OpenGL: refactor texture allocation.

Move texture allocation in an AllocateTexture() local.

Use the GL target to determine the choice of allocation call, not
the Dawn TextureDimension. This leaves TargetForTexture() and
TargetForTextureViewDimension() as the authorities on Dawn -> GL
conversion.

Change-Id: Ia31fbba9a8e71a9ce8dd9c89676dbc51d8848bb5
Bug: dawn:593
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/85080
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Stephen White <senorblanco@chromium.org>

src/dawn/native/opengl/TextureGL.cpp

@@ -41,6 +41,7 @@ namespace dawn::native::opengl {
                         }
                     }
                 case wgpu::TextureDimension::e3D:
+                    ASSERT(descriptor->sampleCount == 1);
                     return GL_TEXTURE_3D;
 
                 case wgpu::TextureDimension::e1D:
@@ -63,8 +64,12 @@ namespace dawn::native::opengl {
                     ASSERT(sampleCount == 1);
                     return GL_TEXTURE_2D_ARRAY;
                 case wgpu::TextureViewDimension::Cube:
+                    ASSERT(sampleCount == 1);
+                    ASSERT(arrayLayerCount == 6);
                     return GL_TEXTURE_CUBE_MAP;
                 case wgpu::TextureViewDimension::CubeArray:
+                    ASSERT(sampleCount == 1);
+                    ASSERT(arrayLayerCount % 6 == 0);
                     return GL_TEXTURE_CUBE_MAP_ARRAY;
                 case wgpu::TextureViewDimension::e3D:
                     return GL_TEXTURE_3D;
@@ -129,6 +134,34 @@ namespace dawn::native::opengl {
             return false;
         }
 
+        void AllocateTexture(const OpenGLFunctions& gl,
+                             GLenum target,
+                             GLsizei samples,
+                             GLuint levels,
+                             GLenum internalFormat,
+                             const Extent3D& size) {
+            // glTextureView() requires the value of GL_TEXTURE_IMMUTABLE_FORMAT for origtexture to
+            // be GL_TRUE, so the storage of the texture must be allocated with glTexStorage*D.
+            // https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glTextureView.xhtml
+            switch (target) {
+                case GL_TEXTURE_2D_ARRAY:
+                case GL_TEXTURE_3D:
+                    gl.TexStorage3D(target, levels, internalFormat, size.width, size.height,
+                                    size.depthOrArrayLayers);
+                    break;
+                case GL_TEXTURE_2D:
+                case GL_TEXTURE_CUBE_MAP:
+                    gl.TexStorage2D(target, levels, internalFormat, size.width, size.height);
+                    break;
+                case GL_TEXTURE_2D_MULTISAMPLE:
+                    gl.TexStorage2DMultisample(target, samples, internalFormat, size.width,
+                                               size.height, true);
+                    break;
+                default:
+                    UNREACHABLE();
+            }
+        }
+
     }  // namespace
 
     // Texture
@@ -137,44 +170,13 @@ namespace dawn::native::opengl {
         : Texture(device, descriptor, GenTexture(device->gl), TextureState::OwnedInternal) {
         const OpenGLFunctions& gl = ToBackend(GetDevice())->gl;
 
-        uint32_t width = GetWidth();
-        uint32_t height = GetHeight();
         uint32_t levels = GetNumMipLevels();
-        uint32_t arrayLayers = GetArrayLayers();
-        uint32_t sampleCount = GetSampleCount();
 
         const GLFormat& glFormat = GetGLFormat();
 
         gl.BindTexture(mTarget, mHandle);
 
-        // glTextureView() requires the value of GL_TEXTURE_IMMUTABLE_FORMAT for origtexture to be
+        AllocateTexture(gl, mTarget, GetSampleCount(), levels, glFormat.internalFormat, GetSize());
-        // GL_TRUE, so the storage of the texture must be allocated with glTexStorage*D.
-        // https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glTextureView.xhtml
-        switch (GetDimension()) {
-            case wgpu::TextureDimension::e2D:
-                if (arrayLayers > 1) {
-                    ASSERT(!IsMultisampledTexture());
-                    gl.TexStorage3D(mTarget, levels, glFormat.internalFormat, width, height,
-                                    arrayLayers);
-                } else {
-                    if (IsMultisampledTexture()) {
-                        gl.TexStorage2DMultisample(mTarget, sampleCount, glFormat.internalFormat,
-                                                   width, height, true);
-                    } else {
-                        gl.TexStorage2D(mTarget, levels, glFormat.internalFormat, width, height);
-                    }
-                }
-                break;
-            case wgpu::TextureDimension::e3D:
-                ASSERT(!IsMultisampledTexture());
-                ASSERT(arrayLayers == 1);
-                gl.TexStorage3D(mTarget, levels, glFormat.internalFormat, width, height,
-                                GetDepth());
-                break;
-
-            case wgpu::TextureDimension::e1D:
-                UNREACHABLE();
-        }
 
         // The texture is not complete if it uses mipmapping and not all levels up to
         // MAX_LEVEL have been defined.