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Prt3 - Wow a triangle
Author: Ben_3D@xbdev.net
Finally something exciting - well if you understand it all up to now, you'll
be a game programmer in a few days. 3D is based on vertices, e.g. points
in space. X,Y,Z value represents were in space it is located. We
just join up these points to create complex shapes, like those used in Doom, or
Halo :)
A lot of the initialisation code is the same as before, you'll get used to it
in time, and eventually just put it in a separate file where you can call it
just once.
//Application entry point
void
__cdecl main()
{
InitialiseD3D();
while(true)
{
//Clear the backbuffer to black
g_pD3DDevice->Clear(0, NULL, D3DCLEAR_TARGET,
D3DCOLOR_XRGB(0, 255, 0), 1.0f, 0);
//Begin the scene
g_pD3DDevice->BeginScene();
//NEW NEW NEW NEW NEW NEW NEW NEW
NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW
DrawTriangle();
//End the scene
g_pD3DDevice->EndScene();
//Filp the back and front buffers so that whatever
has been rendered on the back buffer
//will now be visible on screen (front buffer).
g_pD3DDevice->Present(NULL, NULL, NULL, NULL);
}
CleanUp();
}
And next comes the DirectX Initilisation, and De-Initilisation.
//Main header file for the XDK
#include
<xtl.h>
LPDIRECT3D8
g_pD3D = NULL; // DirectX
Object
LPDIRECT3DDEVICE8 g_pD3DDevice = NULL; //
Screen Object
void
InitialiseD3D()
{
//First of all, create the main D3D object. If it is
created successfully we
//should get a pointer to an IDirect3D8 interface.
g_pD3D
= Direct3DCreate8(D3D_SDK_VERSION);
//Create a structure to hold the settings for our
device
D3DPRESENT_PARAMETERS d3dpp;
ZeroMemory(&d3dpp, sizeof(d3dpp));
//Fill the structure.
// Set fullscreen 640x480x32 mode
d3dpp.BackBufferWidth = 640;
d3dpp.BackBufferHeight = 480;
d3dpp.BackBufferFormat = D3DFMT_X8R8G8B8;
// Create one backbuffer
d3dpp.BackBufferCount = 1;
// Set up how the backbuffer is "presented" to the
frontbuffer each time
d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
//Create a Direct3D device.
g_pD3D->CreateDevice(0, D3DDEVTYPE_HAL, NULL,
D3DCREATE_HARDWARE_VERTEXPROCESSING,
&d3dpp, &g_pD3DDevice);
}
void
CleanUp()
{
g_pD3DDevice->Release();
g_pD3D->Release();
}
Finally the Code that draws our wonderful, wonderful triangle for us.
As you can see, the DrawTriangle code has to be called within the ->BeginScene(),
and ->EndScene()
member functions above in main(), I've commented the code with
//NEW NEW.. so that you can see the main points I am trying to outline.
//NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW
//NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW
LPDIRECT3DVERTEXBUFFER8 g_pVertexBuffer = NULL; //
Vertices Buffer
struct
CUSTOMVERTEX
{
FLOAT
x, y, z, rhw; // The transformed position for the vertex.
DWORD
colour; // The vertex colour.
};
#define
D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW|D3DFVF_DIFFUSE)
void
DrawTriangle()
{
VOID*
pVertices;
//Store each point of the triangle together with
it's colour
CUSTOMVERTEX cvVertices[] =
{
{250.0f, 100.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(255, 0, 0),},
//Vertex 1 - Red (250, 100)
{400.0f, 350.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 255, 0),},
//Vertex 2 - Green (400, 350)
{100.0f, 350.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 0, 255),},
//Vertex 3 - Blue (100, 350)
};
//Create the vertex buffer from our device
g_pD3DDevice->CreateVertexBuffer(3 * sizeof(CUSTOMVERTEX),
0,
D3DFVF_CUSTOMVERTEX,
D3DPOOL_DEFAULT,
&g_pVertexBuffer);
//Get a pointer to the vertex buffer vertices and
lock the vertex buffer
g_pVertexBuffer->Lock(0, sizeof(cvVertices),
(BYTE**)&pVertices, 0);
//Copy our stored vertices values into the vertex
buffer
memcpy(pVertices, cvVertices, sizeof(cvVertices));
//Unlock the vertex buffer
g_pVertexBuffer->Unlock();
//Rendering our triangle
g_pD3DDevice->SetStreamSource(0, g_pVertexBuffer,
sizeof(CUSTOMVERTEX));
g_pD3DDevice->SetVertexShader(D3DFVF_CUSTOMVERTEX);
g_pD3DDevice->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 1);
// Every time
we Create a vertex buffer, we must release one!.
g_pVertexBuffer->Release();
}
//NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW
//NEW
NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW
Yup, I can hear you say it from here, "Wow", a triangle, not just any
triangle, a funky coloured textured one on a blue background. Well when
you've just started out in the big bad world of xdk development I think it seems
pretty rewarding.
You can see from the DrawTriangle() function, that we set some vertices up
(e.g. x,y,z points) and just copy them into our directX buffer and render them
to the screen. DirectX buffer? Whats that? Well your graphics
card has memory onboard, and if we use the directX buffer it will put it in
there so that we can obtain better performance.
(Back Tutorials Page)
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