Add love.graphics.copyBuffer.

src/modules/graphics/opengl/Buffer.cpp

@@ -253,6 +253,14 @@ void Buffer::fill(size_t offset, size_t size, const void *data)
 	}
 }
 
+void Buffer::copyTo(love::graphics::Buffer *dest, size_t sourceoffset, size_t destoffset, size_t size)
+{
+	gl.bindBuffer(BUFFERTYPE_COPY_SOURCE, buffer);
+	gl.bindBuffer(BUFFERTYPE_COPY_DEST, ((Buffer *) dest)->buffer);
+
+	glCopyBufferSubData(GL_COPY_READ_BUFFER, GL_COPY_WRITE_BUFFER, sourceoffset, destoffset, size);
+}
+
 } // opengl
 } // graphics
 } // love

src/modules/graphics/opengl/Buffer.h

@@ -53,6 +53,7 @@ public:
 	void *map(MapType map, size_t offset, size_t size) override;
 	void unmap(size_t usedoffset, size_t usedsize) override;
 	void fill(size_t offset, size_t size, const void *data) override;
+	void copyTo(love::graphics::Buffer *dest, size_t sourceoffset, size_t destoffset, size_t size) override;
 
 	ptrdiff_t getHandle() const override { return buffer; };
 	ptrdiff_t getTexelBufferHandle() const override { return texture; };

src/modules/graphics/opengl/Graphics.cpp

@@ -1531,7 +1531,8 @@ void Graphics::initCapabilities()
 	capabilities.features[FEATURE_GLSL4] = GLAD_ES_VERSION_3_1 || (gl.isCoreProfile() && GLAD_VERSION_4_3);
 	capabilities.features[FEATURE_INSTANCING] = gl.isInstancingSupported();
 	capabilities.features[FEATURE_TEXEL_BUFFER] = gl.isBufferTypeSupported(BUFFERTYPE_TEXEL);
-	static_assert(FEATURE_MAX_ENUM == 11, "Graphics::initCapabilities must be updated when adding a new graphics feature!");
+	capabilities.features[FEATURE_COPY_BUFFER] = gl.isBufferTypeSupported(BUFFERTYPE_COPY_SOURCE);
+	static_assert(FEATURE_MAX_ENUM == 12, "Graphics::initCapabilities must be updated when adding a new graphics feature!");
 
 	capabilities.limits[LIMIT_POINT_SIZE] = gl.getMaxPointSize();
 	capabilities.limits[LIMIT_TEXTURE_SIZE] = gl.getMax2DTextureSize();

src/modules/graphics/opengl/OpenGL.cpp

@@ -621,6 +621,8 @@ GLenum OpenGL::getGLBufferType(BufferType type)
 		case BUFFERTYPE_INDEX: return GL_ELEMENT_ARRAY_BUFFER;
 		case BUFFERTYPE_TEXEL: return GL_TEXTURE_BUFFER;
 		case BUFFERTYPE_SHADER_STORAGE: return GL_SHADER_STORAGE_BUFFER;
+		case BUFFERTYPE_COPY_SOURCE: return GL_COPY_READ_BUFFER;
+		case BUFFERTYPE_COPY_DEST: return GL_COPY_WRITE_BUFFER;
 		case BUFFERTYPE_MAX_ENUM: return GL_ZERO;
 	}
 
@@ -1444,6 +1446,9 @@ bool OpenGL::isBufferTypeSupported(BufferType type) const
 		return GLAD_VERSION_3_1;
 	case BUFFERTYPE_SHADER_STORAGE:
 		return (GLAD_VERSION_4_3 && isCoreProfile()) || GLAD_ES_VERSION_3_1;
+	case BUFFERTYPE_COPY_SOURCE:
+	case BUFFERTYPE_COPY_DEST:
+		return GLAD_VERSION_3_1 || GLAD_ES_VERSION_3_0;
 	case BUFFERTYPE_MAX_ENUM:
 		return false;
 	}