学步园

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

Reference:

ShaderX3 : Improved Batching via Texture Atlases