Added playerLives variable that is updated when the ball is reset, and used SDL_Image to load bitmaps of heart icons and function to visually represent the lives

SDL Surface to GL Texture code in loadTextures function used from http://www.sdltutorials.com/sdl-tip-sdl-surface-to-opengl-texture

breakout/breakout.c

@@ -2,8 +2,11 @@
 #include <Windows.h>
 #include <SDL.h>
 #include <SDL_ttf.h>
+#include <SDL_image.h>
 #else
 #include <SDL2/SDL.h>
+#include <SDL2/SDL_ttf.h>
+#include <SDL2/SDL_image.h>
 #endif
 #include <GL/gl.h>
 #include <GL/glu.h>
@@ -65,16 +68,20 @@ double heronsFormula(coord a, coord b, coord c) {
   double s = (A + B + C) / 2;
   return sqrt(s*(s - A)*(s - B)*(s - C));
 }
+
+int loadTextures(GLuint *texture, const char *imageLoc);
+
 char vertexWithinQuad(coord point, coord *quad);
 
 void updatePaddle(Uint32 tickrate, paddle *thePaddle, char moveX, int winWidth, int winHeight);
-void updateBall(Uint32 tickrate, ball *theBall, paddle *thePaddle, int winWidth, int winHeight, brick *bricks, int brickCount);
+void updateBall(Uint32 tickrate, ball *theBall, paddle *thePaddle, int winWidth, int winHeight, brick *bricks, int brickCount, int *playerLives);
 void updateScore(int *playerScore, brick *bricks, int brickCount);
 
+void drawHearts(GLuint heartFullTex, GLuint heartEmptyTex, int playerLives, int winWidth, int winHeight);
 void drawPaddle(paddle *thePaddle, int winWidth, int winHeight, colour *c);
 void drawBall(ball *theBall, colour *c);
-void drawBg(int winWidth, int winHeight, colour *c1, colour *c2);
 void drawBricks(brick *bricks, int brickCount, int winWidth, int winHeight, colour *colours);
+void drawBg(int winWidth, int winHeight, colour *c1, colour *c2);
 
 void initialiseBricks(brick *bricks, int *brickCount);
 
@@ -88,6 +95,7 @@ int main(void) {
    *  3: Error creating context
    *  4: SDL_TTF init fail
    *  5: Error loading font(s)
+   *  6: Error loading image asset(s)
    *
    */
   
@@ -162,6 +170,8 @@ int main(void) {
   glShadeModel(GL_SMOOTH); // GL_FLAT for flat shading instead
   glEnable(GL_DEPTH_TEST); // Enables depth comparisons
   glEnable(GL_TEXTURE_2D); // Enables use of textures
+  glAlphaFunc(GL_GREATER, 0);
+  glEnable(GL_ALPHA_TEST);
 
   glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
 
@@ -220,6 +230,8 @@ int main(void) {
 
   int playerScore = 0;
 
+  int playerLives = 3;
+
   /*
    * ----------------
    *  Font stuff
@@ -238,6 +250,19 @@ int main(void) {
     .b = 255
   };
 
+  /*
+   * --------------------------------
+   *  Loading required textures
+   * --------------------------------
+   */
+
+  GLuint heartFullTex; 
+  GLuint heartEmptyTex;
+  if (
+    loadTextures(&heartEmptyTex, "assets/heartUsed.png") ||
+    loadTextures(&heartFullTex, "assets/heartFull.png")  > 1) {
+    return 6;
+  }
   /*
    * ----------------
    *  Let's go!
@@ -303,8 +328,11 @@ int main(void) {
     */
 
     updatePaddle(tickrate, &thePaddle, moveX, winWidth, winHeight);
-    updateBall(tickrate, &theBall, &thePaddle, winWidth, winHeight, &bricks, brickCount);
+    updateBall(tickrate, &theBall, &thePaddle, winWidth, winHeight, &bricks, brickCount, &playerLives);
     updateScore(&playerScore, &bricks, brickCount);
+    if (playerLives < 1) {
+      go = 0;
+    }
 
     if (step % (subSteps+1) == 0) {
       //step = 0;
@@ -316,7 +344,7 @@ int main(void) {
 
       SDL_GL_MakeCurrent(window1, context1);
 
-      sprintf(windowTitle, "Breakout: Score %d", playerScore);
+      sprintf(windowTitle, "Breakout: Score (%d), lives remaining (%d)", playerScore, playerLives);
       SDL_SetWindowTitle(window1, windowTitle);
 
       glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
@@ -335,6 +363,7 @@ int main(void) {
       bgcol1.b = 0.6078; /*155*/ bgcol2.b = 0.4431; /*113*/
       bgcol1.a = 1.0000; /*255*/ bgcol2.a = 1.0000; /*255*/
 
