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Backdrop.cpp
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Backdrop.cpp
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/**************************************************************************
Backdrop.cpp - Functions for manipulating backdrop
**************************************************************************/
/* ============= */
/* Include files */
/* ============= */
#include "dxstdafx.h"
#include "StuntCarRacer.h"
#include "Backdrop.h"
#include "3D_Engine.h"
/* ===== */
/* Debug */
/* ===== */
#if defined(DEBUG) || defined(_DEBUG)
extern FILE *out;
#endif
/* ========= */
/* Constants */
/* ========= */
#define SKY_COLOUR (SCR_BASE_COLOUR + 7)
#define GROUND_COLOUR (SCR_BASE_COLOUR + 13)
// Scenery type ranges 0-4
#define MIN_SCENERY_TYPE 0
#define MAX_SCENERY_TYPE 4
/* =========== */
/* Static data */
/* =========== */
static long current_scenery_type = MAX_SCENERY_TYPE;
/* ===================== */
/* Function declarations */
/* ===================== */
static void DrawHorizon( long viewpoint_y,
long viewpoint_x_angle,
long viewpoint_z_angle );
static void DrawScenery( long viewpoint_y,
long viewpoint_x_angle,
long viewpoint_y_angle,
long viewpoint_z_angle );
static long ClipLine( long *x1ptr,
long *y1ptr,
long *x2ptr,
long *y2ptr,
long screen_width,
long screen_height );
/* ======================================================================================= */
/* Function: DrawBackdrop */
/* */
/* Description: Draw the backdrop using the supplied viewpoint */
/* ======================================================================================= */
void DrawBackdrop( long viewpoint_y,
long viewpoint_x_angle,
long viewpoint_y_angle,
long viewpoint_z_angle )
{
DrawHorizon(viewpoint_y,
viewpoint_x_angle,
viewpoint_z_angle);
DrawScenery(viewpoint_y,
viewpoint_x_angle,
viewpoint_y_angle,
viewpoint_z_angle);
}
/* ======================================================================================= */
/* Function: NextSceneryType */
/* */
/* Description: Change to the next type of scenery */
/* ======================================================================================= */
void NextSceneryType( void )
{
current_scenery_type++;
if (current_scenery_type > MAX_SCENERY_TYPE)
current_scenery_type = MIN_SCENERY_TYPE;
}
/* ======================================================================================= */
/* Function: DrawHorizon */
/* */
/* Description: Draw the horizon using the supplied viewpoint */
/* - fills the entire screen with ground/sky colours */
/* ======================================================================================= */
// should only be able to see as far as horizon,
// so if track is further away then either :-
//
// horizon should also be further away
// OR
// shouldn't be drawing pieces at this distance
//
// - viewpoint limitations should eventually prevent track exceeding horizon
static void DrawHorizon( long viewpoint_y,
long viewpoint_x_angle,
long viewpoint_z_angle )
{
long i;
long upside_down = FALSE;
short sin_x, sin_z;
short cos_x, cos_z;
long x, y, z, y_adjust;
long trans_x, trans_y, trans_z;
long screen_width, screen_height;
long x1, y1, x2, y2, xs, xl, ys, yl;
// set up two co-ordinates defining horizon line
COORD_3D plane[2];
COORD_2D screen_coords[2];
// left co-ordinate
plane[0].x = -0x00010000;
plane[0].y = 0;
plane[0].z = 0x00010000;
// right co-ordinate
plane[1].x = 0x00010000;
plane[1].y = 0;
plane[1].z = 0x00010000;
// start of code
GetScreenDimensions(&screen_width, &screen_height);
// calculate y adjustment depending upon viewpoint_x_angle.
// this is needed because only two horizon points are used rather than four.
