OSX WebGL using the wrong structure in all browsers

Question

I see a very strange problem on some OSX machines where, apparently, my WebGL program uses the wrong texture contents for painting.

I have a sprite pack where I buffer together a bunch of sprite quads into one call to call. I also use multiple texturing to further reduce the number of draw calls, drawing sprites for multiple textures in the same callback.

Each vertex has the following data:

 // 16 bytes
 float x;
 float y;
 float u;
 float v;

 // 16 bytes
 float texture_offset_x;
 float texture_offset_y;
 float texture_scale_width;
 float texture_scale_height;

 // 24 bytes
 float t0;
 float t1;
 float t2;
 float t3;
 float t4;
 float t5;

 // 8 bytes
 float width_scale;
 float height_scale;

 // 4 bytes
 unsigned byte r;
 unsigned byte g;
 unsigned byte b;
 unsigned byte a;

 // Texture sampler index
 float texture_index;

And the fragment shader combines drawing calls like this:

  "#version 100",
  "",
  "uniform lowp sampler2D sampler0;",
  "uniform lowp sampler2D sampler1;",
  "uniform lowp sampler2D sampler2;",
  "uniform lowp sampler2D sampler3;",
  "uniform lowp sampler2D sampler4;",
  "uniform lowp sampler2D sampler5;",
  "uniform lowp sampler2D sampler6;",
  "uniform lowp sampler2D sampler7;",
  "",
  "varying mediump vec2 vTextureCoord;",
  "varying lowp vec4 vTintColor;",
  "varying lowp float vTextureIndex;",
  "",
  "void main(void) {",
  "   lowp vec4 fragColors[8];",
  "   fragColors[0] = texture2D(sampler0, vTextureCoord);",
  "   fragColors[1] = texture2D(sampler1, vTextureCoord);",
  "   fragColors[2] = texture2D(sampler2, vTextureCoord);",
  "   fragColors[3] = texture2D(sampler3, vTextureCoord);",
  "   fragColors[4] = texture2D(sampler4, vTextureCoord);",
  "   fragColors[5] = texture2D(sampler5, vTextureCoord);",
  "   fragColors[6] = texture2D(sampler6, vTextureCoord);",
  "   fragColors[7] = texture2D(sampler7, vTextureCoord);",
  "",
  "   lowp float fragIncluded[8];",
  "",
  "   fragIncluded[0] = float(vTextureIndex <= 0.5);",
  "   fragIncluded[1] = float(vTextureIndex >= 0.5 && vTextureIndex < 1.5);",
  "   fragIncluded[2] = float(vTextureIndex >= 1.5 && vTextureIndex < 2.5);",
  "   fragIncluded[3] = float(vTextureIndex >= 2.5 && vTextureIndex < 3.5);",
  "   fragIncluded[4] = float(vTextureIndex >= 3.5 && vTextureIndex < 4.5);",
  "   fragIncluded[5] = float(vTextureIndex >= 4.5 && vTextureIndex < 5.5);",
  "   fragIncluded[6] = float(vTextureIndex >= 5.5 && vTextureIndex < 6.5);",
  "   fragIncluded[7] = float(vTextureIndex >= 6.5 && vTextureIndex < 7.5);",
  "",
  "   lowp vec4 fragColor = fragColors[0] * fragIncluded[0] + ",
  "                         fragColors[1] * fragIncluded[1] + ",
  "                         fragColors[2] * fragIncluded[2] + ",
  "                         fragColors[3] * fragIncluded[3] + ",
  "                         fragColors[4] * fragIncluded[4] + ",
  "                         fragColors[5] * fragIncluded[5] + ",
  "                         fragColors[6] * fragIncluded[6] + ",
  "                         fragColors[7] * fragIncluded[7];",
  "",
  "   gl_FragColor = fragColor * vTintColor;",
  "}"

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URL-: https://tinytappers.bigvikinggames.com/

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Answer 1

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