[webgl] Implement GL_UNPACK_ROW_LENGTH (#21980)

Fixes: #21968

Author: sbc100

src/generated_struct_info32.json

@@ -308,6 +308,8 @@
         "File::DirectoryKind": 2,
         "File::SymlinkKind": 3,
         "File::UnknownKind": 0,
+        "GL_UNPACK_ALIGNMENT": 3317,
+        "GL_UNPACK_ROW_LENGTH": 3314,
         "ICANON": 2,
         "ICRNL": 256,
         "IEXTEN": 32768,

src/generated_struct_info64.json

@@ -308,6 +308,8 @@
         "File::DirectoryKind": 2,
         "File::SymlinkKind": 3,
         "File::UnknownKind": 0,
+        "GL_UNPACK_ALIGNMENT": 3317,
+        "GL_UNPACK_ROW_LENGTH": 3314,
         "ICANON": 2,
         "ICRNL": 256,
         "IEXTEN": 32768,

src/library_webgl.js

@@ -288,6 +288,7 @@ for (/**@suppress{duplicate}*/var i = 0; i < {{{ GL_POOL_TEMP_BUFFERS_SIZE }}};
 #endif
 
     unpackAlignment: 4, // default alignment is 4 bytes
+    unpackRowLength: 0,
 
     // Records a GL error condition that occurred, stored until user calls
     // glGetError() to fetch it. As per GLES2 spec, only the first error is
@@ -1235,8 +1236,10 @@ for (/**@suppress{duplicate}*/var i = 0; i < {{{ GL_POOL_TEMP_BUFFERS_SIZE }}};
   },
 
   glPixelStorei: (pname, param) => {
-    if (pname == 0xCF5 /* GL_UNPACK_ALIGNMENT */) {
+    if (pname == {{{ cDefs.GL_UNPACK_ALIGNMENT }}}) {
       GL.unpackAlignment = param;
+    } else if (pname == {{{ cDefs.GL_UNPACK_ROW_LENGTH }}}) {
+      GL.unpackRowLength = param;
     }
     GLctx.pixelStorei(pname, param);
   },
@@ -1548,15 +1551,15 @@ for (/**@suppress{duplicate}*/var i = 0; i < {{{ GL_POOL_TEMP_BUFFERS_SIZE }}};
     GLctx.compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, data ? {{{ makeHEAPView('U8', 'data', 'data+imageSize') }}} : null);
   },
 
-  $computeUnpackAlignedImageSize: (width, height, sizePerPixel, alignment) => {
+  $computeUnpackAlignedImageSize: (width, height, sizePerPixel) => {
     function roundedToNextMultipleOf(x, y) {
 #if GL_ASSERTIONS
       assert((y & (y-1)) === 0, 'Unpack alignment must be a power of 2! (Allowed values per WebGL spec are 1, 2, 4 or 8)');
 #endif
       return (x + y - 1) & -y;
     }
-    var plainRowSize = width * sizePerPixel;
-    var alignedRowSize = roundedToNextMultipleOf(plainRowSize, alignment);
+    var plainRowSize = (GL.unpackRowLength || width) * sizePerPixel;
+    var alignedRowSize = roundedToNextMultipleOf(plainRowSize, GL.unpackAlignment);
     return height * alignedRowSize;
   },
 
@@ -1600,7 +1603,7 @@ for (/**@suppress{duplicate}*/var i = 0; i < {{{ GL_POOL_TEMP_BUFFERS_SIZE }}};
   $emscriptenWebGLGetTexPixelData: (type, format, width, height, pixels, internalFormat) => {
     var heap = heapObjectForWebGLType(type);
     var sizePerPixel = colorChannelsInGlTextureFormat(format) * heap.BYTES_PER_ELEMENT;
-    var bytes = computeUnpackAlignedImageSize(width, height, sizePerPixel, GL.unpackAlignment);
+    var bytes = computeUnpackAlignedImageSize(width, height, sizePerPixel);
 #if GL_ASSERTIONS
     assert(pixels % heap.BYTES_PER_ELEMENT == 0, 'Pointer to texture data passed to texture get function must be aligned to the byte size of the pixel type!');
 #endif

src/struct_info.json

@@ -1204,6 +1204,13 @@
           "ALC_INVALID_ENUM"
         ]
     },
+    {
+        "file": "GL/gl.h",
+        "defines": [
+          "GL_UNPACK_ALIGNMENT",
+          "GL_UNPACK_ROW_LENGTH"
+        ]
+    },
     // ===========================================
     // WebGPU
     //   NOTE: This section is auto-generated.

test/test_browser.py

@@ -2193,6 +2193,11 @@ def test_cubegeom_pre2_vao2(self):
   def test_cubegeom_pre_vao_es(self):
     self.reftest('third_party/cubegeom/cubegeom_pre_vao_es.c', 'third_party/cubegeom/cubegeom_pre_vao.png', args=['-sFULL_ES2', '-lGL', '-lSDL'])
 
+  @requires_graphics_hardware
+  @no_swiftshader
+  def test_cubegeom_row_length(self):
+    self.reftest('third_party/cubegeom/cubegeom_pre_vao_es.c', 'third_party/cubegeom/cubegeom_pre_vao.png', args=['-sFULL_ES2', '-lGL', '-lSDL', '-DUSE_UNPACK_ROW_LENGTH'])
+
   @requires_graphics_hardware
   def test_cubegeom_u4fv_2(self):
     self.reftest('third_party/cubegeom/cubegeom_u4fv_2.c', 'third_party/cubegeom/cubegeom_u4fv_2.png', args=['-sLEGACY_GL_EMULATION', '-lGL', '-lSDL'])

test/third_party/cubegeom/cubegeom_pre_vao_es.c

@@ -55,14 +55,25 @@ int main(int argc, char *argv[])
     glBindTexture( GL_TEXTURE_2D, texture );
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
-    GLubyte textureData[16*16*4];
+#if USE_UNPACK_ROW_LENGTH
+#define ROW_SIZE 20
+#else
+#define ROW_SIZE 16
+#endif
+    GLubyte textureData[16*ROW_SIZE*4] = {0};
     for (int x = 0; x < 16; x++) {
       for (int y = 0; y < 16; y++) {
-        *((int*)&textureData[(x*16 + y) * 4]) = x*16 + ((y*16) << 8);
+        *((int*)&textureData[(x*ROW_SIZE + y) * 4]) = x*16 + ((y*16) << 8);
       }
     }
+#if USE_UNPACK_ROW_LENGTH
+    glPixelStorei(GL_UNPACK_ROW_LENGTH, ROW_SIZE);
+#endif
     glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, 
                   GL_RGBA, GL_UNSIGNED_BYTE, textureData );
+#if USE_UNPACK_ROW_LENGTH
+    glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
+#endif
 
     // Create a second texture