以下是一个性能较差的片段着色器。删除条件分支似乎并没有提高性能。只有150个多边形,我在Kindle Fire上获得10fps,在Galaxy S3上获得20fps。有没有想过要优化这个的最佳方式? iPad 2上的类似着色器运行30 + fps。关于具有8个纹理单元的opengl es多纹理着色器的想法
在下面的代码中,texture1到texture8绑定到八个纹理。 VertexTexturesOut1和VertexTexturesOut2从顶点着色器传递,并具有值0.0到1.0以指示要混合的着色量。我们的想法是混合景观的质感,让草混合均匀,放入泥土,岩石,沙子等设计片段着色时
uniform sampler2D texture1;
uniform sampler2D texture2;
uniform sampler2D texture3;
uniform sampler2D texture4;
uniform sampler2D texture5;
uniform sampler2D texture6;
uniform sampler2D texture7;
uniform sampler2D texture8;
varying mediump vec2 TextureCoordOut;
varying lowp vec4 VertexTexturesOut1;
varying lowp vec4 VertexTexturesOut2;
...
lowp vec4 Color = vec4(0.0, 0.0, 0.0, 0.0);
if (VertexTexturesOut1.x != 0.0) Color = Color + texture2D (texture1, TextureCoordOut) * VertexTexturesOut1.x;
if (VertexTexturesOut1.y != 0.0) Color = Color + texture2D (texture2, TextureCoordOut) * VertexTexturesOut1.y;
if (VertexTexturesOut1.z != 0.0) Color = Color + texture2D (texture3, TextureCoordOut) * VertexTexturesOut1.z;
if (VertexTexturesOut1.w != 0.0) Color = Color + texture2D (texture4, TextureCoordOut) * VertexTexturesOut1.w;
if (VertexTexturesOut2.x != 0.0) Color = Color + texture2D (texture5, TextureCoordOut) * VertexTexturesOut2.x;
if (VertexTexturesOut2.y != 0.0) Color = Color + texture2D (texture6, TextureCoordOut) * VertexTexturesOut2.y;
if (VertexTexturesOut2.z != 0.0) Color = Color + texture2D (texture7, TextureCoordOut) * VertexTexturesOut2.z;
if (VertexTexturesOut2.w != 0.0) Color = Color + texture2D (texture8, TextureCoordOut) * VertexTexturesOut2.w;
gl_FragColor = Color;
1.有这些if语句有什么意义?这真的比单纯乘法更快吗? 2.刺伤黑暗:也许同一个变量的多重赋值不是最优的?有一个'Color1'和'Color2'并添加这些? – 2013-02-12 18:16:12