   Cg fragment program arrays
  I'm having some trouble getting the following Cg fragment program to compile:struct Input {float3 position: TEXCOORD0;float3 normal: TEXCOORD1;float2 texCoord: TEXCOORD2;float3 tangent: TEXCOORD3;float3 binormal: TEXCOORD4;};// texturesuniform sampler2D diffuseMap: TEXUNIT0;uniform sampler2D specularMap: TEXUNIT1;uniform sampler2D bumpMap: TEXUNIT2;uniform sampler2D reflectMap: TEXUNIT3;uniform samplerCUBE environmentMap: TEXUNIT4;// inverse view matrixuniform float3x4 inverseViewMatrix;// material propertiesuniform float mtlBumpMode;// 0 = none, 1 = normal, 2 = parallaxuniform float mtlSpecMode;// 0 = constant, 1 = mapuniform float mtlReflectMode;// 0 = none, 1 = constant, 2 = mapuniform float3 mtlEmissive;uniform float3 mtlAmbient;uniform float4 mtlDiffuse;uniform float4 mtlSpecularShininess; // rgb = specular, a = shininessuniform float mtlReflectivity;// scene propertiesuniform float4 sceneFog; // rgb = color, a = densityuniform float3 sceneAmbient;// light propertiesstatic const int MAX_LIGHTS = 8;uniform float lightCount;uniform float lightType[MAX_LIGHTS]; // 0 = directional, 1 = spotuniform float3 lightPosition[MAX_LIGHTS]; // doubles as direction for directional lightsuniform float3 lightAttenuation[MAX_LIGHTS]; // usage: x + y*D + z*D^2uniform float3 lightAmbient[MAX_LIGHTS];uniform float3 lightDiffuseSpecular[MAX_LIGHTS]; // diffuse and specular colorfloat3 rgbToXyz( float3 rgb ) {return rgb * 2.0f - 1.0f;}void main( in Input input, out float4 color : COLOR ) {input.normal = normalize( input.normal );// normal or parallax mappingif (mtlBumpMode > 0.0f) {// normalize these if neededinput.tangent = normalize( input.tangent );input.binormal = normalize( input.binormal );// parallax mappingif (mtlBumpMode == 2.0f) {// apply parallax mappingfloat bumpScale = 0.05f;float fDepth = 0.0f;float2 vHalfOffset = float2( 0.0f, 0.0f );float2 eyeVector = float2( dot( input.position, input.tangent ),   dot( input.position, input.binormal ) );for (int i = 0; i < 3; ++i) {fDepth = (fDepth + (1.0f - tex2D( bumpMap, input.texCoord + vHalfOffset ).a)) * 0.5f;vHalfOffset = normalize( eyeVector ).xy * fDepth * bumpScale;}input.texCoord += vHalfOffset;}// apply normal mapping by sampling our bump map and multiplying by tbnfloat3 bump = rgbToXyz( tex2D( bumpMap, input.texCoord ).rgb );input.normal = normalize( input.tangent * bump.x +  input.binormal * bump.y +  input.normal * bump.z );}// declare a float3 to hold our diffuse colorfloat3 diffuse;// apply reflection mappingif (mtlReflectMode == 1.0f) {// get the reflection vector in eye space// multiply it by inverse view matrix to get it into world spacefloat3 reflectCoord = reflect( input.position, input.normal );reflectCoord = mul( inverseViewMatrix, float4( reflectCoord, 0.0f ) ).xyz;// lerp based on reflectivity constantdiffuse = lerp( tex2D( diffuseMap, input.texCoord ).rgb,texCUBE( environmentMap, reflectCoord ).rgb,mtlReflectivity );} else if (mtlReflectMode == 2.0f) {// get the reflection vector in eye space// multiply it by inverse view matrix to get it into world spacefloat3 reflectCoord = reflect( input.position, input.normal );reflectCoord = mul( inverseViewMatrix, float4( reflectCoord, 0.0f ) ).xyz;// lerp based on sampled reflection mapdiffuse = lerp( tex2D( diffuseMap, input.texCoord ).rgb,texCUBE( environmentMap, reflectCoord ).rgb,tex2D( reflectMap, input.texCoord ).r );} elsediffuse = tex2D( diffuseMap, input.texCoord ).rgb;// multiply diffuse by material diffusediffuse *= mtlDiffuse.rgb;// declare a float4 to hold our specular colorfloat4 specular;if (mtlSpecMode == 0.0f)specular = mtlSpecularShininess;elsespecular = tex2D( specularMap, input.texCoord ).rgba;// now we compute lightingfloat3 intensity = mtlEmissive + mtlAmbient*sceneAmbient;float3 eyeDir = -normalize( input.position );for (int i = 0; i < lightCount && i < MAX_LIGHTS; ++i) {// for each light// first compute direction and attenuationfloat3 lightDir;float attenuation;if (lightType == 0) {// directional lightlightDir = -lightPosition;attenuation = 1.0f;} else {// point lightlightDir = lightPosition - input.position;float dist = length( lightDir );lightDir /= dist;attenuation = 1.0f/(lightAttenuation.x +lightAttenuation.y * dist +lightAttenuation.z * dist * dist);}// compute the half vector for specularityfloat3 halfVec = normalize( (lightDir + eyeDir) * 0.5f );// compute N.L and N.Hfloat nDotL = saturate( dot( input.normal, lightDir ) );float nDotH = saturate( dot( input.normal, halfVec ) );// determine the amount to increase the intensity by// we add ambient into this term because each light can contribute ambiently,// but only when an object is near the light; it attenuates like diffuse and specular// if overall ambient is wanted, use scene ambientfloat3 increase = mtlAmbient*lightAmbient +  (diffuse*nDotL + specular.rgb*pow( nDotH, specular.a )*saturate( nDotL*5.0f )) * lightDiffuseSpecular;// weight by attenuationintensity += attenuation * increase;}// compute the fog amount: e^-(density * z)float fogAmount = saturate( pow( 2.71828183f, -sceneFog.a * input.position.z ) );// finally, compute fragment colorcolor = float4( lerp( intensity, sceneFog.rgb, fogAmount ), mtlDiffuse.a );}The errors are in the for loop for the lights where I try to access arrays of light parameters. In OpenGL NV30 Fragment Program, I'm getting:error C5043: profile requires index expression to be compile-time constantanderror C5013: profile does not support "for" statements and "for" could not be unrolled.In OpenGL NV40 Fragment Program, I'm getting:error C6013: Only arrays of texcoords may be indexed in this profile, and only with a loop index variableWhat I'm trying to do is use static branching to loop through the arrays of light properties, but it appears that this doesn't work. Is there another way to do this? (Do I manually have to unroll the loop? I put a upper bound of MAX_LIGHTS on the loop, so I'd think that would fix issues, but apparently not...)EDIT: Well, it compiles if I do:for (int i = 0; i < MAX_LIGHTS; ++i) {if (i >= lightCount)continue;...Which I believe is still static branching. I can't test it on my current computer (older graphics card), but is this a good approach to take in terms of efficiency? If I do this, the loop is required to repeat the max number of times.   
  You could dofor (int i = 0; i < lightCount; ++i)or using break makes more sense than using continue.for (int i = 0; i < MAX_LIGHTS; ++i){if (i >= lightCount)break;}It should be alright since all fragments will execute the same number of loops.   