commit stuff

game.c

@@ -1,4 +1,6 @@
 #include <stdio.h>
+#include <math.h>
+#include <conio.h>
 
 #include "vga.h"
 #include "keyboard.h"
@@ -10,7 +12,7 @@ struct BMPImage spritesheetImage;
 struct VGAColor vgaColors[256];
 
 struct SpriteRender arenaWallTop, arenaWallSide, arenaFloor;
-struct SpriteRender rabbit;
+struct SpriteRender rabbit, mouse;
 
 void setupWallSprites() {
   buildSpriteFromSpritesheet(
@@ -38,6 +40,18 @@ void setupRabbitSprites() {
     &rabbit,
     0, 20, 16, 16
   );
+
+  rabbit.offsetX = 8;
+  rabbit.offsetY = 15;
+
+  buildSpriteFromSpritesheet(
+    &spritesheetImage,
+    &mouse,
+    16, 20, 8, 8
+  );
+
+  mouse.offsetX = 4;
+  mouse.offsetY = 4;
 }
 
 char arenaLayout[10][10] = {
@@ -99,10 +113,25 @@ int rabbitLimits[2][2] = {
 
 signed char rabbitVelocity[2] = { 0, 0 };
 
-void renderRabbit() {
+struct SpriteBounds bounds;
+struct MouseStatus mouseStatus;
+char mousePosition[2] = { 0, 0 };
+
+void setupRabbitDrawing() {
   rabbit.x = rabbitPosition[0];
   rabbit.y = rabbitPosition[1];
+}
 
+void setupMouseDrawing() {
+  mouse.x = mousePosition[0];
+  mouse.y = mousePosition[1];
+}
+
+void renderMouse() {
+  drawSprite(&mouse);
+}
+
+void renderRabbit() {
   drawSprite(&rabbit);
 }
 
@@ -155,34 +184,75 @@ void handleRabbitMovement() {
   }
 }
 
-void drawOnlyRabbitArena() {
-  int rabbitLeftTileX, rabbitRightTileX,
-      rabbitTopTileY, rabbitBottomTileY;
+void drawOnlyArena() {
+  int leftTileX, rightTileX,
+      topTileY, bottomTileY;
 
-  rabbitLeftTileX = rabbitPosition[0] / 20;
-  rabbitRightTileX = (rabbitPosition[0] + 16) / 20;
-  rabbitTopTileY = rabbitPosition[1] / 20;
-  rabbitBottomTileY = (rabbitPosition[1] + 16) / 20;
+  leftTileX = bounds.left / 20;
+  rightTileX = bounds.right / 20;
+  topTileY = bounds.top / 20;
+  bottomTileY = bounds.bottom / 20;
 
-  renderArenaTile(rabbitLeftTileX, rabbitTopTileY);
-  if (rabbitLeftTileX != rabbitRightTileX) {
-    renderArenaTile(rabbitRightTileX, rabbitTopTileY);
-    if (rabbitTopTileY != rabbitBottomTileY) {
-      renderArenaTile(rabbitRightTileX, rabbitBottomTileY);
+  renderArenaTile(leftTileX, topTileY);
+  if (leftTileX != rightTileX) {
+    renderArenaTile(rightTileX, topTileY);
+    if (topTileY != bottomTileY) {
+      renderArenaTile(rightTileX, bottomTileY);
     }
   }
-  if (rabbitTopTileY != rabbitBottomTileY) {
-    renderArenaTile(rabbitLeftTileX, rabbitBottomTileY);
+  if (topTileY != bottomTileY) {
+    renderArenaTile(leftTileX, bottomTileY);
   }
 }
 
+void drawOnlyMouseArena() {
+  getSpriteBounds(&mouse, &bounds);
+
+  drawOnlyArena();
+}
+
+void drawOnlyRabbitArena() {
+  getSpriteBounds(&rabbit, &bounds);
+
+  drawOnlyArena();
+}
+
+#define RAD2DEG (180/3.14159)
+#define DEG2RAD (3.14159/180)
+#define MOUSE_DISTANCE (32)
+
+void calculateMouseAngle() {
+  float distanceX, distanceY;
+  float angle;
+
+  char buffer[20];
+
+  distanceX = mouseStatus.xPosition - rabbitPosition[0];
+  distanceY = mouseStatus.yPosition - rabbitPosition[1];
+
+  angle = atan2(distanceY, distanceX) * 180 / 3.14159;
+
+  sprintf(buffer, "%f", angle);
+  writeString(buffer, 0, 2);
+
+  sprintf(buffer, "%f", distanceX);
+  writeString(buffer, 0, 3);
+
+  sprintf(buffer, "%d", mouseStatus.xPosition);
+  writeString(buffer, 0, 4);
+
+  distanceX = cos(angle * DEG2RAD) * MOUSE_DISTANCE;
+  distanceY = sin(angle * DEG2RAD) * MOUSE_DISTANCE;
+
+  mousePosition[0] = rabbitPosition[0] + distanceX;
+  mousePosition[1] = rabbitPosition[1] + distanceY;
+}
+
 int main(void) {
   FILE *fh;
   int keepRunning = 1;
-  struct MouseStatus mouseStatus;
 
   installKeyboardHandler();
-  activateMouse(&mouseStatus);
   initializeDrawBuffer();
 
   fh = fopen("sprtsht.bmp", "rb");
@@ -198,18 +268,26 @@ int main(void) {
   bmp256ColorPaletteToVGAColorPalette(&spritesheetImage, vgaColors);
   setVGAColors(vgaColors, 256);
 
