如何从 OpenGL GLSL 代码转换为 OpenGL ES GLSL 代码

Question

我正在尝试将 glsl for opengl 转换为 glsl for opengl es。

这是我要翻译的glsl代码。

• 对于顶点着色器

  varying vec2 texcoord0;
  varying vec2 texcoord1;
  varying vec2 texcoord2;
  varying vec2 texcoord3;
  varying vec2 texcoord4;
  varying vec2 texdim0;
  varying vec2 texcoordLUT;
  uniform float sharpness;
  void main()
  {
      gl_Position = ftransform();
      texcoord0 = vec2(gl_TextureMatrix[0] * gl_MultiTexCoord0);
      texcoordLUT = vec2(gl_TextureMatrix[1] * gl_MultiTexCoord1);
      texdim0 = vec2 (abs(gl_TextureMatrix[0][0][0]),abs(gl_TextureMatrix[0][1][1]));
      texcoord1 = texcoord0 + vec2(-sharpness, -sharpness);
      texcoord2 = texcoord0 + vec2(+sharpness, -sharpness);
      texcoord3 = texcoord0 + vec2(+sharpness, +sharpness);
      texcoord4 = texcoord0 + vec2(-sharpness, +sharpness);
  }
  

• 对于片段着色器

  uniform float amount;
  uniform float vignette;
  uniform sampler4DRect tex0;
  uniform sampler1D tex1;
  varying vec2 texcoord0;
  varying vec2 texcoord1;
  varying vec2 texcoord2;
  varying vec2 texcoord3;
  varying vec2 texcoord4;
  varying vec2 texdim0;
  varying vec2 texcoordLUT;
  const vec4 one = vec4(1.0); 
  const vec4 two = vec4(2.0);
  const vec4 lumcoeff = vec4(0.299,0.587,0.114, 0.);
  vec4 vignetteFucntion(vec2 normalizedTexcoord)
  {
      normalizedTexcoord = 2.0 * normalizedTexcoord - 1.0;
      float r = length(normalizedTexcoord);
      return 1.0 - vec4(smoothstep(0.5,1.0,r)) + 0.5;
  }
  vec4 hardlight(vec4 a, vec4 b, float amount)
  {
      vec4 result;
      vec4 branch1;
      vec4 branch2;
      float luminance = dot(b,lumcoeff);
      float mixamount;
      mixamount = clamp((luminance - 0.45) * 10., 0., 1.);
      branch1 = two * a * b;
      branch2 = one - (two * (one - a) * (one - b));
      result =  mix(branch1,branch2, vec4(mixamount));
      return mix(a,result, amount);
  }
  void main (void) 
  {       
      vec2 normcoord = texcoord0/texdim0;
      vec4 vignetteResult = vignetteFucntion(normcoord);
      vec4 input0 = texture2DRect(tex0, texcoord0);
      vec4 input1 = texture2DRect(tex0, texcoord1);
      vec4 input2 = texture2DRect(tex0, texcoord2);
      vec4 input3 = texture2DRect(tex0, texcoord3);
      vec4 input4 = texture2DRect(tex0, texcoord4);
      vec4 sharpened = 5.0 * input0 - (input1 + input2 + input3 + input4);
      vec4 hardlighted = hardlight(sharpened,input0, .5);
      vec4 saturated = mix(vec4(dot(hardlighted,lumcoeff)), hardlighted, 0.75);
      vec4 result;
      result.r = texture1D(tex1, saturated.r).r;
      result.g = texture1D(tex1, saturated.g).g;
      result.b = texture1D(tex1, saturated.b).b;
      result.a = saturated.a;
      gl_FragColor = mix(input0, result *  (mix(vec4(1.0),vignetteResult, vignette)),amount);
  }
  

我想知道如何翻译gl_TextureMatrix[0]、gl_TextureMatrix[1]和gl_TextureMatrix[0][0][0]。它们是什么意思？

Answer 1

gl_TextureMatrix 是一个转换矩阵，用于转换纹理坐标（例如，如果要在静态形状上旋转或缩放纹理）。

它是标准 OpenGL 中已弃用的内置变量。在现代OpenGL/OpenGLES中处理这个问题的正确方法是声明自己的统一矩阵而不是使用内置的gl_TextureMatrix，并更新这些统一矩阵而不是对OpenGL的GL_TEXTURE_MATRIX执行旋转/平移。