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8bitworkshop/presets/verilog/racing_game.v

151 lines
4.1 KiB
Verilog

`include "hvsync_generator.v"
`include "sprite_bitmap.v"
`include "sprite_renderer.v"
/*
A simple racing game with two sprites and a scrolling playfield.
This version does not use a CPU; all logic is straight Verilog.
*/
module racing_game_top(clk, hsync, vsync, rgb, hpaddle, vpaddle);
input clk;
input hpaddle, vpaddle;
output hsync, vsync;
output [2:0] rgb;
wire display_on;
wire [8:0] hpos;
wire [8:0] vpos;
// player car position (set at VSYNC)
reg [7:0] player_x;
reg [7:0] player_y;
// paddle position (set continuously during frame)
reg [7:0] paddle_x;
reg [7:0] paddle_y;
// enemy car position
reg [7:0] enemy_x = 128;
reg [7:0] enemy_y = 128;
// enemy car direction, 1=right, 0=left
reg enemy_dir = 0;
reg [15:0] track_pos = 0; // player position along track (16 bits)
reg [7:0] speed = 31; // player velocity along track (8 bits)
// video sync generator
hvsync_generator hvsync_gen(
.clk(clk),
.reset(0),
.hsync(hsync),
.vsync(vsync),
.display_on(display_on),
.hpos(hpos),
.vpos(vpos)
);
// set paddle registers
always @(posedge hsync)
begin
if (!hpaddle) paddle_x <= vpos[7:0];
if (!vpaddle) paddle_y <= vpos[7:0];
end
// select player or enemy access to ROM
wire player_load = (hpos >= 256) && (hpos < 260);
wire enemy_load = (hpos >= 260);
// wire up car sprite ROM
// multiplex between player and enemy ROM address
wire [3:0] player_sprite_yofs;
wire [3:0] enemy_sprite_yofs;
wire [3:0] car_sprite_yofs = player_load ? player_sprite_yofs : enemy_sprite_yofs;
wire [7:0] car_sprite_bits;
car_bitmap car(
.yofs(car_sprite_yofs),
.bits(car_sprite_bits));
// signals for player sprite generator
wire player_vstart = {1'b0,player_y} == vpos;
wire player_hstart = {1'b0,player_x} == hpos;
wire player_gfx;
wire player_is_drawing;
// signals for enemy sprite generator
wire enemy_vstart = {1'b0,enemy_y} == vpos;
wire enemy_hstart = {1'b0,enemy_x} == hpos;
wire enemy_gfx;
wire enemy_is_drawing;
// player sprite generator
sprite_renderer player_renderer(
.clk(clk),
.vstart(player_vstart),
.load(player_load),
.hstart(player_hstart),
.rom_addr(player_sprite_yofs),
.rom_bits(car_sprite_bits),
.gfx(player_gfx),
.in_progress(player_is_drawing));
// enemy sprite generator
sprite_renderer enemy_renderer(
.clk(clk),
.vstart(enemy_vstart),
.load(enemy_load),
.hstart(enemy_hstart),
.rom_addr(enemy_sprite_yofs),
.rom_bits(car_sprite_bits),
.gfx(enemy_gfx),
.in_progress(enemy_is_drawing));
// signals for enemy bouncing off left/right borders
wire enemy_hit_left = (enemy_x == 64);
wire enemy_hit_right = (enemy_x == 192);
wire enemy_hit_edge = enemy_hit_left || enemy_hit_right;
// update player, enemy, track counters
// runs once per frame
always @(posedge vsync)
begin
player_x <= paddle_x;
player_y <= 180;
track_pos <= track_pos + {11'b0,speed[7:4]};
enemy_y <= enemy_y + {3'b0, speed[7:4]};
if (enemy_hit_edge)
enemy_dir <= !enemy_dir;
if (enemy_dir ^ enemy_hit_edge)
enemy_x <= enemy_x + 1;
else
enemy_x <= enemy_x - 1;
// collision check?
if (frame_collision)
speed <= 16;
else if (speed < ~paddle_y)
speed <= speed + 1;
else
speed <= speed - 1;
end
// set to 1 when player collides with enemy or track
reg frame_collision;
always @(posedge clk)
if (player_gfx && (enemy_gfx || track_gfx))
frame_collision <= 1;
else if (vsync)
frame_collision <= 0;
// track graphics signals
wire track_offside = (hpos[7:5]==0) || (hpos[7:5]==7);
wire track_shoulder = (hpos[7:3]==3) || (hpos[7:3]==28);
wire track_gfx = (vpos[5:1]!=track_pos[5:1]) && track_offside;
// combine signals for RGB output
wire r = display_on && (player_gfx || enemy_gfx || track_shoulder);
wire g = display_on && (player_gfx || track_gfx);
wire b = display_on && (enemy_gfx || track_shoulder);
assign rgb = {b,g,r};
endmodule