[Add] Animated nebulae ftw!!!

src/nebulae.c

@@ -7,8 +7,11 @@
 #include "log.h"
 #include "opengl.h"
 #include "lfile.h"
+#include "rng.h"
 #include "perlin.h"
 
+#define NEBU_DT_MAX           1.
+
 #define NEBULAE_Z             16  /* Z plane. */
 #define NEBULAE_PATH          "gen/nebu_%02d.png"
 
@@ -18,6 +21,10 @@ static int nebu_w = 0;
 static int nebu_h = 0;
 static int nebu_pw, nebu_ph;
 
+/* Information on rendering. */
+static int cur_nebu[2] = { 0, 1 };
+static unsigned int last_render = 0;
+
 static int nebu_checkCompat(const char* file);
 static void saveNebulae(float* map, const uint32_t w, const uint32_t h,
     const char* file);
@@ -60,6 +67,7 @@ void nebu_init(void) {
       WARN("Nebulae raw size doesn't match expected! (%dx%d instead of %dx%d)",
           nebu_sur->w, nebu_sur->h, nebu_pw, nebu_ph);
 
+    /* Prepare to load into OpenGL. */
     nebu_sur = gl_prepareSurface(nebu_sur);
     if((nebu_sur->w != nebu_pw) || (nebu_sur->h != nebu_ph))
       WARN("Nebulae size doesn't match expected! (%dx%d instead of %dx%d)",
@@ -70,6 +78,7 @@ void nebu_init(void) {
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     
+    /* Store into opengl saving only alpha channel in video memory. */
     SDL_LockSurface(nebu_sur);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, nebu_sur->w, nebu_sur->h,
         0, GL_RGBA, GL_UNSIGNED_BYTE, nebu_sur->pixels);
@@ -89,40 +98,94 @@ void nebu_exit(void) {
 
 /* Render the nebulae. */
 void nebu_render(void) {
-  int n;
-  double x, y, w, h, tx, ty, tw, th;
+  unsigned int t;
+  double dt;
+  double tw, th;
+  GLfloat col[4];
+  int tmp;
 
-  n = 0;
+  /* Calculate frame to draw. */
+  t = SDL_GetTicks();
+  dt = (t - last_render) / 1000.;
+  if(dt > NEBU_DT_MAX) { /* Time to change. */
+    tmp = cur_nebu[0];
+    cur_nebu[0] += cur_nebu[0] - cur_nebu[1];
+    cur_nebu[1] = tmp;
+    if(cur_nebu[0]+1 > NEBULAE_Z)
+      cur_nebu[0] = NEBULAE_Z - 2;
+    else if(cur_nebu[0] < 0)
+      cur_nebu[0] = 1;
 
-  x = -SCREEN_W/2.;
-  y = -SCREEN_H/2.;
+    last_render = t;
+    dt = 0.;
+  }
 
-  w = SCREEN_W;
-  h = SCREEN_H;
-
-  tx = 0.;
-  ty = 0.;
+  col[0] = cPurple.r;
+  col[1] = cPurple.g;
+  col[2] = cPurple.b;
+  col[3] = dt / NEBU_DT_MAX;
 
   tw = (double)nebu_w / (double)nebu_pw;
   th = (double)nebu_h / (double)nebu_ph;
 
+  /* Set up the targets. */
+  /* Texture 0. */
+  glActiveTexture(GL_TEXTURE0);
   glEnable(GL_TEXTURE_2D);
-  /*glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);*/
-  glBindTexture(GL_TEXTURE_2D, nebu_textures[n]);
-  COLOUR(cPurple);
+  glBindTexture(GL_TEXTURE_2D, nebu_textures[cur_nebu[0]]);
+
+  /* Texture 1. */
+  glActiveTexture(GL_TEXTURE1);
+  glEnable(GL_TEXTURE_2D);
+  glBindTexture(GL_TEXTURE_2D, nebu_textures[cur_nebu[1]]);
+
+  /* Prepare it. */
+  glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
+  glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_INTERPOLATE);
+  glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_INTERPOLATE);
+  /* Colour. */
+  glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, col);
+
+  /* Arguments. */
+  glTexEnvf(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_CONSTANT);
+  glTexEnvf(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_TEXTURE1);
+  glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
+  glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
+  /* Arg 1. */
+  glTexEnvf(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_CONSTANT);
+  glTexEnvf(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_PREVIOUS);
+  glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
+  glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_ALPHA, GL_SRC_ALPHA);
+  /* Arg 2. */
+  glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_RGB, GL_CONSTANT);
+  glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_ALPHA, GL_CONSTANT);
+  glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_SRC_ALPHA);
+  glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_SRC_ALPHA);
+
+  /* Now render. */
   glBegin(GL_QUADS);
-    glTexCoord2d(tx, ty);
-    glVertex2d(x, y);
+    glMultiTexCoord2d(GL_TEXTURE0, 0., 0.);
+    glMultiTexCoord2d(GL_TEXTURE1, 0., 0.);
+    glVertex2d(-SCREEN_W/2., -SCREEN_H/2.);
 
-    glTexCoord2d(tx+tw, ty);
-    glVertex2d(x+w, y);
-
-    glTexCoord2d(tx+tw, ty+th);
-    glVertex2d(x+w, y+h);
-
-    glTexCoord2d(tx, ty+th);
-    glVertex2d(x, y+h);
+    glMultiTexCoord2d(GL_TEXTURE0, tw, 0.);
+    glMultiTexCoord2d(GL_TEXTURE1, tw, 0.);
+    glVertex2d(SCREEN_W/2., -SCREEN_H/2.);
+    
+    glMultiTexCoord2d(GL_TEXTURE0, tw, th);
+    glMultiTexCoord2d(GL_TEXTURE1, tw, th);
+    glVertex2d(SCREEN_W/2., SCREEN_H/2.);
+  
+    glMultiTexCoord2d(GL_TEXTURE0, 0., th);
+    glMultiTexCoord2d(GL_TEXTURE1, 0., th);
+    glVertex2d(-SCREEN_W/2., SCREEN_H/2.);
   glEnd();
+
+  /* Clean up. */
+  glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
+  glDisable(GL_TEXTURE_2D);
+  glActiveTexture(GL_TEXTURE0);
+  glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
   glDisable(GL_TEXTURE_2D);
 
   /* Did anything fail? */

src/perlin.c

@@ -183,7 +183,7 @@ float* noise_genNebulaeMap(const int w, const int h, const int n, float rug) {
   lacunarity = NOISE_DEFAULT_LACUNARITY;
   zoom = rug * ((float)h/768.)*((float)w/1024.);
 
-  /* Create noiuse and data. */
+  /* Create noise and data. */
   noise = noise_new(hurst, lacunarity);
 
   nebulae = malloc(sizeof(float)*w*h*n);