+  activateMouse(&mouseStatus);
+
   buildArena();
 
   while (keepRunning) {
     readMouse(&mouseStatus);
     populateKeyboardKeydownState();
     handleRabbitMovement();
+    calculateMouseAngle();
 
     waitStartVbl();
 
+    setupRabbitDrawing();
+    setupMouseDrawing();
     drawOnlyRabbitArena();
+    drawOnlyMouseArena();
     renderRabbit();
+    renderMouse();
     copyDrawBufferToDisplay();
+    calculateMouseAngle();
 
     waitEndVbl();
 

mouse_io.c

@@ -6,6 +6,9 @@
 
 struct MouseStatus *_status;
 
+/**
+ * Ensure this is called after setting the desired video mode.
+ */
 int activateMouse(struct MouseStatus *status) {
   union REGS regs;
   int mouseActivated;

pc_stuff.c

@@ -21,3 +21,32 @@ void waitStartVbl() {
 void waitEndVbl() {
     while (!(inp(INPUT_STATUS) & VBLANK));
 }
+
+#define FAILSAFE (80)
+
+void writeString(char *buffer, int x, int y) {
+  union REGS regs;
+
+  int i, currentX = x;
+  char c;
+
+  for (i = 0; i < FAILSAFE; ++i) {
+    c = buffer[i];
+    if (c == 0) break;
+
+    regs.h.ah = 0x02;
+    regs.h.bh = 0x00;
+    regs.h.dh = y;
+    regs.h.dl = currentX;
+    int386(BIOS_VIDEO_INTERRUPT, &regs, &regs);
+
+    regs.h.ah = 0x09;
+    regs.h.al = c;
+    regs.h.bh = 0x00;
+    regs.h.bl = 1;
+    regs.w.cx = 1;
+    int386(BIOS_VIDEO_INTERRUPT, &regs, &regs);
+
+    currentX++;
+  }
+}

pc_stuff.h

@@ -23,3 +23,4 @@ extern byte *VGA;
 void setVideoMode(byte);
 void waitStartVbl();
 void waitEndVbl();
+void writeString(char *, int x, int y);

setup.sh

@@ -1,3 +1,4 @@
 export WATCOM=~/Applications/open-watcom-v2/rel
 export INCLUDE=$WATCOM/h
+export LIB=$WATCOM/lib286/dos:$WATCOM/lib286
 export PATH=$WATCOM/binl64:$WATCOM/binl:$PATH

vga.c

@@ -55,7 +55,13 @@ void drawSprite(struct SpriteRender* sprite) {
   byte pixel;
 
   byte* spriteData = sprite->data;
-  byte* drawBufferPos = drawBuffer + sprite->x + (sprite->y * VGA_DISPLAY_WIDTH);
+  byte* drawBufferPos =
+    drawBuffer +
+    sprite->x -
+    sprite->offsetX +
+    (
+      (sprite->y - sprite->offsetY) * VGA_DISPLAY_WIDTH
+    );
 
   for (y = 0; y < sprite->height; ++y) {
     for (x = 0; x < sprite->width; ++x) {
@@ -72,6 +78,14 @@ void drawSprite(struct SpriteRender* sprite) {
   }
 }
 
+void getSpriteBounds(struct SpriteRender *sprite, struct SpriteBounds *bounds) {
+  bounds->top = sprite->y - sprite->offsetY;
+  bounds->bottom = bounds->top + sprite->height;
+
+  bounds->left = sprite->x - sprite->offsetX;
+  bounds->right = bounds->left + sprite->width;
+}
+
 void setVGAColors(struct VGAColor colors[], int totalColors) {
   int i;
 

vga.h

@@ -23,10 +23,21 @@ struct SpriteRender {
   unsigned int height;
   int transparentColor;
   unsigned int modulo;
+
+  int offsetX;
+  int offsetY;
+};
+
+struct SpriteBounds {
+  int top;
+  int right;
+  int bottom;
+  int left;
 };
 
 void drawSprite(struct SpriteRender *sprite);
 void buildSpriteFromSpritesheet(struct BMPImage*, struct SpriteRender*, int, int, int, int);
+void getSpriteBounds(struct SpriteRender *sprite, struct SpriteBounds *bounds);
 
 byte *initializeDrawBuffer();
 byte *getDrawBuffer();