Section 3 - Getting D3D to Work

8/14/2019 Section 3 - Getting D3D to Work

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Computer GraphicsComputer Graphics

Using Direct 3DUsing Direct 3D

Getting D3D to WorkGetting D3D to Work


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Outline Review on D3D Pipeline

D3D H/W Interface (D3D Devices)

COM Objects Direct3D Initialization

Some Issues Swap Chain

Depth Buffer

Multisampling


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Outline Review on D3D Pipeline D3D H/W Interface (D3D Devices)


Some Issues

Swap Chain Depth Buffer

Multisampling


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Review on D3D Pipeline


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D3D Devices

Image from [MSDN]


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D3D Devices

D3D executes graphics operations via a device.

A HAL(Hardware Abstraction Layer) deviceisa set of device-specific code that instructs thegraphics hardware device to perform graphicsoperations needed by Direct3D. It isimplemented by the manufacturer of thegraphics hardware, making D3D device

independent.


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D3D Devices (Cont.)

A device may not implement allfeatures exposed by Direct3D in the

HAL. You must check the device capabilities

for graphics features before using

them.


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D3D Devices (Cont.)

The REFdevice is a special device provided byDirect3D that emulates graphics operations insoftware. It can be used for testing and

debugging purposes but is not appropriate forordinary usage.


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Component Object Model

Direct3D follows Component Object Model (COM)

All classes (called interfaces) are derived fromIUknown

COM objects perform their own memory management To create an object, use a create function (not new).

When done, use IUknown::Release (not delete)

All interfaces have their names prefixed with I


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Outline Review on D3D Pipeline D3D H/W Interface (D3D Devices)


Some Issues

Swap Chain Depth Buffer

Multisampling


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D3D Initialization

D3D Initialization Steps Obtaining an IDirect3D9 interface

Checking the hardware capabilities Filling out the presentation parameters Creating the device


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D3D Initialization (Cont.)

Step 1 : Obtaining Idirect3D9

IDirect3D9* _d3d9; _d3d9 = Direct3DCreate9(

D3D_SDK_VERSION);


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Step 2 : Checking the HW CapabilitiesD3DCAPS9 caps;

d3d9->GetDeviceCaps(D3DADAPTER_DEFAULT,

D3DDEVTYPE_HAL, &caps);

//Example: Transform & Lighting

if(caps.DevCaps &D3DDEVCAPS_HWTRANSFORMANDLIGHT )

{ //HW Vertex Processing is Supported }


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Step 3 : Initializing PresentationParameters

D3DPRESENT_PARAMETERS d3dpp;

d3dpp.BackBufferWidth=800; d3dpp.BackBufferHeight=600;

d3dpp.BackBufferFormat = D3DFMT_A8R8G8B8; //pixel format

d3dpp.BackBufferCount = 1;

d3dpp.MultiSampleType = D3DMULTISAMPLE_NONE;

d3dpp.MultiSampleQuality = 0;

d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;

d3dpp.hDeviceWindow = hwnd;

d3dpp.Windowed = false; // fullscreen


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Step 3 : Initializing PresentationParameters

d3dpp.EnableAutoDepthStencil = true;

d3dpp.AutoDepthStencilFormat = D3DFMT_D24S8;

d3dpp.Flags = 0;

d3dpp.FullScreen_RefreshRateInHz =D3DPRESENT_RATE_DEFAULT;

d3dpp.PresentationInterval =D3DPRESENT_INTERVAL_IMMEDIATE;


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Step 4 : Creating DeviceIDirect3DDevice9* device = 0;

hr = d3d9->CreateDevice(

D3DADAPTER_DEFAULT, // primary adapter

D3DDEVTYPE_HAL, // device type

hwnd, // window associated with device

D3DCREATE_HARDWARE_VERTEXPROCESSING, // vertexprocessing type

&d3dpp, // present parameters

&device); // returned created device

if( FAILED(hr) )

{ //Handle hailure here

return 0;

}


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Swap Chain

To provide smooth (flicker-free)animation between frames, Direct3D

maintains multiple rendering surfaces(2 or 3)


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Swap Chain (Cont.)

A back buffer ispresentedby

being promotedas a frontbuffer.


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Depth Buffer

It is a buffer of the same size of theimage (one entry per pixel).

Contains the depth valuecorresponding each rendered pixel.

Used to test whether the pixel is

hidden by another object (depth-test).


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Multisampling

One of the problems in graphics is thealiasing artifact, which results in the

appearance of jagged edges thatshould be straight.


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Multisampling (Cont.)

Multisampling is a technique for full-screen anti-aliasing (FSAA).

Conceptually, it is achieved by rendering the scene

to a higher resolution image and then sampling eachpixel in the final image from the correspondingpixels in the higher resolution image.


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Summary

Direct3D uses a device to access HW.

Direct3D provides HAL device and

REF device (for SW emulation). Direct3D follows COM model.


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Summary (Cont.)

To initialize D3D we Obtain IDirect3D9 interface

Check HW capabilities Fill presentation parameters

Create device


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Summary (Cont.)

A swap chain of multiple buffers isused for smooth animation.

A depth buffer is used to test forocclusion.

Multisampling is used for full-screen

anti-aliasing to provide smooth edges.


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Any Questions ??


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Surfaces (Optional

Reading) A surface is a matrix of pixels used tostore 2D image data.


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Surfaces (Cont.)

To process a surface Use LockRect to obtain a D3DLOCKED_RECT pointer.

It allows you to access the pixel array and get the

pitch (in bytes). Use GetDesc to get surface description. It allows

you to get information such as width and height (inpixels).

Use pointer arithmetic to access pixels. Call UnlockRect to unlock surface memory.

Section 3 - Getting D3D to Work

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