2 files changed, 71 insertions, 9 deletions

diff --git a/src/gui/opengl/qopengltexture.cpp b/src/gui/opengl/qopengltexture.cpp
index 43acd0a0c3..8bdbdba6f7 100644
--- a/src/gui/opengl/qopengltexture.cpp
+++ b/src/gui/opengl/qopengltexture.cpp
@@ -347,7 +347,6 @@ void QOpenGLTexturePrivate::allocateMutableStorage()
         break;
 
     case QOpenGLTexture::Target2D:
-    case QOpenGLTexture::TargetCubeMap:
     case QOpenGLTexture::TargetRectangle:
         for (int level = 0; level < mipLevels; ++level)
             texFuncs->glTextureImage2D(textureId, target, bindingTarget, level, format,
@@ -357,6 +356,29 @@ void QOpenGLTexturePrivate::allocateMutableStorage()
                                        QOpenGLTexture::RGBA, QOpenGLTexture::UInt8, 0);
         break;
 
+    case QOpenGLTexture::TargetCubeMap: {
+        // Cubemaps are the odd one out. We have to allocate storage for each
+        // face and miplevel using the special cubemap face targets rather than
+        // GL_TARGET_CUBEMAP.
+        const QOpenGLTexture::CubeMapFace faceTargets[] = {
+            QOpenGLTexture::CubeMapPositiveX, QOpenGLTexture::CubeMapNegativeX,
+            QOpenGLTexture::CubeMapPositiveY, QOpenGLTexture::CubeMapNegativeY,
+            QOpenGLTexture::CubeMapPositiveZ, QOpenGLTexture::CubeMapNegativeZ
+        };
+
+        for (int faceTarget = 0; faceTarget < 6; ++faceTarget) {
+            for (int level = 0; level < mipLevels; ++level) {
+                texFuncs->glTextureImage2D(textureId, faceTargets[faceTarget], bindingTarget,
+                                           level, format,
+                                           mipLevelSize(level, dimensions[0]),
+                                           mipLevelSize(level, dimensions[1]),
+                                           0,
+                                           QOpenGLTexture::RGBA, QOpenGLTexture::UInt8, 0);
+            }
+        }
+        break;
+    }
+
     case QOpenGLTexture::Target2DArray:
         if (features.testFlag(QOpenGLTexture::TextureArrays)) {
             for (int level = 0; level < mipLevels; ++level)
diff --git a/src/gui/opengl/qopengltexturehelper.cpp b/src/gui/opengl/qopengltexturehelper.cpp
index 69ad498aa7..1f44a81276 100644
--- a/src/gui/opengl/qopengltexturehelper.cpp
+++ b/src/gui/opengl/qopengltexturehelper.cpp
@@ -478,11 +478,31 @@ void QOpenGLTextureHelper::qt_TextureImage3D(GLuint texture, GLenum target, GLen
 
 void QOpenGLTextureHelper::qt_TextureImage2D(GLuint texture, GLenum target, GLenum bindingTarget, GLint level, GLenum internalFormat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid *pixels)
 {
+    // For cubemaps we can't use the standard DSA emulation as it is illegal to
+    // try to bind a texture to one of the cubemap face targets. So we force the
+    // target and binding target to the cubemap values in this case.
     GLint oldTexture;
-    glGetIntegerv(bindingTarget, &oldTexture);
-    glBindTexture(target, texture);
-    glTexImage2D(target, level, internalFormat, width, height, border, format, type, pixels);
-    glBindTexture(target, oldTexture);
+
+    switch (target) {
+    case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
+    case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
+    case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
+    case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
+    case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
+    case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
+        glGetIntegerv(GL_TEXTURE_BINDING_CUBE_MAP, &oldTexture);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, texture);
+        glTexImage2D(target, level, internalFormat, width, height, border, format, type, pixels);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, oldTexture);
+        break;
+
+    default:
+        glGetIntegerv(bindingTarget, &oldTexture);
+        glBindTexture(target, texture);
+        glTexImage2D(target, level, internalFormat, width, height, border, format, type, pixels);
+        glBindTexture(target, oldTexture);
+        break;
+    }
 }
 
 void QOpenGLTextureHelper::qt_TextureImage1D(GLuint texture, GLenum target, GLenum bindingTarget, GLint level, GLenum internalFormat, GLsizei width, GLint border, GLenum format, GLenum type, const GLvoid *pixels)
@@ -505,11 +525,31 @@ void QOpenGLTextureHelper::qt_TextureSubImage3D(GLuint texture, GLenum target, G
 
 void QOpenGLTextureHelper::qt_TextureSubImage2D(GLuint texture, GLenum target, GLenum bindingTarget, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid *pixels)
 {
+    // For cubemaps we can't use the standard DSA emulation as it is illegal to
+    // try to bind a texture to one of the cubemap face targets. So we force the
+    // target and binding target to the cubemap values in this case.
     GLint oldTexture;
-    glGetIntegerv(bindingTarget, &oldTexture);
-    glBindTexture(target, texture);
-    glTexSubImage2D(target, level, xoffset, yoffset, width, height, format, type, pixels);
-    glBindTexture(target, oldTexture);
+
+    switch (target) {
+    case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
+    case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
+    case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
+    case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
+    case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
+    case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
+        glGetIntegerv(GL_TEXTURE_BINDING_CUBE_MAP, &oldTexture);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, texture);
+        glTexSubImage2D(target, level, xoffset, yoffset, width, height, format, type, pixels);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, oldTexture);
+        break;
+
+    default:
+        glGetIntegerv(bindingTarget, &oldTexture);
+        glBindTexture(target, texture);
+        glTexSubImage2D(target, level, xoffset, yoffset, width, height, format, type, pixels);
+        glBindTexture(target, oldTexture);
+        break;
+    }
 }
 
 void QOpenGLTextureHelper::qt_TextureSubImage1D(GLuint texture, GLenum target, GLenum bindingTarget, GLint level, GLint xoffset, GLsizei width, GLenum format, GLenum type, const GLvoid *pixels)