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我是着色器編程的新手，只是對下面的代碼感到迷惑，它將「noiseCoord.xy」除以5，這是一個很大的分母，儘管我知道noiseCoord的範圍通常在0.0到1.0之間，但實際上我有這麼多的情況，除以一個很大的分母，它是否具有實驗價值？謝謝你在先進的！爲什麼與一個綁定到「TEXCOORD0」語義的變量相關的着色器代碼片段除以5
//Vertex program
void main_vp_old(
float4 pos : POSITION,
float4 normal : NORMAL,
float2 tex : TEXCOORD0,
out float4 oPos : POSITION,
out float fresnel : COLOR,
out float3 noiseCoord : TEXCOORD0,
out float4 projectionCoord : TEXCOORD1,
uniform float4x4 worldViewProjMatrix,
uniform float3 eyePosition, // object space
uniform float fresnelBias,
uniform float fresnelScale,
uniform float fresnelPower,
uniform float timeVal,
uniform float scale, // the amount to scale the noise texture by
uniform float scroll, // the amount by which to scroll the noise
uniform float noise // the noise perturb as a factor of the time
)
{
oPos = mul(worldViewProjMatrix, pos);
..........................................
..........................................
// Noise map coords
noiseCoord.xy = (tex + (timeVal * scroll)) * scale;
noiseCoord.z = noise * timeVal;
..........................................
}
// Fragment program for distorting a texture using a 3D noise texture
void main_fp(
float3 noiseCoord : TEXCOORD0,
float4 projectionCoord : TEXCOORD1,
float3 eyeDir : TEXCOORD2,
float3 normal : TEXCOORD3,
out float4 col : COLOR,
uniform float4 tintColour,
uniform float noiseScale,
uniform float fresnelBias,
uniform float fresnelScale,
uniform float fresnelPower,
uniform sampler2D noiseMap : register(s0),
uniform sampler2D reflectMap : register(s1),
uniform sampler2D refractMap : register(s2)
)
{
// Do the tex projection manually so we can distort _after_
float2 final = projectionCoord.xy/projectionCoord.w;
// just here, why was divided by such 5 instead of others?
float3 noiseNormal = (tex2D(noiseMap, (noiseCoord.xy/5)).rgb - 0.5).rbg * noiseScale;
final += noiseNormal.xz;
// Fresnel
//normal = normalize(normal + noiseNormal.xz);
float fresnel = fresnelBias + fresnelScale * pow(1 + dot(eyeDir, normal), fresnelPower);
// Reflection/refraction
float4 reflectionColour = tex2D(reflectMap, final);
float4 refractionColour = tex2D(refractMap, final) + tintColour;
// Final colour
col = lerp(refractionColour, reflectionColour, fresnel);
}