// when the rotated z values are negative (i.e. viewpoint_x_angle in range shown)
// the resulting y values are negated so the y adjustment must also change sign
if ((viewpoint_x_angle >= (MAX_ANGLE/4)) &&
(viewpoint_x_angle < ((3*MAX_ANGLE)/4))) // if >= 90 and less than 270 degrees
y_adjust = (viewpoint_y >> LOG_PRECISION);
else
y_adjust = -(viewpoint_y >> LOG_PRECISION);
y_adjust /= 2; // 24/04/1998 - reduce using PC_FACTOR
// rotate two points about x/z axis and perform perspective projection
GetSinCos(viewpoint_x_angle, &sin_x, &cos_x);
GetSinCos(viewpoint_z_angle, &sin_z, &cos_z);
for (i = 0; i < 2; i++)
{
x = plane[i].x;
y = plane[i].y;
z = plane[i].z;
y += y_adjust;
// rotate about x axis
trans_y = (y * cos_x) - (z * sin_x);
trans_z = (y * sin_x) + (z * cos_x);
// rotate about z axis
y = trans_y >> LOG_PRECISION;
trans_x = (x * cos_z) - (y * sin_z);
trans_y = (x * sin_z) + (y * cos_z);
// perspective projection
z = trans_z >> LOG_FOCUS;
// debug stuff
if (z == 0)
{
#if defined(DEBUG) || defined(_DEBUG)
fprintf(out, "7. Preventing division by zero\n");
//Sleep(10);
#endif
z = 1;
}
x = (trans_x / z) + screen_width/2;
y = (trans_y / z) + screen_height/2;
// store screen x and screen y
screen_coords[i].x = x;
screen_coords[i].y = y;
}
x1 = screen_coords[0].x; y1 = screen_coords[0].y;
x2 = screen_coords[1].x; y2 = screen_coords[1].y;
//fprintf(out, "(x1,y1) = (%d,%d), (x2,y2) = (%d,%d)\n", x1, y1, x2, y2);
// draw required rectangular sections
long min_x = 0;
long min_y = 0;
long max_x = screen_width - 1;
long max_y = screen_height - 1;
long on_screen, draw, ytop = 0, ybottom = 0, colour_index = 0;
if ((x1 > x2) || ((x1 == x2) && (y1 > y2)))
upside_down = (! upside_down);
on_screen = ClipLine(&x1, &y1, &x2, &y2, screen_width, screen_height);
//fprintf(out, "upside_down = %d, on_screen = %d\n", upside_down, on_screen);
//fprintf(out, "clipped (x1,y1) = (%d,%d), (x2,y2) = (%d,%d)\n\n", x1, y1, x2, y2);
// get smallest and largest y
if (y2 < y1)
{
xs = x2;
ys = y2;
xl = x1;
yl = y1;
}
else
{
xs = x1;
ys = y1;
xl = x2;
yl = y2;
}
// special check for when line has been clipped to a single
// pixel (i.e. one of the four corners of the screen)
if ((xs == xl) && (ys == yl))
on_screen = FALSE;
if (on_screen)
{
// draw top rectangle
draw = FALSE;
if (! upside_down)
{
colour_index = SKY_COLOUR;
if (ys != yl)
{
ytop = 0;
if ((xl > min_x) && (xl < max_x)) // if not at either edge
ybottom = yl;
else
ybottom = yl - 1;
draw = TRUE;
}
else // ys == yl
if (ys > 0)
{
ytop = 0;
if (((xs == min_x) && (xl == max_x)) ||
((xs == max_x) && (xl == min_x))) // if at both edges
ybottom = ys - 1;
else
ybottom = ys;
draw = TRUE;
}
}
else // upside down
{
colour_index = GROUND_COLOUR;
if (ys != yl)
{
if (ys > 0)
{
ytop = 0;
ybottom = ys - 1;
draw = TRUE;
}
}
else // ys == yl
{
if (((xs == min_x) && (xl == max_x)) ||
((xs == max_x) && (xl == min_x))) // if at both edges
{
ytop = 0;
ybottom = ys;
draw = TRUE;
}
}
}
if (draw)
{
DrawFilledRectangle(min_x, ytop, max_x, ybottom, SCRGB(colour_index));
}
// draw bottom rectangle
