OPENGL: Redesign blitting system. Add basics for aspect correction.

Removed the extra surface in GLTexture. Now there are copies of the texture data in their original format (so engine can get the original data when lockScreen or grabOverlay is called). This copies will be updated when the engine calls a function that modifies the game screen/overlay, and the textures will be marked as dirty. When updating screen, the textures will be updated from the copies data if they are dirty.

svn-id: r51234

1 files changed, 19 insertions, 38 deletions

diff --git a/backends/graphics/opengl/gltexture.cpp b/backends/graphics/opengl/gltexture.cpp
index 98291edfac..188386d0ab 100644
--- a/backends/graphics/opengl/gltexture.cpp
+++ b/backends/graphics/opengl/gltexture.cpp
@@ -56,18 +56,22 @@ static GLuint nextHigher2(GLuint v) {
 void GLTexture::initGLExtensions() {
 	static bool inited = false;
 
+	// Return if extensions already checked
 	if (inited)
 		return;
 
+	// Get a string with all extensions
 	const char* ext_string =
 		reinterpret_cast<const char*>(glGetString(GL_EXTENSIONS));
 	CHECK_GL_ERROR();
 	Common::StringTokenizer tokenizer(ext_string, " ");
+	// Iterate all string tokens
 	while (!tokenizer.empty()) {
 		Common::String token = tokenizer.nextToken();
 		if (token == "GL_ARB_texture_non_power_of_two")
 			npot_supported = true;
 	}
+
 	inited = true;
 }
 
@@ -83,31 +87,21 @@ GLTexture::GLTexture(byte bpp, GLenum format, GLenum type)
 	_refresh(false),
 	_filter(GL_NEAREST) {
 
-	// Generates the texture ID for GL
+	// Generate the texture ID
 	glGenTextures(1, &_textureName); CHECK_GL_ERROR();
-
-	// This all gets reset later in allocBuffer:
-	_surface.w = 0;
-	_surface.h = 0;
-	_surface.pitch = 0;
-	_surface.pixels = NULL;
-	_surface.bytesPerPixel = 0;
 }
 
 GLTexture::~GLTexture() {
+	// Delete the texture
 	glDeleteTextures(1, &_textureName); CHECK_GL_ERROR();
 }
 
 void GLTexture::refresh() {
-	// Generates the texture ID for GL
+	// Generate the texture ID
 	glGenTextures(1, &_textureName); CHECK_GL_ERROR();
 	_refresh = true;
 }
 
-void GLTexture::refreshBuffer() {
-	updateBuffer(_surface.pixels, _surface.pitch, 0, 0, _surface.w, _surface.h);
-}
-
 void GLTexture::allocBuffer(GLuint w, GLuint h) {
 	_realWidth = w;
 	_realHeight = h;
@@ -124,62 +118,47 @@ void GLTexture::allocBuffer(GLuint w, GLuint h) {
 		_textureHeight = nextHigher2(h);
 	}
 
-	// Allocate room for the texture now, but pixel data gets uploaded
-	// later (perhaps with multiple TexSubImage2D operations).
+	// Select this OpenGL texture
 	glBindTexture(GL_TEXTURE_2D, _textureName); CHECK_GL_ERROR();
+
+	// Set the texture parameters
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, _filter); CHECK_GL_ERROR();
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, _filter); CHECK_GL_ERROR();
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); CHECK_GL_ERROR();
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); CHECK_GL_ERROR();
+
+	// Allocate room for the texture
 	glTexImage2D(GL_TEXTURE_2D, 0, _glFormat,
 		     _textureWidth, _textureHeight, 0, _glFormat, _glType, NULL); CHECK_GL_ERROR();
 
-	if (_surface.w != _textureWidth || _surface.h != _textureHeight)
-		_surface.create(_textureWidth, _textureHeight, _bytesPerPixel);
-	else if (_refresh)
-		refreshBuffer();
-
 	_refresh = false;
 }
 
 void GLTexture::updateBuffer(const void *buf, int pitch, GLuint x, GLuint y, GLuint w, GLuint h) {
+	// Select this OpenGL texture
 	glBindTexture(GL_TEXTURE_2D, _textureName); CHECK_GL_ERROR();
 
+	// Check if the buffer has its data contiguously
 	if (static_cast<int>(w) * _bytesPerPixel == pitch) {
 		glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, w, h,
 						_glFormat, _glType, buf); CHECK_GL_ERROR();
-		if (buf != _surface.pixels)
-			memcpy(_surface.getBasePtr(x, y), buf, h * pitch);
 	} else {
+		// Update the texture row by row
 		const byte *src = static_cast<const byte *>(buf);
 		do {
 			glTexSubImage2D(GL_TEXTURE_2D, 0, x, y,
 							w, 1, _glFormat, _glType, src); CHECK_GL_ERROR();
-			if (buf != _surface.pixels)
-				memcpy(_surface.getBasePtr(x, y), src, w * _bytesPerPixel);
 			++y;
 			src += pitch;
 		} while (--h);
 	}
 }
 
-void GLTexture::fillBuffer(uint32 x) {
-	if (_bytesPerPixel == 1) 
-		memset(_surface.pixels, x, _surface.w * _surface.h);
-	else {
-		for (int i = 0; i < _surface.w * _surface.h; i++) {
-			memcpy(_surface.pixels, &x, _bytesPerPixel);
-		}
-	}
-
-	glBindTexture(GL_TEXTURE_2D, _textureName); CHECK_GL_ERROR();
-	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, _surface.w, _surface.h,
-		_glFormat, _glType, _surface.pixels);  CHECK_GL_ERROR();
-}
-
 void GLTexture::drawTexture(GLshort x, GLshort y, GLshort w, GLshort h) {
+	// Select this OpenGL texture
 	glBindTexture(GL_TEXTURE_2D, _textureName); CHECK_GL_ERROR();
 
+	// Calculate the texture rect that will be drawn
 	const GLfloat texWidth = (GLfloat)_realWidth / _textureWidth;//xdiv(_surface.w, _textureWidth);
 	const GLfloat texHeight = (GLfloat)_realHeight / _textureHeight;//xdiv(_surface.h, _textureHeight);
 	const GLfloat texcoords[] = {
@@ -190,6 +169,7 @@ void GLTexture::drawTexture(GLshort x, GLshort y, GLshort w, GLshort h) {
 	};
 	glTexCoordPointer(2, GL_FLOAT, 0, texcoords); CHECK_GL_ERROR();
 
+	// Calculate the screen rect where the texture will be drawn
 	const GLshort vertices[] = {
 		x,	   y,
 		x + w, y,
@@ -198,6 +178,7 @@ void GLTexture::drawTexture(GLshort x, GLshort y, GLshort w, GLshort h) {
 	};
 	glVertexPointer(2, GL_SHORT, 0, vertices); CHECK_GL_ERROR();
 
+	// Draw the texture to the screen buffer
 	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); CHECK_GL_ERROR();
 }