+      drawHearts(heartFullTex, heartEmptyTex, playerLives, winWidth, winHeight);
       drawPaddle(&thePaddle, winWidth, winHeight, &paddleCol);
       drawBall(&theBall, &paddleCol);
       drawBricks(&bricks, brickCount, winWidth, winHeight, &brickColours);
@@ -365,6 +394,37 @@ int main(void) {
   return 0;
 }
 
+int loadTextures(GLuint *texture, const char *imageLoc) {
+  char errorMsg[512];
+  sprintf(errorMsg, "[FAILED] Opening %s", imageLoc);
+  SDL_Surface *surface = IMG_Load(imageLoc);
+  if (surface == NULL) {
+    fprintf(stderr, errorMsg);
+    return 1;
+  }
+  *texture = 0;
+
+  // Start of code from SDLTutorials.com
+
+  int Mode = GL_RGB;
+
+  glGenTextures(1, texture);
+  glBindTexture(GL_TEXTURE_2D, *texture);
+
+  if (surface->format->BytesPerPixel == 4) {
+    Mode = GL_RGBA;
+  }
+  glTexImage2D(GL_TEXTURE_2D, 0, Mode, surface->w, surface->h, 0, Mode, GL_UNSIGNED_BYTE, surface->pixels);
+
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+  // End of code from SDLTutorials.com
+  // Tim Jones (2011) SDL Surface to OpenGL Texture, Available at: http://www.sdltutorials.com/sdl-tip-sdl-surface-to-opengl-texture (Accessed: 10/01/2018)
+
+  return 0;
+}
+
 char vertexWithinQuad(coord point, coord *quad) {
   double quadArea = heronsFormula(quad[0], quad[1], quad[2]) + heronsFormula(quad[1], quad[2], quad[3]);
   double testArea = 0;
@@ -385,7 +445,7 @@ void updatePaddle(Uint32 tickrate, paddle *thePaddle, char moveX, int winWidth,
   if (thePaddle->x > winWidth-(thePaddle->width/2)) thePaddle->x = winWidth-(thePaddle->width/2);
 }
 
-void updateBall(Uint32 tickrate, ball *theBall, paddle *thePaddle, int winWidth, int winHeight, brick *bricks, int brickCount) {
+void updateBall(Uint32 tickrate, ball *theBall, paddle *thePaddle, int winWidth, int winHeight, brick *bricks, int brickCount, int *playerLives) {
   double ballNX = theBall->x + theBall->vX * 0.1 * tickrate; // Calculates the position of the ball's centre on the next step
   double ballNY = theBall->y + theBall->vY * 0.1 * tickrate;
 
@@ -482,6 +542,7 @@ void updateBall(Uint32 tickrate, ball *theBall, paddle *thePaddle, int winWidth,
     theBall->y = 0;
     theBall->vX = theBall->initVX;
     theBall->vY = theBall->initVY;
+    *playerLives -= 1;
   }
 
   // Update the ball's position
@@ -512,6 +573,34 @@ void updateScore(int *playerScore, brick *bricks, int brickCount) {
   }
 }
 
+void drawHearts(GLuint heartFullTex, GLuint heartEmptyTex, int playerLives, int winWidth, int winHeight) {
+  coord locations[3] = { {.x = -19, .y = -32}, { .x = 0, .y = -32 }, { .x = 19, .y = -32 } };
+
+  for (int i = 0; i < 3; i++) {
+    if (i > playerLives-1) {
+      glBindTexture(GL_TEXTURE_2D, heartEmptyTex);
+    } else {
+      glBindTexture(GL_TEXTURE_2D, heartFullTex);
+    }
+    GLint matrixmode = 0;
+    glGetIntegerv(GL_MATRIX_MODE, &matrixmode);
+    glPushMatrix();
+    glTranslated(0.0, (winHeight/2), 0.0);
+
+    glBegin(GL_QUADS);
+      glTexCoord2f(0, 0); glVertex3d(0.0+locations[i].x, 0.0+locations[i].y, 0.0);
+      glTexCoord2f(0, 1); glVertex3d(0.0+locations[i].x, -15.0 + locations[i].y, 0.0);
+      glTexCoord2f(1, 1); glVertex3d(15.0+locations[i].x, -15.0 + locations[i].y, 0.0);
+      glTexCoord2f(1, 0); glVertex3d(15.0+locations[i].x, 0.0 + locations[i].y, 0.0);
+    glEnd();
+
+    glPopMatrix();
+    glMatrixMode(matrixmode);
+  }
+
+  glBindTexture(GL_TEXTURE_2D, 0);
+}
+
 void drawBg(int winWidth, int winHeight, colour *c1, colour *c2) {
   GLint matrixmode = 0;
   glGetIntegerv(GL_MATRIX_MODE, &matrixmode);