scummvm/engines/agi/picture_gal.cpp
2025-01-05 09:49:27 +02:00

267 lines
6.9 KiB
C++

/* 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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
#include "agi/agi.h"
#include "agi/graphics.h"
#include "agi/picture.h"
#include "agi/picture_gal.h"
namespace Agi {
// PictureMgr_GAL decodes and draws picture resources in early King's Quest 1.
//
// This "Game Adaptation Language" format was used in PC Booters and Apple II.
//
// This format supports lines and flood fills, and visual and priority screens.
//
// As this is the format that evolved into AGI, it is quite similar apart from
// the specific opcodes. The major difference is the line drawing routine;
// it produces different results than AGI. Flood fills implicitly rely on this.
// When KQ1 was ported to AGI, the new lines prevented some fills from working,
// so they just added more. There are still a few white pixels they missed.
//
// As with Troll's Tale, room pictures depend on the game first drawing a frame
// within the entire picture area. When KQ1 was converted to AGI, this frame
// was added to each individual picture resource.
PictureMgr_GAL::PictureMgr_GAL(AgiBase *agi, GfxMgr *gfx) :
PictureMgr(agi, gfx) {
}
void PictureMgr_GAL::drawPicture() {
debugC(kDebugLevelPictures, "Drawing picture %d", _resourceNr);
drawBlackFrame();
_dataOffset = 0;
_dataOffsetNibble = false;
_patCode = 0;
_patNum = 0;
_priOn = true; // initially off in AGI
_scrOn = false;
_scrColor = 15;
_priColor = 1;
// GAL toggles the current screen between visual and priority
// with opcode F0. This affects opcodes F4-F7, but the rest of
// the opcodes are explicit about which screen(s) they draw to.
byte prevScrOn = _scrOn;
byte prevPriOn = _priOn;
while (_dataOffset < _dataSize) {
byte curByte = getNextByte();
switch (curByte) {
case 0xf0: // toggle current screen
draw_SetScreens(!_scrOn, !_priOn);
break;
case 0xf1:
draw_SetColor();
break;
case 0xf2:
draw_SetPriority();
break;
case 0xf3:
draw_SetColor();
draw_SetPriority();
break;
// Line operations drawn to both visual and priority screens
case 0xf4:
draw_SetScreens(true, true, prevScrOn, prevPriOn);
yCorner();
draw_SetScreens(prevScrOn, prevPriOn);
break;
case 0xf5:
draw_SetScreens(true, true, prevScrOn, prevPriOn);
xCorner();
draw_SetScreens(prevScrOn, prevPriOn);
break;
case 0xf6:
draw_SetScreens(true, true, prevScrOn, prevPriOn);
draw_LineAbsolute();
draw_SetScreens(prevScrOn, prevPriOn);
break;
case 0xf7:
draw_SetScreens(true, true, prevScrOn, prevPriOn);
draw_LineShort();
draw_SetScreens(prevScrOn, prevPriOn);
break;
// Line operations drawn to the current screen
case 0xf8:
yCorner();
break;
case 0xf9:
xCorner();
break;
case 0xfa:
draw_LineAbsolute();
break;
case 0xfb:
draw_LineShort();
break;
// Fill operations drawn to one or both screens
case 0xfc:
draw_SetScreens(true, true, prevScrOn, prevPriOn);
draw_SetColor();
draw_SetPriority();
draw_Fill();
draw_SetScreens(prevScrOn, prevPriOn);
break;
case 0xfd:
draw_SetScreens(false, true, prevScrOn, prevPriOn);
draw_SetPriority();
draw_Fill();
draw_SetScreens(prevScrOn, prevPriOn);
break;
case 0xfe:
draw_SetScreens(true, false, prevScrOn, prevPriOn);
draw_SetColor();
draw_Fill();
draw_SetScreens(prevScrOn, prevPriOn);
break;
case 0xff: // end of data
return;
default:
warning("Unknown picture opcode %02x at %04x", curByte, _dataOffset - 1);
break;
}
}
}
/**
* Sets the status of the visual and priority screens.
*/
void PictureMgr_GAL::draw_SetScreens(byte scrOn, byte priOn) {
_scrOn = scrOn;
_priOn = priOn;
}
/**
* Sets the status of the visual and priority screens,
* and returns their previous values.
*/
void PictureMgr_GAL::draw_SetScreens(byte scrOn, byte priOn, byte &prevScrOn, byte &prevPriOn) {
prevScrOn = _scrOn;
prevPriOn = _priOn;
_scrOn = scrOn;
_priOn = priOn;
}
/**
* Draws a hard-coded black frame in both screens.
* All room pictures require this to draw correctly.
*
* Original data: F3 00 00 F5 00 00 9F A7 00 00 FF
*/
void PictureMgr_GAL::drawBlackFrame() {
_scrOn = true;
_scrColor = 0;
_priOn = true;
_priColor = 0;
draw_Line(0, 0, _width - 1, 0);
draw_Line(_width - 1, 0, _width - 1, _height - 1);
draw_Line(_width - 1, _height - 1, 0, _height - 1);
draw_Line(0, _height - 1, 0, 0);
}
/**
* Draws a horizontal, vertical, or diagonal line using the GAL drawing routine.
*
* This routine produces different diagonal lines than the AGI routine.
*/
void PictureMgr_GAL::draw_Line(int16 x1, int16 y1, int16 x2, int16 y2) {
x1 = CLIP<int16>(x1, 0, _width - 1);
x2 = CLIP<int16>(x2, 0, _width - 1);
y1 = CLIP<int16>(y1, 0, _height - 1);
y2 = CLIP<int16>(y2, 0, _height - 1);
const byte width = (x2 > x1) ? (x2 - x1) : (x1 - x2);
const byte height = (y2 > y1) ? (y2 - y1) : (y1 - y2);
byte x = 0;
byte y = 0;
if (width > height) {
while (x != width) {
x++;
y = (x * height) / width;
if (((x * height) % width) * 2 > width) {
y++;
}
byte pixelX = (x2 > x1) ? (x1 + x) : (x1 - x);
byte pixelY = (y2 > y1) ? (y1 + y) : (y1 - y);
putVirtPixel(pixelX, pixelY);
}
} else {
while (y != height) {
y++;
x = (y * width) / height;
if (((y * width) % height) * 2 > height) {
x++;
}
byte pixelX = (x2 > x1) ? (x1 + x) : (x1 - x);
byte pixelY = (y2 > y1) ? (y1 + y) : (y1 - y);
putVirtPixel(pixelX, pixelY);
}
}
}
/**
* Gets the next x coordinate in the current picture instruction,
* and clip it to the picture width.
*/
bool PictureMgr_GAL::getNextXCoordinate(byte &x) {
if (!getNextParamByte(x)) {
return false;
}
if (x >= _width) { // 160
debugC(kDebugLevelPictures, "clipping %c from %d to %d", 'x', x, _width - 1);
x = _width - 1; // 159
}
return true;
}
/**
* Gets the next y coordinate in the current picture instruction,
* and clip it to the picture height.
*/
bool PictureMgr_GAL::getNextYCoordinate(byte &y) {
if (!getNextParamByte(y)) {
return false;
}
if (y >= _height) { // 168
debugC(kDebugLevelPictures, "clipping %c from %d to %d", 'y', y, _height);
y = _height - 1; // 167
}
return true;
}
} // End of namespace Agi