How to make a Sun (physical)
Author
There you go...
struct SkydomeVSOutput{ float4 Position : POSITION; float2 TexCoord : TEXCOORD0; float3 UPosition : TEXCOORD1;};struct SkydomePSOutput{ float4 Color : COLOR0;};SkydomeVSOutput SkydomeVS(float4 inPos : POSITION, float2 inTexCoord : TEXCOORD0){ SkydomeVSOutput output = (SkydomeVSOutput)0; float4x4 ViewProjection = mul(xView, xProj); float4x4 WorldViewProjection = mul(xWorld, ViewProjection); output.Position = mul(inPos, WorldViewProjection); inTexCoord.x /= 1.6; output.TexCoord = inTexCoord; output.UPosition = inPos; return output;}SkydomePSOutput SkydomePS(float2 inTexCoord : TEXCOORD0, float3 inUPos : TEXCOORD1){ SkydomePSOutput output = (SkydomePSOutput)0; output.Color = ambientColor * ambientIntensity; float3 finalSunPosition = float3(0.0f, 0.0f, 0.0f); float3 SunPosNoon = float3(1.0f, 1.0f, 0.0f); float3 SunPosSundown = float3(0.0f, 0.0f, 1.0f); float3 SunPosNight = float3(0.0f, 0.0f, 0.0f); float3 SunPosSunrise = float3(0.0f, 0.0f, -1.0f); if(xDaytimeNoon) { finalSunPosition += lerp(SunPosNoon, SunPosSundown, xTime); } if(xDaytimeSundown) { //finalSunPosition = SunPosNight; finalSunPosition += lerp(SunPosSundown, SunPosNight, xTime); } if(xDaytimeNight) { finalSunPosition += lerp(SunPosNight, SunPosSunrise, xTime); } if(xDaytimeSunrise) { finalSunPosition += lerp(SunPosSunrise, SunPosNoon, xTime); } // Calculating Sun float3 normal = normalize(inUPos); float3 sun = normalize(finalSunPosition); float SunDot = dot(sun, normal); vector sunVec = 0.5f * pow( max(0, SunDot), 300.0f ); float4 noon = float4(tex2D(SkydomeNoonTextureSampler, inTexCoord) + float4(0.1, 0.1, 0.1, 0)); float4 sundown = float4(tex2D(SkydomeSundownTextureSampler, inTexCoord) + float4(0.6, 0.15, 0.15, 0)); float4 night = float4(tex2D(SkydomeNightTextureSampler, inTexCoord) + float4(0, 0, 0.3, 0) + float4(-0.2, -0.2, -0.2, 0)); if(xDaytimeNoon) { output.Color += lerp(noon, sundown, xTime); output.Color += sunVec; } if(xDaytimeSundown) { output.Color += lerp(sundown, night, xTime); output.Color += sunVec; } if(xDaytimeNight) { output.Color += lerp(night, sundown, xTime); output.Color += sunVec; } if(xDaytimeSunrise) { output.Color += lerp(sundown, noon, xTime); output.Color += sunVec; } return output;}technique Skydome{ pass Pass0 { VertexShader = compile vs_2_0 SkydomeVS(); PixelShader = compile ps_2_0 SkydomePS(); // Render States ZWriteEnable = false; FillMode = Solid; }}
hmm this has a lot of conditions in it, i don't know if thats good in a pixel shader performance wise.
i think it's better to compute the sun position on the cpu (for example by rotating it around an axis as i showed you) and use a simple variable that represents the current time of day in the range of 0 (midnight) to 1 (noon) to blend those textures.
for example like this:
this would make your night texture fade out and disappear at around 1/3 of the day. no lerps needed.
But back to your question, if you multiply "sunVec" with some color value, you don't get the desired results?
(you can actually render the sun at night too because it's on the other side of the "earth" just like in real life :-))
Oh, btw you can define "sunVec" just as a float3 or float4. it said "vector" because i pasted that from some old sloppy code :)
i think it's better to compute the sun position on the cpu (for example by rotating it around an axis as i showed you) and use a simple variable that represents the current time of day in the range of 0 (midnight) to 1 (noon) to blend those textures.
for example like this:
float4 night = float4(tex2D(SkydomeNightTextureSampler, inTexCoord));night *= 1.0f - saturate(time_of_day * 1.5);this would make your night texture fade out and disappear at around 1/3 of the day. no lerps needed.
But back to your question, if you multiply "sunVec" with some color value, you don't get the desired results?
if(xDaytimeNoon) output.Color += lerp(noon, sundown, xTime); if(xDaytimeSundown) output.Color += lerp(sundown, night, xTime); if(xDaytimeNight) output.Color += lerp(night, sundown, xTime); if(xDaytimeSunrise) output.Color += lerp(sundown, noon, xTime); output.Color += sunVec * float4(1.0, 0, 0, 1.0f); //somecolor(you can actually render the sun at night too because it's on the other side of the "earth" just like in real life :-))
Oh, btw you can define "sunVec" just as a float3 or float4. it said "vector" because i pasted that from some old sloppy code :)
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement