纹理拼接后的Wrap寻址

http://blog.csdn.net/xoyojank/article/details/3212425

 

 

拼接后的纹理:

正常的草地(不进行WRAP寻址):

WRAP = 5时的情况:

MinFilter = Linear时的情况:

shader实现:

sampler2D atlasTexture;
float4 texRect;   //(left, top, width, height) of uv
float2 invSize;   //(1/width, 1/height)
float4 uvRange;   //(left, top, right, bottom) of uv
float4 ps_main( float2 tex : TEXCOORD0 ) : COLOR
{
   // convert original uv to atlas uv's unit
   tex *= texRect.zw;

   float2 uv = tex - texRect.xy;
   // bring coordinates into normalized local texture coord [0..1]
   uv *= invSize;
   // if texture repeats then coords are > 1, use frc to bring
   // these coords back into [0, 1) interval.
   uv = frac(uv);
   // transform coords back to texture atlas coords
   uv = uv * texRect.zw + texRect.xy;
   // clamp to inside texture (to avoid bi-linear filter pulling in foreign texels)
   uv = clamp(uv, uvRange.xy, uvRange.zw);
   // use the original coords for mip-map calculation
   return tex2Dgrad(atlasTexture, uv, ddx(tex), ddy(tex));
}

sampler2D atlasTexture; float4 texRect; //(left, top, width, height) of uv float2 invSize; //(1/width, 1/height) float4 uvRange; //(left, top, right, bottom) of uv float4 ps_main( float2 tex : TEXCOORD0 ) : COLOR { // convert original uv to atlas uv's unit tex *= texRect.zw; float2 uv = tex - texRect.xy; // bring coordinates into normalized local texture coord [0..1] uv *= invSize; // if texture repeats then coords are > 1, use frc to bring // these coords back into [0, 1) interval. uv = frac(uv); // transform coords back to texture atlas coords uv = uv * texRect.zw + texRect.xy; // clamp to inside texture (to avoid bi-linear filter pulling in foreign texels) uv = clamp(uv, uvRange.xy, uvRange.zw); // use the original coords for mip-map calculation return tex2Dgrad(atlasTexture, uv, ddx(tex), ddy(tex)); } 

Reference:

ShaderX3 : Improved Batching via Texture Atlases