From 71e94ee161447b84c0eaabf6567f8fa62262cd3e Mon Sep 17 00:00:00 2001 From: Mirrorbot Date: Sat, 27 Dec 2025 17:53:06 -0600 Subject: Inital commit --- examples/23.SMeshHandling/tutorial.html | 209 ++++++++++++++++++++++++++++++++ 1 file changed, 209 insertions(+) create mode 100644 examples/23.SMeshHandling/tutorial.html (limited to 'examples/23.SMeshHandling/tutorial.html') diff --git a/examples/23.SMeshHandling/tutorial.html b/examples/23.SMeshHandling/tutorial.html new file mode 100644 index 0000000..b5ef8e8 --- /dev/null +++ b/examples/23.SMeshHandling/tutorial.html @@ -0,0 +1,209 @@ + + + + + + + +Tutorial 23: SMeshBufferHandling + + + + +
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Tutorial 23: SMeshBufferHandling
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A tutorial by geoff.

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In this tutorial we'll learn how to create custom meshes and deal with them with Irrlicht. We'll create an interesting heightmap with some lighting effects. With keys 1,2,3 you can choose a different mesh layout, which is put into the mesh buffers as desired. All positions, normals, etc. are updated accordingly.

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Ok, let's start with the headers (I think there's nothing to say about it)

#include <irrlicht.h>
#include "driverChoice.h"
#ifdef _MSC_VER
#pragma comment(lib, "Irrlicht.lib")
#endif
//Namespaces for the engine
using namespace irr;
using namespace video;
using namespace core;
using namespace scene;
using namespace io;
using namespace gui;

This is the type of the functions which work out the colour.

typedef SColor colour_func(f32 x, f32 y, f32 z);

Here comes a set of functions which can be used for coloring the nodes while creating the mesh.

// Greyscale, based on the height.
SColor grey(f32, f32, f32 z)
{
u32 n = (u32)(255.f * z);
return SColor(255, n, n, n);
}
// Interpolation between blue and white, with red added in one
// direction and green in the other.
SColor yellow(f32 x, f32 y, f32)
{
return SColor(255, 128 + (u32)(127.f * x), 128 + (u32)(127.f * y), 255);
}
// Pure white.
SColor white(f32, f32, f32) { return SColor(255, 255, 255, 255); }

The type of the functions which generate the heightmap. x and y range between -0.5 and 0.5, and s is the scale of the heightmap.

typedef f32 generate_func(s16 x, s16 y, f32 s);
// An interesting sample function :-)
f32 eggbox(s16 x, s16 y, f32 s)
{
const f32 r = 4.f*sqrtf((f32)(x*x + y*y))/s;
const f32 z = expf(-r * 2) * (cosf(0.2f * x) + cosf(0.2f * y));
return 0.25f+0.25f*z;
}
// A rather dumb sine function :-/
f32 moresine(s16 x, s16 y, f32 s)
{
const f32 xx=0.3f*(f32)x/s;
const f32 yy=12*y/s;
const f32 z = sinf(xx*xx+yy)*sinf(xx+yy*yy);
return 0.25f + 0.25f * z;
}
// A simple function
f32 justexp(s16 x, s16 y, f32 s)
{
const f32 xx=6*x/s;
const f32 yy=6*y/s;
const f32 z = (xx*xx+yy*yy);
return 0.3f*z*cosf(xx*yy);
}

A simple class for representing heightmaps. Most of this should be obvious.

class HeightMap
{
private:
const u16 Width;
const u16 Height;
f32 s;
core::array<f32> data;
public:
HeightMap(u16 _w, u16 _h) : Width(_w), Height(_h), s(0.f), data(0)
{
s = sqrtf((f32)(Width * Width + Height * Height));
data.set_used(Width * Height);
}
// Fill the heightmap with values generated from f.
void generate(generate_func f)
{
u32 i=0;
for(u16 y = 0; y < Height; ++y)
for(u16 x = 0; x < Width; ++x)
set(i++, calc(f, x, y));
}
u16 height() const { return Height; }
u16 width() const { return Width; }
f32 calc(generate_func f, u16 x, u16 y) const
{
const f32 xx = (f32)x - Width*0.5f;
const f32 yy = (f32)y - Height*0.5f;
return f((u16)xx, (u16)yy, s);
}
// The height at (x, y) is at position y * Width + x.
void set(u16 x, u16 y, f32 z) { data[y * Width + x] = z; }
void set(u32 i, f32 z) { data[i] = z; }
f32 get(u16 x, u16 y) const { return data[y * Width + x]; }

The only difficult part. This considers the normal at (x, y) to be the cross product of the vectors between the adjacent points in the horizontal and vertical directions.

