GL: added BufferTexture::resetBuffer().

doc/changelog.dox

@@ -129,6 +129,8 @@ See also:
     @ref Corrade::Containers::ArrayView instead of @ref std::initializer_list
     in order to allow passing runtime-sized lists (see
     [mosra/magnum#403](https://github.com/mosra/magnum/pull/403))
+-   Added an ability to remove a buffer from a @ref GL::BufferTexture using
+    @ref GL::BufferTexture::resetBuffer() "resetBuffer()"
 
 @subsubsection changelog-latest-changes-math Math library
 

src/Magnum/GL/BufferTexture.cpp

@@ -27,6 +27,7 @@
 
 #if !defined(MAGNUM_TARGET_GLES2) && !defined(MAGNUM_TARGET_WEBGL)
 #include "Magnum/GL/Buffer.h"
+#include "Magnum/GL/BufferTextureFormat.h"
 #include "Magnum/GL/Context.h"
 #include "Magnum/GL/Extensions.h"
 #include "Magnum/GL/Implementation/State.h"
@@ -80,7 +81,7 @@ Int BufferTexture::size() {
 
 BufferTexture& BufferTexture::setBuffer(const BufferTextureFormat internalFormat, Buffer& buffer) {
     buffer.createIfNotAlready();
-    (this->*Context::current().state().texture->setBufferImplementation)(internalFormat, buffer);
+    (this->*Context::current().state().texture->setBufferImplementation)(internalFormat, &buffer);
     return *this;
 }
 
@@ -90,21 +91,21 @@ BufferTexture& BufferTexture::setBuffer(const BufferTextureFormat internalFormat
     return *this;
 }
 
-void BufferTexture::setBufferImplementationDefault(BufferTextureFormat internalFormat, Buffer& buffer) {
+void BufferTexture::setBufferImplementationDefault(BufferTextureFormat internalFormat, Buffer* buffer) {
     bindInternal();
-    glTexBuffer(GL_TEXTURE_BUFFER, GLenum(internalFormat), buffer.id());
+    glTexBuffer(GL_TEXTURE_BUFFER, GLenum(internalFormat), buffer ? buffer->id() : 0);
 }
 
 #ifdef MAGNUM_TARGET_GLES
-void BufferTexture::setBufferImplementationEXT(BufferTextureFormat internalFormat, Buffer& buffer) {
+void BufferTexture::setBufferImplementationEXT(BufferTextureFormat internalFormat, Buffer* buffer) {
     bindInternal();
-    glTexBufferEXT(GL_TEXTURE_BUFFER, GLenum(internalFormat), buffer.id());
+    glTexBufferEXT(GL_TEXTURE_BUFFER, GLenum(internalFormat), buffer ? buffer->id() : 0);
 }
 #endif
 
 #ifndef MAGNUM_TARGET_GLES
-void BufferTexture::setBufferImplementationDSA(const BufferTextureFormat internalFormat, Buffer& buffer) {
-    glTextureBuffer(id(), GLenum(internalFormat), buffer.id());
+void BufferTexture::setBufferImplementationDSA(const BufferTextureFormat internalFormat, Buffer* buffer) {
+    glTextureBuffer(id(), GLenum(internalFormat), buffer ? buffer->id() : 0);
 }
 #endif
 
@@ -126,5 +127,12 @@ void BufferTexture::setBufferRangeImplementationDSA(const BufferTextureFormat in
 }
 #endif
 
+BufferTexture& BufferTexture::resetBuffer() {
+    /* R8 is the default state according to ARB_texture_buffer_object, so use
+       that */
+    (this->*Context::current().state().texture->setBufferImplementation)(BufferTextureFormat::R8, nullptr);
+    return *this;
+}
+
 }}
 #endif

src/Magnum/GL/BufferTexture.h

@@ -209,8 +209,9 @@ class MAGNUM_GL_EXPORT BufferTexture: public AbstractTexture {
          * own data setting functions. If @gl_extension{ARB,direct_state_access}
          * (part of OpenGL 4.5) is not available, the texture is bound before
          * the operation (if not already).
-         * @see @ref maxSize(), @fn_gl2_keyword{TextureBuffer,TexBuffer},
-         *      eventually @fn_gl{ActiveTexture}, @fn_gl{BindTexture} and
+         * @see @ref maxSize(), @ref resetBuffer(),
+         *      @fn_gl2_keyword{TextureBuffer,TexBuffer}, eventually
+         *      @fn_gl{ActiveTexture}, @fn_gl{BindTexture} and
          *      @fn_gl_keyword{TexBuffer}
          */
         BufferTexture& setBuffer(BufferTextureFormat internalFormat, Buffer& buffer);
@@ -228,13 +229,23 @@ class MAGNUM_GL_EXPORT BufferTexture: public AbstractTexture {
          * own data setting functions. If @gl_extension{ARB,direct_state_access}
          * (part of OpenGL 4.5) is not available, the texture is bound before
          * the operation (if not already).
-         * @see @ref maxSize(), @fn_gl2_keyword{TextureBufferRange,TexBufferRange},
-         *      eventually @fn_gl{ActiveTexture}, @fn_gl{BindTexture} and
+         * @see @ref maxSize(), @ref resetBuffer(),
+         *      @fn_gl2_keyword{TextureBufferRange,TexBufferRange}, eventually
+         *      @fn_gl{ActiveTexture}, @fn_gl{BindTexture} and
          *      @fn_gl_keyword{TexBufferRange}
          * @requires_gl43 Extension @gl_extension{ARB,texture_buffer_range}
          */
         BufferTexture& setBuffer(BufferTextureFormat internalFormat, Buffer& buffer, GLintptr offset, GLsizeiptr size);
 
