§14.5挑战：编写自己的改编游戏

float4 PS_ComposeFinalImage20( VB_OutputPos3TexCoords In, uniform sampler2D sceneSampler, uniform sampler2D blurredSceneSampler) : COLOR

{

float4 orig = tex2D(sceneSampler, In.texCoord[0]);

float4 blur = tex2D(blurredSceneSampler, In.texCoord[1]);

float4 screenBorderFadeout = tex2D(screenBorderFadeoutMapSampler, In.texCoord[2]);

float4 ret = 0.75f*orig + GlowIntensity*blur+ HighlightIntensity*blur.a; ret.rgb *= screenBorderFadeout;

// Change colors a bit, sub 20% red and add 25% blue (photoshop values)

// Here the values are -4% and +5%

ret.rgb = float3( ret.r+0.054f/2, ret.g-0.021f/2, ret.b-0.035f/2);

// Change brightness -5% and contrast +10% r

et.rgb = ret.rgb * 0.975f;

ret.rgb = (ret.rgb - float3(0.5, 0.5, 0.5)) * 1.05f + float3(0.5, 0.5, 0.5);

return ret;

} // PS_ComposeFinalImage20(...)

/// <summary>

/// Minimun, maximum and default road width for our track.

/// </summary>

public const float MinRoadWidth = 0.25f,

DefaultRoadWidth = 1.0f, MaxRoadWidth = 2.0f, RoadWidthScale = 13.25f;

// [The constants are then used to generate the left and right track

// vertices ...]

/// <summary>

/// Left side track vertex generation, used for the GuardRail class.

/// </summary>

/// Track vertex

public TrackVertex LeftTrackVertex

{

get

{

return new TrackVertex( pos - RoadWidthScale * roadWidth * right / 2, right, up, dir, new Vector2(uv.X, 0), roadWidth);

} // get

} // LeftTrackVertex

// [etc.]

#region Constants

/// <summary>

/// Car is 1000 kg

/// </summary>

const float CarMass = 1000;//1000.0f;

/// <summary>

/// Gravity on earth is 9.81 m//// <summary>

/// Max speed of our car is 275 mph.

/// While we use mph for the display, we calculate internally with

/// meters per sec since meter is the unit we use for everthing in the

/// game. And it is a much nicer unit than miles or feet.

/// </summary>

public const float MaxSpeed = 275.0f * MphToMeterPerSec;

/// <summary>

/// Max. acceleration in m/s^2 we can do per second.

/// We have also to define the max and min overall acceleration we can

/// do with our car (very car specfic, but for this game always the same

/// to make it fair). Driving backwards is slower than driving forward.

/// </summary>

const float MaxAccelerationPerSec = 5.0f,//120.0f,//1000.0f,

MaxAcceleration = 10.0f,//70.0f,//250.0f,

MinAcceleration = -6.0f;//-35.0f;//250.0f;//-40.0f;

/// <summary>

/// Friction we have on the road each second. If we are driving slow,

/// this slows us down quickly. If we drive really fast, this does not

/// matter so much anymore. The main slowdown will be the air friction.

/// </summary>

const float CarFrictionOnRoad = 17.523456789f;//15.0f;//2.5f;

/// <summary>

/// Air friction we get if we drive fast, this slows us down very fast

/// if we drive fast. It makes it also much harder to drive faster if

/// we already drive at a very fast speed. For slow speeds the air

/// friction does not matter so much. This could be extended to include

/// wind and then even at low speeds the air friction would slow us

/// down or even influence our movement. Maybe in a game mod sometime.

/// </summary>

const float AirFrictionPerSpeed = 0.66f;//0.225f;//0.33f;//0.42f;

/// <summary>

/// Max air friction, this way we can have a good air friction for low

/// speeds but we are not limited to 190-210mph, but can drive faster.

/// </summary>

const float MaxAirFriction = AirFrictionPerSpeed * 200.0f;

/// <summary>

/// Break slowdown per second, 1.0 means we need 1 second to do a full

/// break. Slowdown is also limited by max. 100 per sec!

/// Note: This would not make sense in a real world simulation because

/// stopping the car usually needs more time and is highly dependant

/// on the speed resulting in longer stopping distances. For this game

/// it is easier and more fun to just always brake the same.

/// </summary>

const float BrakeSlowdown = 1.0f;

// [etc.]