_height = cld_def->getFloatValue("min-cloud-height-m", 400.0);
@@ -132,7 +135,7 @@ SGNewCloud::~SGNewCloud() {
#if 0
// return a random number between -n/2 and n/2, tending to 0
static float Rnd(float n) {
return n * (-0.5f + (sg_random() + sg_random()) / 2.0f);
return n * (-0.5f + (mt_rand(&seed) + mt_rand(&seed)) / 2.0f);
}
#endif
@@ -143,17 +146,17 @@ osg::ref_ptr<EffectGeode> SGNewCloud::genCloud() {
// Determine how big this specific cloud instance is. Note that we subtract
// the sprite size because the width/height is used to define the limits of
// the center of the sprites, not their edges.
float width = min_width + sg_random() * (max_width - min_width) - min_sprite_width;
float height = min_height + sg_random() * (max_height - min_height) - min_sprite_height;
float width = min_width + mt_rand(&seed) * (max_width - min_width) - min_sprite_width;
float height = min_height + mt_rand(&seed) * (max_height - min_height) - min_sprite_height;
if (width < 0.0) { width = 0.0; }
if (height < 0.0) { height = 0.0; }
// Determine appropriate shading factors
float top_factor = min_top_lighting_factor + sg_random() * (max_top_lighting_factor - min_top_lighting_factor);
float middle_factor = min_middle_lighting_factor + sg_random() * (max_middle_lighting_factor - min_middle_lighting_factor);
float bottom_factor = min_bottom_lighting_factor + sg_random() * (max_bottom_lighting_factor - min_bottom_lighting_factor);
float shade_factor = min_shade_lighting_factor + sg_random() * (max_shade_lighting_factor - min_shade_lighting_factor);
float top_factor = min_top_lighting_factor + mt_rand(&seed) * (max_top_lighting_factor - min_top_lighting_factor);
float middle_factor = min_middle_lighting_factor + mt_rand(&seed) * (max_middle_lighting_factor - min_middle_lighting_factor);
float bottom_factor = min_bottom_lighting_factor + mt_rand(&seed) * (max_bottom_lighting_factor - min_bottom_lighting_factor);
float shade_factor = min_shade_lighting_factor + mt_rand(&seed) * (max_shade_lighting_factor - min_shade_lighting_factor);
//printf("Cloud: %2f, %2f, %2f, %2f\n", top_factor, middle_factor, bottom_factor, shade_factor);
@@ -173,7 +176,7 @@ osg::ref_ptr<EffectGeode> SGNewCloud::genCloud() {
float cull_distance_squared = min_sprite_height * min_sprite_height * 0.1f;
// The number of sprites we actually use is a function of the (user-controlled) density
int n_sprites = num_sprites * sprite_density * (0.5f + sg_random());
int n_sprites = num_sprites * sprite_density * (0.5f + mt_rand(&seed));
for (int i = 0; i < n_sprites; i++)
{
@@ -191,16 +194,16 @@ osg::ref_ptr<EffectGeode> SGNewCloud::genCloud() {
y = 0;
z = height * 0.5;
} else {
float theta = sg_random() * SGD_2PI;
float elev = sg_random() * SGD_PI;
float theta = mt_rand(&seed) * SGD_2PI;
float elev = mt_rand(&seed) * SGD_PI;
x = width * cos(theta) * 0.5f * sin(elev);
y = width * sin(theta) * 0.5f * sin(elev);
z = height * cos(elev) * 0.5f + height * 0.5f;
}
// Determine the height and width
float sprite_width = min_sprite_width + sg_random() * (max_sprite_width - min_sprite_width);
float sprite_height = min_sprite_height + sg_random() * (max_sprite_height - min_sprite_height);
float sprite_width = min_sprite_width + mt_rand(&seed) * (max_sprite_width - min_sprite_width);
float sprite_height = min_sprite_height + mt_rand(&seed) * (max_sprite_height - min_sprite_height);
// Sprites are never taller than square.
if (sprite_height > sprite_width )
@@ -223,10 +226,10 @@ osg::ref_ptr<EffectGeode> SGNewCloud::genCloud() {
}
// Determine the sprite texture indexes.
int index_x = (int) floor(sg_random() * num_textures_x);
int index_x = (int) floor(mt_rand(&seed) * num_textures_x);
if (index_x >= num_textures_x) { index_x = num_textures_x - 1; }
int index_y = (int) floor(sg_random() * num_textures_y);
int index_y = (int) floor(mt_rand(&seed) * num_textures_y);
if (height_map_texture) {
// The y index depends on the position of the sprite within the cloud.

4
simgear/scene/sky/newcloud.hxx
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@@ -28,6 +28,7 @@
#include <vector>
#include <osg/Fog>
#include <simgear/math/sg_random.h>
#include <simgear/scene/material/Effect.hxx>
#include <simgear/scene/material/EffectGeode.hxx>
@@ -100,6 +101,9 @@ private:
osg::Geometry* quad;
osg::ref_ptr<simgear::Effect> effect;
static float sprite_density;
// RNG seed for this cloud
mt seed;
osg::Geometry* createOrthQuad(float w, float h, int varieties_x, int varieties_y);
};

9
simgear/scene/sky/sky.cxx
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@@ -29,7 +29,6 @@
#include "cloudfield.hxx"
#include "newcloud.hxx"
#include <simgear/math/sg_random.h>
#include <simgear/scene/util/RenderConstants.hxx>
#include <simgear/scene/util/OsgMath.hxx>
#include <simgear/sg_inlines.h>
@@ -68,6 +67,10 @@ SGSky::SGSky( void ) {
pre_transform = new osg::Group;
_ephTransform = new osg::MatrixTransform;
// Set up a RNG that is repeatable within 10 minutes to ensure that clouds
// are synced up in multi-process deployments.
mt_init_time_10(&seed);
}
@@ -373,11 +376,11 @@ void SGSky::modify_vis( float alt, float time_factor ) {
if ( ratio < 1.0 ) {
if ( ! in_puff ) {
// calc chance of entering cloud puff
double rnd = sg_random();
double rnd = mt_rand(&seed);
double chance = rnd * rnd * rnd;
if ( chance > 0.95 /* * (diff - 25) / 50.0 */ ) {
in_puff = true;
puff_length = sg_random() * 2.0; // up to 2 seconds
puff_length = mt_rand(&seed) * 2.0; // up to 2 seconds
puff_progression = 0.0;
}
}

4
simgear/scene/sky/sky.hxx
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@@ -34,6 +34,7 @@
#endif
#include <simgear/compiler.h>
#include <simgear/math/sg_random.h>
#include <simgear/misc/sg_path.hxx>
#include <simgear/props/props.hxx>
@@ -250,6 +251,9 @@ private:
// 3D cloud density
double clouds_3d_density;
// RNG seed
mt seed;
public: