Add love.graphics.copyTextureToBuffer and copyBufferToTexture.

src/modules/graphics/opengl/Graphics.cpp

@@ -1640,7 +1640,10 @@ void Graphics::initCapabilities()
 	capabilities.features[FEATURE_INSTANCING] = gl.isInstancingSupported();
 	capabilities.features[FEATURE_TEXEL_BUFFER] = gl.isBufferUsageSupported(BUFFERUSAGE_TEXEL);
 	capabilities.features[FEATURE_COPY_BUFFER] = gl.isCopyBufferSupported();
-	static_assert(FEATURE_MAX_ENUM == 12, "Graphics::initCapabilities must be updated when adding a new graphics feature!");
+	capabilities.features[FEATURE_COPY_BUFFER_TO_TEXTURE] = gl.isCopyBufferToTextureSupported();
+	capabilities.features[FEATURE_COPY_TEXTURE_TO_BUFFER] = gl.isCopyTextureToBufferSupported();
+	capabilities.features[FEATURE_COPY_RENDER_TARGET_TO_BUFFER] = gl.isCopyRenderTargetToBufferSupported();
+	static_assert(FEATURE_MAX_ENUM == 15, "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

@@ -1530,6 +1530,24 @@ bool OpenGL::isCopyBufferSupported() const
 	return GLAD_VERSION_3_1 || GLAD_ES_VERSION_3_0;
 }
 
+bool OpenGL::isCopyBufferToTextureSupported() const
+{
+	// Requires pixel unpack buffer binding support.
+	return GLAD_VERSION_2_0 || GLAD_ES_VERSION_3_0;
+}
+
+bool OpenGL::isCopyTextureToBufferSupported() const
+{
+	// Requires glGetTextureSubImage support.
+	return GLAD_VERSION_4_5;
+}
+
+bool OpenGL::isCopyRenderTargetToBufferSupported() const
+{
+	// Requires pixel pack buffer binding support.
+	return GLAD_VERSION_2_0 || GLAD_ES_VERSION_3_0;
+}
+
 int OpenGL::getMax2DTextureSize() const
 {
 	return std::max(max2DTextureSize, 1);

src/modules/graphics/opengl/OpenGL.h

@@ -372,6 +372,9 @@ public:
 	bool isBaseVertexSupported() const;
 	bool isMultiFormatMRTSupported() const;
 	bool isCopyBufferSupported() const;
+	bool isCopyBufferToTextureSupported() const;
+	bool isCopyTextureToBufferSupported() const;
+	bool isCopyRenderTargetToBufferSupported() const;
 
 	/**
 	 * Returns the maximum supported width or height of a texture.

src/modules/graphics/opengl/Texture.cpp

@@ -22,6 +22,7 @@
 
 #include "graphics/Graphics.h"
 #include "Graphics.h"
+#include "Buffer.h"
 #include "common/int.h"
 
 // STD
@@ -524,6 +525,75 @@ void Texture::readbackImageData(love::image::ImageData *data, int slice, int mip
 	gl.bindFramebuffer(OpenGL::FRAMEBUFFER_ALL, current_fbo);
 }
 
+void Texture::copyFromBuffer(love::graphics::Buffer *source, size_t sourceoffset, int sourcewidth, size_t size, int slice, int mipmap, const Rect &rect)
+{
+	// Higher level code does validation.
+
+	GLuint glbuffer = (GLuint) source->getHandle();
+	glBindBuffer(GL_PIXEL_UNPACK_BUFFER, glbuffer);
+
+	if (!isCompressed()) // Not supported in GL with compressed textures...
+		glPixelStorei(GL_UNPACK_ROW_LENGTH, sourcewidth);
+
+	// glTexSubImage and friends copy from the active pixel_unpack_buffer by
+	// treating the pointer as a byte offset.
+	const uint8 *byteoffset = (const uint8 *)(ptrdiff_t)sourceoffset;
+	uploadByteData(format, byteoffset, size, mipmap, slice, rect);
+
+	glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
+	glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+}
+
+void Texture::copyToBuffer(love::graphics::Buffer *dest, int slice, int mipmap, const Rect &rect, size_t destoffset, int destwidth, size_t size)
+{
+	// Higher level code does validation.
+
+	GLuint glbuffer = (GLuint) dest->getHandle();
+	glBindBuffer(GL_PIXEL_PACK_BUFFER, glbuffer);
+
+	if (!isCompressed()) // Not supported in GL with compressed textures...
+		glPixelStorei(GL_PACK_ROW_LENGTH, destwidth);
+
+	gl.bindTextureToUnit(this, 0, false);
+
+	bool isSRGB = false;
+	OpenGL::TextureFormat fmt = gl.convertPixelFormat(format, false, isSRGB);
+
+	// glTexSubImage and friends copy from the active pixel_unpack_buffer by
+	// treating the pointer as a byte offset.
+	uint8 *byteoffset = (uint8 *)(ptrdiff_t)destoffset;
+
+	if (GLAD_VERSION_4_5)
+	{
+		if (isCompressed())
+			glGetCompressedTextureSubImage(texture, mipmap, rect.x, rect.y, slice, rect.w, rect.h, 1, size, byteoffset);
+		else
+			glGetTextureSubImage(texture, mipmap, rect.x, rect.y, slice, rect.w, rect.h, 1, fmt.externalformat, fmt.type, size, byteoffset);
+	}
+	else if (fbo)
+	{
+		GLuint current_fbo = gl.getFramebuffer(OpenGL::FRAMEBUFFER_ALL);
+		gl.bindFramebuffer(OpenGL::FRAMEBUFFER_ALL, getFBO());
+
+		if (slice > 0 || mipmap > 0)
+		{
+			int layer = texType == TEXTURE_CUBE ? 0 : slice;
+			int face = texType == TEXTURE_CUBE ? slice : 0;
+			gl.framebufferTexture(GL_COLOR_ATTACHMENT0, texType, texture, mipmap, layer, face);
+		}
+
+		glReadPixels(rect.x, rect.y, rect.w, rect.h, fmt.externalformat, fmt.type, byteoffset);
+
+		if (slice > 0 || mipmap > 0)
+			gl.framebufferTexture(GL_COLOR_ATTACHMENT0, texType, texture, 0, 0, 0);
+
+		gl.bindFramebuffer(OpenGL::FRAMEBUFFER_ALL, current_fbo);
+	}
+
+	glPixelStorei(GL_PACK_ROW_LENGTH, 0);
+	glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
+}
+
 void Texture::setSamplerState(const SamplerState &s)
 {
 	if (s.depthSampleMode.hasValue && !gl.isDepthCompareSampleSupported())

src/modules/graphics/opengl/Texture.h

@@ -46,6 +46,9 @@ public:
 	bool loadVolatile() override;
 	void unloadVolatile() override;
 
+	void copyFromBuffer(love::graphics::Buffer *source, size_t sourceoffset, int sourcewidth, size_t size, int slice, int mipmap, const Rect &rect) override;
+	void copyToBuffer(love::graphics::Buffer *dest, int slice, int mipmap, const Rect &rect, size_t destoffset, int destwidth, size_t size) override;
+
 	void setSamplerState(const SamplerState &s) override;
 
 	ptrdiff_t getHandle() const override;