+        /**
+         * @brief Remove existing buffer from the texture
+         * @return Reference to self (for method chaining)
+         * @m_since_latest
+         *
+         * @see @ref setBuffer()
+         */
+        BufferTexture& resetBuffer();
+
         /* Overloads to remove WTF-factor from method chaining order */
         #ifndef DOXYGEN_GENERATING_OUTPUT
         BufferTexture& setLabel(const std::string& label) {
@@ -250,12 +261,12 @@ class MAGNUM_GL_EXPORT BufferTexture: public AbstractTexture {
     private:
         explicit BufferTexture(GLuint id, ObjectFlags flags): AbstractTexture{id, GL_TEXTURE_BUFFER, flags} {}
 
-        void MAGNUM_GL_LOCAL setBufferImplementationDefault(BufferTextureFormat internalFormat, Buffer& buffer);
+        void MAGNUM_GL_LOCAL setBufferImplementationDefault(BufferTextureFormat internalFormat, Buffer* buffer);
         #ifdef MAGNUM_TARGET_GLES
-        void MAGNUM_GL_LOCAL setBufferImplementationEXT(BufferTextureFormat internalFormat, Buffer& buffer);
+        void MAGNUM_GL_LOCAL setBufferImplementationEXT(BufferTextureFormat internalFormat, Buffer* buffer);
         #endif
         #ifndef MAGNUM_TARGET_GLES
-        void MAGNUM_GL_LOCAL setBufferImplementationDSA(BufferTextureFormat internalFormat, Buffer& buffer);
+        void MAGNUM_GL_LOCAL setBufferImplementationDSA(BufferTextureFormat internalFormat, Buffer* buffer);
         #endif
 
         void MAGNUM_GL_LOCAL setBufferRangeImplementationDefault(BufferTextureFormat internalFormat, Buffer& buffer, GLintptr offset, GLsizeiptr size);

src/Magnum/GL/Implementation/TextureState.h

@@ -105,7 +105,7 @@ struct TextureState {
     void(AbstractTexture::*invalidateSubImageImplementation)(GLint, const Vector3i&, const Vector3i&);
 
     #if !defined(MAGNUM_TARGET_GLES2) && !defined(MAGNUM_TARGET_WEBGL)
-    void(BufferTexture::*setBufferImplementation)(BufferTextureFormat, Buffer&);
+    void(BufferTexture::*setBufferImplementation)(BufferTextureFormat, Buffer*);
     void(BufferTexture::*setBufferRangeImplementation)(BufferTextureFormat, Buffer&, GLintptr, GLsizeiptr);
     #endif
 

src/Magnum/GL/Test/BufferTextureGLTest.cpp

@@ -47,6 +47,8 @@ struct BufferTextureGLTest: OpenGLTester {
     void setBuffer();
     void setBufferEmptyFirst();
     void setBufferOffset();
+
+    void resetBuffer();
 };
 
 BufferTextureGLTest::BufferTextureGLTest() {
@@ -58,7 +60,9 @@ BufferTextureGLTest::BufferTextureGLTest() {
 
               &BufferTextureGLTest::setBuffer,
               &BufferTextureGLTest::setBufferEmptyFirst,
-              &BufferTextureGLTest::setBufferOffset});
+              &BufferTextureGLTest::setBufferOffset,
+
+              &BufferTextureGLTest::resetBuffer});
 }
 
 void BufferTextureGLTest::construct() {
@@ -271,6 +275,43 @@ void BufferTextureGLTest::setBufferOffset() {
     MAGNUM_VERIFY_NO_GL_ERROR();
 }
 
+void BufferTextureGLTest::resetBuffer() {
+    #ifndef MAGNUM_TARGET_GLES
+    if(!Context::current().isExtensionSupported<Extensions::ARB::texture_buffer_object>())
+        CORRADE_SKIP(Extensions::ARB::texture_buffer_object::string() + std::string(" is not supported."));
+    #else
+    if(!Context::current().isExtensionSupported<Extensions::EXT::texture_buffer>())
+        CORRADE_SKIP(Extensions::EXT::texture_buffer::string() + std::string(" is not supported."));
+    #endif
+
+    BufferTexture texture;
+    Buffer buffer;
+    buffer.setData({nullptr, 16});
+    texture.setBuffer(BufferTextureFormat::RG8UI, buffer);
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    #ifdef MAGNUM_TARGET_GLES
+    if(Context::current().isVersionSupported(Version::GLES310))
+    #endif
+    {
+        CORRADE_COMPARE(texture.size(), 8);
+    }
+
+    texture.resetBuffer();
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    #ifdef MAGNUM_TARGET_GLES
+    if(!Context::current().isVersionSupported(Version::GLES310))
+        CORRADE_SKIP("OpenGL ES 3.1 not supported, skipping image size testing.");
+    #endif
+
+    CORRADE_COMPARE(texture.size(), 0);
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+}
+
 }}}}
 
 CORRADE_TEST_MAIN(Magnum::GL::Test::BufferTextureGLTest)