// simply fill the area that the above rectangle missed
if (colour_index == SKY_COLOUR)
colour_index = GROUND_COLOUR;
else
colour_index = SKY_COLOUR;
if (draw) // if previous rectangle was drawn
{
if (ybottom < max_y)
{
DrawFilledRectangle(min_x, ybottom+1, max_x, max_y, SCRGB(colour_index));
}
}
else
{
DrawFilledRectangle(min_x, min_y, max_x, max_y, SCRGB(colour_index));
}
}
else // horizon line is off screen
{
long off_top = FALSE, off_bottom = FALSE;
long off_left = FALSE, off_right = FALSE;
if ((y1 <= min_y) && (y2 <= min_y))
off_top = TRUE;
if ((y1 >= max_y) && (y2 >= max_y))
off_bottom = TRUE;
if ((x1 <= min_x) && (x2 <= min_x))
off_left = TRUE;
if ((x1 >= max_x) && (x2 >= max_x))
off_right = TRUE;
if (off_top)
{
if (! upside_down)
colour_index = GROUND_COLOUR;
else
colour_index = SKY_COLOUR;
}
else if (off_bottom)
{
if (! upside_down)
colour_index = SKY_COLOUR;
else
colour_index = GROUND_COLOUR;
}
else if (off_left)
{
if (y1 > y2)
colour_index = GROUND_COLOUR;
else
colour_index = SKY_COLOUR;
}
else if (off_right)
{
if (y1 > y2)
colour_index = SKY_COLOUR;
else
colour_index = GROUND_COLOUR;
}
DrawFilledRectangle(min_x, min_y, max_x, max_y, SCRGB(colour_index));
}
// draw sloping ground section
if ((on_screen) && (y1 != y2))
{
long sides = 0;
POINT points[MAX_POLY_SIDES];
if (y1 < y2)
{
// ground on left area of screen
// 17/02/1999 - add one to y2 because Direct3D doesn't include last pixel
// (D3DRENDERSTATE_LASTPIXEL doesn't seem to have any effect)
++y2;
if (x1 > min_x)
{
points[sides].x = min_x; points[sides].y = y1; sides++;
}
points[sides].x = x1; points[sides].y = y1; sides++;
points[sides].x = x2; points[sides].y = y2; sides++;
if (x2 > min_x)
{
points[sides].x = min_x; points[sides].y = y2; sides++;
}
}
else
{
// ground on right area of screen
// 17/02/1999 - add one to y1, max_x because Direct3D doesn't include last pixel
// (D3DRENDERSTATE_LASTPIXEL doesn't seem to have any effect)
++y1;
++max_x;
if (x1 < max_x)
{
points[sides].x = max_x; points[sides].y = y1; sides++;
}
points[sides].x = x1; points[sides].y = y1; sides++;
points[sides].x = x2; points[sides].y = y2; sides++;
if (x2 < max_x)
{
points[sides].x = max_x; points[sides].y = y2; sides++;
}
}
SetTextureColour(GROUND_COLOUR);
if (sides >= 3)
DrawPolygon(points, sides);
}
}
/* ======================================================================================= */
/* Function: DrawScenery */
/* */
/* Description: Draw the current scenery using the supplied viewpoint */
/* ======================================================================================= */
#define NUM_SCENERY_OBJECTS 32
#define MAX_SCENERY_COORDS 7
#define SCENERY_X_Y_SCALE_FACTOR 64 // (z of 0x00010000, divided by (4 * FOCUS))
typedef struct
{
COORD_3D *coords;
long coordsSize; // memory size for coords
long numPolygons;
long *polygons;
} SCENERY;
static void DrawScenery( long viewpoint_y,
long viewpoint_x_angle,
long viewpoint_y_angle,
long viewpoint_z_angle )
{
// scenery y positions (range 0-255)
static long scenery_positions[NUM_SCENERY_OBJECTS] =
{0x05,0x0f,0x15,0x1f,0x25,0x2f,0x35,0x3f,
0x45,0x4f,0x55,0x5f,0x65,0x6f,0x75,0x7f,
0x85,0x8f,0x95,0x9f,0xa5,0xaf,0xb5,0xbf,
0xc5,0xcf,0xd5,0xdf,0xe5,0xef,0xf5,0xff};
// scenery numbers (i.e. IDs, range 0-24)
static long standard_numbers[NUM_SCENERY_OBJECTS] =
{0,13,10,11,12,5,2,3,
0,1,4,5,2,1,0,5,
2,3,4,5,0,9,6,7,
8,5,0,3,4,1,2,5};
static long taller_numbers[NUM_SCENERY_OBJECTS] =
{14,15,15,14,15,14,14,15,
14,15,14,15,15,14,15,14,
14,15,15,14,15,15,14,14,
15,14,15,15,14,14,14,15};
static long snowcapped_numbers[NUM_SCENERY_OBJECTS] =
{16,17,18,19,17,16,17,18,
18,16,19,17,19,18,18,16,
19,17,17,18,16,16,19,18,
17,16,19,19,17,18,16,19};
static long building_numbers[NUM_SCENERY_OBJECTS] =
{20,21,22,23,23,21,20,20,
21,22,22,20,20,21,23,22,
21,20,21,21,23,22,20,21,
23,23,22,20,21,20,21,23};
static long mixed_numbers[NUM_SCENERY_OBJECTS] =
{16,0,18,1,17,2,17,3,
18,4,19,5,20,24,21,24,
23,22,12,19,6,16,7,18,
8,16,9,19,10,18,11,19};
static long *scenery_types[] =
{standard_numbers,
taller_numbers,
snowcapped_numbers,
building_numbers,
mixed_numbers};
long *scenery_numbers = scenery_types[current_scenery_type];
// scenery co-ordinates
static COORD_3D standard1_c[] =
{{0,0,0x00010000}, // x, y, z
{0x180,0,0x00010000},
{0x4b,0x1c,0x00010000},
{0x104,0x10,0x00010000}};
static COORD_3D standard2_c[] =
{{0,0,0x00010000},
{0x100,0,0x00010000},
{0x7d,0x12,0x00010000},
{0xc0,0x1e,0x00010000}};
static COORD_3D standard3_c[] =
{{0,0,0x00010000},
{0x180,0,0x00010000},
{0x64,0x14,0x00010000},
{0x136,0x25,0x00010000}};
static COORD_3D standard4_c[] =
{{0,0,0x00010000},
{0x100,0,0x00010000},
{0x46,0x18,0x00010000},
{0xd8,0x24,0x00010000}};
static COORD_3D standard5_c[] =
{{0,0,0x00010000},
{0x180,0,0x00010000},
{0xc8,0x27,0x00010000},
{0xf0,0x1f,0x00010000}};
static COORD_3D standard6_c[] =
{{0,0,0x00010000},
{0x100,0,0x00010000},
{0x32,0xc,0x00010000},
{0xa8,0x1a,0x00010000}};
static COORD_3D standard7_c[] =
{{0,0,0x00010000},
{0x172,0,0x00010000},
{0x70,0x19,0x00010000},
{0xe6,0x14,0x00010000}};
static COORD_3D standard8_c[] =
{{0,0,0x00010000},
{0xfa,0,0x00010000},
{0x64,0xc,0x00010000},
{0xbb,0x12,0x00010000}};
static COORD_3D standard9_c[] =
{{0,0,0x00010000},
{0x180,0,0x00010000},
{0xc6,0x1c,0x00010000},
{0x13b,0x18,0x00010000}};
static COORD_3D standard10_c[] =
{{0,0,0x00010000},
{0x100,0,0x00010000},
{0x23,0x28,0x00010000},
{0x6e,0x37,0x00010000}};
static COORD_3D standard11_c[] =
{{0,0,0x00010000},
{0x159,0,0x00010000},
{0x5c,0x2a,0x00010000},
{0xf0,0x1e,0x00010000}};
static COORD_3D standard12_c[] =
{{0,0,0x00010000},
{0xfa,0,0x00010000},
{0x2d,0xf,0x00010000},
{0x80,0xb,0x00010000}};
static COORD_3D standard13_c[] =
{{0,0,0x00010000},
{0x17c,0,0x00010000},
{0x88,0x2b,0x00010000},
{0xd2,0x23,0x00010000}};
static COORD_3D standard14_c[] =
{{0,0,0x00010000},
{0x100,0,0x00010000},
{0x4b,0x29,0x00010000},
{0x9b,0x37,0x00010000}};
static COORD_3D taller1_c[] =
{{0,0,0x00010000},
{0x17c,0,0x00010000},
{0x88,0,0x00010000},
{0x2b,0xd2,0x00010000}};
static COORD_3D taller2_c[] =
{{0,0,0x00010000},
{0x100,0,0x00010000},
{0x4b,0,0x00010000},
{0x29,0x9b,0x00010000}};
static COORD_3D snowcapped1_c[] =
{{0,0,0x00010000},
{0xfa,0,0x00010000},
{0x1a4,0,0x00010000},
{0x253,0,0x00010000},
{0x181,0x2e,0x00010000},
{0x118,0x34,0x00010000},
{0x19f,0x73,0x00010000}};
static COORD_3D snowcapped2_c[] =
{{0,0,0x00010000},
{0x4b,0,0x00010000},
{0x127,0,0x00010000},
{0x1f4,0,0x00010000},
{0xaf,0x32,0x00010000},
{0x87,0x3c,0x00010000},
{0xff,0x48,0x00010000}};
static COORD_3D snowcapped3_c[] =
{{0,0,0x00010000},
{0x87,0,0x00010000},
{0xc5,0,0x00010000},
{0xfa,0,0x00010000},
{0x96,0x46,0x00010000},
{0x69,0x50,0x00010000},
{0xaa,0x5f,0x00010000}};
static COORD_3D snowcapped4_c[] =
{{0,0,0x00010000},
{0x87,0,0x00010000},
{0x113,0,0x00010000},
{0x1a9,0,0x00010000},
{0x91,0x2a,0x00010000},
{0x3c,0x32,0x00010000},
{0x8c,0x4d,0x00010000}};
static COORD_3D building1_c[] =
{{0,0,0x00010000},
{0x10,0,0x00010000},
{0x18,0,0x00010000},
{0,0x50,0x00010000},
{0x10,0x50,0x00010000},
{0x18,0x50,0x00010000}};
static COORD_3D building2_c[] =
{{0,0,0x00010000},
{0x10,0,0x00010000},
{0x18,0,0x00010000},
{0,0x3c,0x00010000},
{0x10,0x3c,0x00010000},
{0x18,0x3c,0x00010000}};
static COORD_3D building3_c[] =
{{0,0,0x00010000},
{0x28,0,0x00010000},
{0x3c,0,0x00010000},
{0,0x39,0x00010000},
{0x28,0x39,0x00010000},
{0x3c,0x39,0x00010000}};
static COORD_3D building4_c[] =
{{0,0,0x00010000},
{0x69,0,0x00010000},
{0x7d,0,0x00010000},
{0,0x2a,0x00010000},
{0x69,0x2a,0x00010000},
{0x7d,0x2a,0x00010000}};
static COORD_3D lake_c[] =
{{0,8,0x00010000},
{0x32,0,0x00010000},
{0x28a,0x0,0x00010000},
{0x2bc,8,0x00010000}};
// scenery polygons
static long standard_p[] =
{5, // colour
4, // number of sides
1, 0, 2, 3}; // co-ordinate offsets
static long taller_p[] =
{4,
3,
2, 0, 3,
5,
3,
1, 2, 3};
static long snowcapped_p[] =
{4,
4,
1, 0, 5, 4,
5,
3,
2, 1, 4,
5,
4,
3, 2, 4, 6,
15,
3,
4, 5, 6};
static long building_p[] =
{15,
4,
1, 0, 3, 4,
14,
4,
2, 1, 4, 5};
static long lake_p[] =
{6,
4,
2, 1, 0, 3};
// scenery definitions
static SCENERY standard1 = {standard1_c, sizeof(standard1_c), 1, standard_p};
static SCENERY standard2 = {standard2_c, sizeof(standard2_c), 1, standard_p};
static SCENERY standard3 = {standard3_c, sizeof(standard3_c), 1, standard_p};
static SCENERY standard4 = {standard4_c, sizeof(standard4_c), 1, standard_p};
static SCENERY standard5 = {standard5_c, sizeof(standard5_c), 1, standard_p};
static SCENERY standard6 = {standard6_c, sizeof(standard6_c), 1, standard_p};
static SCENERY standard7 = {standard7_c, sizeof(standard7_c), 1, standard_p};
static SCENERY standard8 = {standard8_c, sizeof(standard8_c), 1, standard_p};
static SCENERY standard9 = {standard9_c, sizeof(standard9_c), 1, standard_p};
static SCENERY standard10 = {standard10_c, sizeof(standard10_c), 1, standard_p};
static SCENERY standard11 = {standard11_c, sizeof(standard11_c), 1, standard_p};
static SCENERY standard12 = {standard12_c, sizeof(standard12_c), 1, standard_p};
static SCENERY standard13 = {standard13_c, sizeof(standard13_c), 1, standard_p};
static SCENERY standard14 = {standard14_c, sizeof(standard14_c), 1, standard_p};
