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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#ifndef VECTOR_RENDERER_H
#define VECTOR_RENDERER_H
#include "common/scummsys.h"
#include "graphics/surface.h"
namespace Graphics {
/**
* VectorRenderer: The core Vector Renderer Class
*
* This virtual class which exposes the API with all the vectorial
* rendering functions that may be used to draw on a given Surface.
*
* This class must be instantiated as one of its children, which implement
* the actual rendering functionality for each Byte Depth / Byte Format
* combination, and may also contain platform specific code.
*
* TODO: Expand documentation.
*
* @see VectorRendererSpec
* @see VectorRendererAA
*/
class VectorRenderer {
public:
/**
* Draws a line by considering the special cases for optimization.
*
* @param x1 Horizontal (X) coordinate for the line start
* @param x2 Horizontal (X) coordinate for the line end
* @param y1 Vertical (Y) coordinate for the line start
* @param y2 Vertical (Y) coordinate for the line end
*/
virtual void drawLine(int x1, int x2, int y1, int y2) = 0;
/**
* Gets the pixel pitch for the current drawing surface.
* Note: This is a real pixel-pitch, not a byte-pitch.
* That means it can be safely used in pointer arithmetics and
* in pixel manipulation.
*
* @return integer with the active bytes per pixel
*/
virtual uint16 surfacePitch() {
return _activeSurface->pitch / _activeSurface->bytesPerPixel;
}
/**
* Gets the BYTES (not bits) per Pixel we are working on,
* based on the active drawing surface.
*
* @return integer byte with the active bytes per pixel value
*/
virtual uint8 bytesPerPixel() {
return _activeSurface->bytesPerPixel;
}
/**
* Set the active painting color for the renderer.
* All the drawing from then on will be done with that color, unless
* specified otherwise.
*
* @param r value of the red color byte
* @param g value of the green color byte
* @param b value of the blue color byte
*/
virtual void setColor(uint8 r, uint8 g, uint8 b) = 0;
/**
* Set the active painting color for the renderer, including alpha
* intensity. All the drawing from then on will be done with that color,
* unless specified otherwise.
*
* @param r value of the red color byte
* @param g value of the green color byte
* @param b value of the blue color byte
* @param a value of the alpha byte
*/
virtual void setColor(uint8 r, uint8 g, uint8 b, uint8 a) = 0;
protected:
/**
* Generic line drawing algorithm. May be implemented by each
* inheriting class, i.e. with platform specific code.
*
* @see VectorRenderer::drawLine()
* @param x1 Horizontal (X) coordinate for the line start
* @param x2 Horizontal (X) coordinate for the line end
* @param y1 Vertical (Y) coordinate for the line start
* @param y2 Vertical (Y) coordinate for the line end
* @param dx Horizontal (X) increasement.
* @param dy Vertical (Y) increasement.
*/
virtual void drawLineAlg(int x1, int x2, int y1, int y2, int dx, int dy) = 0;
virtual void drawCircleAlg(int x, int y, int r) = 0;
Surface *_activeSurface; /** Pointer to the surface currently being drawn */
};
/**
* VectorRendererSpec: Specialized Vector Renderer Class
*
* This templated class implements the basic subset of vector operations for
* all platforms by allowing the user to provide the actual Pixel Type and
* pixel information structs.
*
* This class takes two template parameters:
*
* @param PixelType Defines a type which may hold the color value of a single
* pixel, such as "byte" or "uint16" for 8 and 16 BPP respectively.
*
* @param PixelFormat Defines the type of the PixelFormat struct which contains all
* the actual information of the pixels being used, as declared in "graphics/colormasks.h"
*
* TODO: Expand documentation.
*
* @see VectorRenderer
*/
template<typename PixelType, typename PixelFormat>
class VectorRendererSpec : public VectorRenderer {
/**
* @see VectorRenderer::drawLine()
*/
void drawLine(int x1, int x2, int y1, int y2);
/**
* @see VectorRenderer::setColor()
*/
void setColor(uint8 r, uint8 g, uint8 b, uint8 a) {
_color = ARGBToColor<PixelFormat>(r, g, b, a);
}
/**
* @see VectorRenderer::setColor()
*/
void setColor(uint8 r, uint8 g, uint8 b) {
_color = RGBToColor<PixelFormat>(r, g, b);
}
protected:
/*
* "Bresenham's Line Algorithm", as described in Wikipedia.
* Based on the current implementation in "graphics/primitives.cpp".
*
* Generic line drawing algorithm for the aliased renderer. Optimized with no
* floating point operations and direct access to pixel buffer, assumes no special cases.
*
* @see VectorRenderer::drawLineAlg()
*/
virtual void drawLineAlg(int x1, int x2, int y1, int y2, int dx, int dy);
virtual void drawCircleAlg(int x, int y, int r) {}
PixelType _color; /** Color currently being used to draw on the renderer */
};
/**
* VectorRendererAA: Anti-Aliased Vector Renderer Class
*
* This templated class inherits all the functionality of the VectorRendererSpec
* class but uses better looking yet slightly slower AA algorithms for drawing
* most primivitves. May be used in faster platforms.
*
* TODO: Expand documentation.
*
* @see VectorRenderer
* @see VectorRendererSpec
*/
template<typename PixelType, typename PixelFormat>
class VectorRendererAA : public VectorRendererSpec<PixelType,PixelFormat> {
protected:
/**
* "Wu's Line Antialiasing Algorithm" as published by Xiaolin Wu, July 1991
* Based on the implementation found in Michael Abrash's Graphics Programming Black Book.
*
* Generic line drawing algorithm for the Antialiased renderer. Optimized with no
* floating point operations, assumes no special cases.
*
* @see VectorRenderer::drawLineAlg()
*/
void drawLineAlg(int x1, int x2, int y1, int y2, int dx, int dy);
/**
* Calculates the blending weight (relative luminosity) value for
* a given pixel, based on the distance to the ideal line.
* Used for blending pixels in the Wu AA algorithm.
*
* @param line_color Byte value of a color component (R/G/B) of the color used to draw the line.
* @param line_color Byte value of a color component (R/G/B) of the color used to draw the BG.
* @param weight Weight of the pixel as calculated by Wu's algorithm.
* @return The new color value for the given component.
*/
inline uint8 antialiasingBlendWeight(uint8 line_color, uint8 bg_color, uint weight) {
uint8 value;
if (bg_color > line_color) {
value = weight / 255 * (bg_color - line_color) + bg_color;
} else {
value = weight / 255 * (line_color - bg_color) + line_color;
}
return value;
}
};
} // end of namespace Graphics
#endif
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