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s is a scaling factor, which is necessary if the height units are different from the coordinate units; for example, if your map has heights in metres and the coordinates are in units of a kilometer.

vector3df getnormal(u16 x, u16 y, f32 s) const
{
const f32 zc = get(x, y);
f32 zl, zr, zu, zd;
if (x == 0)
{
zr = get(x + 1, y);
zl = zc + zc - zr;
}
else if (x == Width - 1)
{
zl = get(x - 1, y);
zr = zc + zc - zl;
}
else
{
zr = get(x + 1, y);
zl = get(x - 1, y);
}
if (y == 0)
{
zd = get(x, y + 1);
zu = zc + zc - zd;
}
else if (y == Height - 1)
{
zu = get(x, y - 1);
zd = zc + zc - zu;
}
else
{
zd = get(x, y + 1);
zu = get(x, y - 1);
}
return vector3df(s * 2 * (zl - zr), 4, s * 2 * (zd - zu)).normalize();
}
};

A class which generates a mesh from a heightmap.

class TMesh
{
private:
u16 Width;
u16 Height;
f32 Scale;
public:
SMesh* Mesh;
TMesh() : Mesh(0), Width(0), Height(0), Scale(1.f)
{
Mesh = new SMesh();
}
~TMesh()
{
Mesh->drop();
}
// Unless the heightmap is small, it won't all fit into a single
// SMeshBuffer. This function chops it into pieces and generates a
// buffer from each one.
void init(const HeightMap &hm, f32 scale, colour_func cf, IVideoDriver *driver)
{
Scale = scale;
const u32 mp = driver -> getMaximalPrimitiveCount();
Width = hm.width();
Height = hm.height();
const u32 sw = mp / (6 * Height); // the width of each piece
u32 i=0;
for(u32 y0 = 0; y0 < Height; y0 += sw)
{
u16 y1 = y0 + sw;
if (y1 >= Height)
y1 = Height - 1; // the last one might be narrower
addstrip(hm, cf, y0, y1, i);
++i;
}
if (i<Mesh->getMeshBufferCount())
{
// clear the rest
for (u32 j=i; j<Mesh->getMeshBufferCount(); ++j)
{
Mesh->getMeshBuffer(j)->drop();
}
Mesh->MeshBuffers.erase(i,Mesh->getMeshBufferCount()-i);
}
// set dirty flag to make sure that hardware copies of this
// buffer are also updated, see IMesh::setHardwareMappingHint
Mesh->setDirty();
Mesh->recalculateBoundingBox();
}
// Generate a SMeshBuffer which represents all the vertices and
// indices for values of y between y0 and y1, and add it to the
// mesh.
void addstrip(const HeightMap &hm, colour_func cf, u16 y0, u16 y1, u32 bufNum)
{
SMeshBuffer *buf = 0;
if (bufNum<Mesh->getMeshBufferCount())
{
buf = (SMeshBuffer*)Mesh->getMeshBuffer(bufNum);
}
else
{
// create new buffer
buf = new SMeshBuffer();
Mesh->addMeshBuffer(buf);
// to simplify things we drop here but continue using buf
buf->drop();
}
buf->Vertices.set_used((1 + y1 - y0) * Width);
u32 i=0;
for (u16 y = y0; y <= y1; ++y)
{
for (u16 x = 0; x < Width; ++x)
{
const f32 z = hm.get(x, y);
const f32 xx = (f32)x/(f32)Width;
const f32 yy = (f32)y/(f32)Height;
S3DVertex& v = buf->Vertices[i++];
v.Pos.set(x, Scale * z, y);
v.Normal.set(hm.getnormal(x, y, Scale));
v.Color=cf(xx, yy, z);
v.TCoords.set(xx, yy);
}
}
buf->Indices.set_used(6 * (Width - 1) * (y1 - y0));
i=0;
for(u16 y = y0; y < y1; ++y)
{
for(u16 x = 0; x < Width - 1; ++x)
{
const u16 n = (y-y0) * Width + x;
buf->Indices[i]=n;
buf->Indices[++i]=n + Width;
buf->Indices[++i]=n + Width + 1;
buf->Indices[++i]=n + Width + 1;
buf->Indices[++i]=n + 1;
buf->Indices[++i]=n;
++i;
}
}
buf->recalculateBoundingBox();
}
};