static SCENERY taller1 = {taller1_c, sizeof(taller1_c), 2, taller_p};
static SCENERY taller2 = {taller2_c, sizeof(taller2_c), 2, taller_p};
static SCENERY snowcapped1 = {snowcapped1_c, sizeof(snowcapped1_c), 4, snowcapped_p};
static SCENERY snowcapped2 = {snowcapped2_c, sizeof(snowcapped2_c), 4, snowcapped_p};
static SCENERY snowcapped3 = {snowcapped3_c, sizeof(snowcapped3_c), 4, snowcapped_p};
static SCENERY snowcapped4 = {snowcapped4_c, sizeof(snowcapped4_c), 4, snowcapped_p};
static SCENERY building1 = {building1_c, sizeof(building1_c), 2, building_p};
static SCENERY building2 = {building2_c, sizeof(building2_c), 2, building_p};
static SCENERY building3 = {building3_c, sizeof(building3_c), 2, building_p};
static SCENERY building4 = {building4_c, sizeof(building4_c), 2, building_p};
static SCENERY lake = {lake_c, sizeof(lake_c), 1, lake_p};
static SCENERY *scenery_objects[NUM_SCENERY_OBJECTS] =
{
&standard1,
&standard2,
&standard3,
&standard4,
&standard5,
&standard6,
&standard7,
&standard8,
&standard9,
&standard10,
&standard11,
&standard12,
&standard13,
&standard14,
&taller1,
&taller2,
&snowcapped1,
&snowcapped2,
&snowcapped3,
&snowcapped4,
&building1,
&building2,
&building3,
&building4,
&lake
};
SCENERY *scenery;
COORD_3D *scenery_coords;
COORD_2D screen_coords[MAX_SCENERY_COORDS];
long m, i, j, number, sides, offset;
long position, y_angle, visible;
short sin_x, sin_y, sin_z;
short cos_x, cos_y, cos_z;
long x, y, z;
long trans_x, trans_y, trans_z;
long screen_width, screen_height;
long *polygons;
BYTE colour;
POINT points[MAX_POLY_SIDES];
// start of code
GetScreenDimensions(&screen_width, &screen_height);
// x/z angle are fixed for all scenery objects
GetSinCos(viewpoint_x_angle, &sin_x, &cos_x);
GetSinCos(viewpoint_z_angle, &sin_z, &cos_z);
for (m = 0; m < NUM_SCENERY_OBJECTS; m++)
{
// get pointer to scenery definition
number = scenery_numbers[m];
scenery = scenery_objects[number];
// get pointer to scenery co-ordinates
scenery_coords = scenery->coords;
// calculate number of co-ordinates
number = scenery->coordsSize / sizeof(COORD_3D);
// calculate y angle for this scenery object
position = scenery_positions[m] * 256;
y_angle = viewpoint_y_angle + position;
y_angle &= (MAX_ANGLE - 1);
// 29/06/1998 - temporarily reverse y_angle
y_angle = (-y_angle & (MAX_ANGLE - 1));
GetSinCos(y_angle, &sin_y, &cos_y);
// rotate scenery about x/y/z axis and perform perspective projection
visible = TRUE;
for (i = 0; i < number; i++)
{
x = scenery_coords[i].x * SCENERY_X_Y_SCALE_FACTOR;
y = -(scenery_coords[i].y * SCENERY_X_Y_SCALE_FACTOR);
z = scenery_coords[i].z;
y -= ((viewpoint_y / 2) >> LOG_PRECISION); // 24/04/1998 - reduce using PC_FACTOR
// prevent sky showing through between scenery and ground
y += (2 * SCENERY_X_Y_SCALE_FACTOR);
// rotate about y axis
trans_x = (x * cos_y) + (z * sin_y);
trans_z = (z * cos_y) - (x * sin_y);
// rotate about x axis
z = trans_z >> LOG_PRECISION;
trans_y = (y * cos_x) - (z * sin_x);
trans_z = (y * sin_x) + (z * cos_x);
// rotate about z axis
x = trans_x >> LOG_PRECISION;
y = trans_y >> LOG_PRECISION;
trans_x = (x * cos_z) - (y * sin_z);
trans_y = (x * sin_z) + (y * cos_z);
// skip this scenery object if any z negative (i.e. infront of screen)
if (trans_z <= 0)
{
visible = FALSE;
break;
}
// could also eliminate scenery if selected points are outside the
// viewing pyramid, although the saving would probably be negligible
// perspective projection
z = trans_z >> LOG_FOCUS;
// debug stuff
if (z == 0)
{
#if defined(DEBUG) || defined(_DEBUG)
fprintf(out, "8. Preventing division by zero\n");
//Sleep(10);
#endif
z = 1;
}
x = (trans_x / z) + screen_width/2;
y = (trans_y / z) + screen_height/2;
// store screen x and screen y
screen_coords[i].x = x;
screen_coords[i].y = y;
}
if (! visible)
continue;
// draw scenery object
polygons = scenery->polygons;
for (i = 0; i < scenery->numPolygons; i++)
{
colour = (BYTE)*polygons++;
sides = *polygons++;
// store all polygon's points
for (j = 0; j < sides; j++)
{
offset = *polygons++;
points[j].x = screen_coords[offset].x;
points[j].y = screen_coords[offset].y;
}
// draw current polygon
SetTextureColour(SCR_BASE_COLOUR+colour);
if (sides >= 3)
DrawPolygon(points, sides);
}
}
}
/* ======================================================================================= */
/* Function: ClipLine */
/* */
/* Description: Clip line co-ordinates to screen boundaries */
/* Return FALSE if line is entirely off screen */
/* ======================================================================================= */
static long ClipLine( long *x1ptr,
long *y1ptr,
long *x2ptr,
long *y2ptr,
long screen_width,
long screen_height )
{
long on_screen = FALSE;
long x1 = *x1ptr, y1 = *y1ptr,
x2 = *x2ptr, y2 = *y2ptr;
long max_x = screen_width - 1;
long max_y = screen_height - 1;
// clip x1
if (x1 < 0)
{
// x1 is off left of screen
if (x2 < 0)
goto store_line; // entire line is off left of screen
else
{
// clip line to left edge, giving a new value for y1
y1 -= ((x1 * (y2-y1)) / (x2-x1));
x1 = 0;
}
}
else
if (x1 > max_x)
{
// x1 is off right of screen
if (x2 > max_x)
goto store_line; // entire line is off right of screen
else
{
// clip line to right edge, giving a new value for y1
y1 -= (((x1-max_x) * (y2-y1)) / (x2-x1));
x1 = max_x;
}
}
// clip y1
if (y1 < 0)
{
// y1 is off top of screen
if (y2 < 0)
goto store_line; // entire line is off top of screen
else
{
// clip line to top edge, giving a new value for x1
x1 -= ((y1 * (x2-x1)) / (y2-y1));
y1 = 0;
// check new x1 is on screen
if ((x1 < 0) || (x1 > max_x))
goto store_line;
}
}
else
if (y1 > max_y)
{
// y1 is off bottom of screen
if (y2 > max_y)
goto store_line; // entire line is off bottom of screen
else
{
// clip line to bottom edge, giving a new value for x1
x1 -= (((y1-max_y) * (x2-x1)) / (y2-y1));
y1 = max_y;
// check new x1 is on screen
if ((x1 < 0) || (x1 > max_x))
goto store_line;
}
}
// clip x2
if (x2 < 0)
{
// x2 is off left of screen
// clip line to left edge, giving a new value for y2
y2 -= ((x2 * (y1-y2)) / (x1-x2));
x2 = 0;
}
else
if (x2 > max_x)
{
// x2 is off right of screen