Our event receiver implementation, taken from tutorial 4.

class MyEventReceiver : public IEventReceiver
{
public:
// This is the one method that we have to implement
virtual bool OnEvent(const SEvent& event)
{
// Remember whether each key is down or up
if (event.EventType == irr::EET_KEY_INPUT_EVENT)
KeyIsDown[event.KeyInput.Key] = event.KeyInput.PressedDown;
return false;
}
// This is used to check whether a key is being held down
virtual bool IsKeyDown(EKEY_CODE keyCode) const
{
return KeyIsDown[keyCode];
}
MyEventReceiver()
{
for (u32 i=0; i<KEY_KEY_CODES_COUNT; ++i)
KeyIsDown[i] = false;
}
private:
// We use this array to store the current state of each key
bool KeyIsDown[KEY_KEY_CODES_COUNT];
};

Much of this is code taken from some of the examples. We merely set up a mesh from a heightmap, light it with a moving light, and allow the user to navigate around it.

int main(int argc, char* argv[])
{
// ask user for driver
video::E_DRIVER_TYPE driverType=driverChoiceConsole();
if (driverType==video::EDT_COUNT)
return 1;
MyEventReceiver receiver;
IrrlichtDevice* device = createDevice(driverType,
core::dimension2du(800, 600), 32, false, false, false,
&receiver);
if(device == 0)
return 1;
IVideoDriver *driver = device->getVideoDriver();
ISceneManager *smgr = device->getSceneManager();
device->setWindowCaption(L"Irrlicht Example for SMesh usage.");

Create the custom mesh and initialize with a heightmap

TMesh mesh;
HeightMap hm = HeightMap(255, 255);
hm.generate(eggbox);
mesh.init(hm, 50.f, grey, driver);
// Add the mesh to the scene graph
IMeshSceneNode* meshnode = smgr -> addMeshSceneNode(mesh.Mesh);
meshnode->setMaterialFlag(video::EMF_BACK_FACE_CULLING, false);
// light is just for nice effects
ILightSceneNode *node = smgr->addLightSceneNode(0, vector3df(0,100,0),
SColorf(1.0f, 0.6f, 0.7f, 1.0f), 500.0f);
if (node)
{
node->getLightData().Attenuation.set(0.f, 1.f/500.f, 0.f);
ISceneNodeAnimator* anim = smgr->createFlyCircleAnimator(vector3df(0,150,0),250.0f);
if (anim)
{
node->addAnimator(anim);
anim->drop();
}
}
ICameraSceneNode* camera = smgr->addCameraSceneNodeFPS();
if (camera)
{
camera->setPosition(vector3df(-20.f, 150.f, -20.f));
camera->setTarget(vector3df(200.f, -80.f, 150.f));
camera->setFarValue(20000.0f);
}

Just a usual render loop with event handling. The custom mesh is a usual part of the scene graph which gets rendered by drawAll.

while(device->run())
{
if(!device->isWindowActive())
{
device->sleep(100);
continue;
}
if(receiver.IsKeyDown(irr::KEY_KEY_W))
{
meshnode->setMaterialFlag(video::EMF_WIREFRAME, !meshnode->getMaterial(0).Wireframe);
}
else if(receiver.IsKeyDown(irr::KEY_KEY_1))
{
hm.generate(eggbox);
mesh.init(hm, 50.f, grey, driver);
}
else if(receiver.IsKeyDown(irr::KEY_KEY_2))
{
hm.generate(moresine);
mesh.init(hm, 50.f, yellow, driver);
}
else if(receiver.IsKeyDown(irr::KEY_KEY_3))
{
hm.generate(justexp);
mesh.init(hm, 50.f, yellow, driver);
}
driver->beginScene(true, true, SColor(0xff000000));
smgr->drawAll();
driver->endScene();
}
device->drop();
return 0;
}

That's it! Just compile and play around with the program.

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