nanocoat/src/modelessStars.c

   1 /* -*- Mode: C; indent-tabs-mode: t; tab-width: 4 -*-
   2 // ---------------------------------------------------------------------------
   3 // SquirrelJME
   4 //     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
   5 // ---------------------------------------------------------------------------
   6 // SquirrelJME is under the Mozilla Public License Version 2.0.
   7 // See license.mkd for licensing and copyright information.
   8 // -------------------------------------------------------------------------*/
   9
  10 #include "sjme/modelessStars.h"
  11
  12 sjme_errorCode sjme_modelessStars(
  13         sjme_attrInOutNotNull sjme_modelessStarState* state,
  14         sjme_attrInNotNull uint32_t* buf,
  15         sjme_attrInPositiveNonZero sjme_jint width,
  16         sjme_attrInPositiveNonZero sjme_jint height,
  17         sjme_attrInPositiveNonZero sjme_jint pitch,
  18         sjme_attrInValue sjme_jint tick)
  19 {
  20         sjme_modelessStar* modelessStar;
  21         uint32_t* bufSlice;
  22         sjme_modelessStarColor colors[SJME_NUM_MODELESS_STAR_COLOR_IDS];
  23         sjme_modelessStarColor* startColor;
  24         sjme_modelessStarColor* endColor;
  25         sjme_modelessStarColor* atColor;
  26         sjme_modelessStarColor* sliceColor;
  27         sjme_jint h, y, x, next;
  28         sjme_juint rawHex;
  29
  30         /* Make sure input values are fine. */
  31         if (state == NULL || buf == NULL || width <= 0 || height <= 0 ||
  32                 pitch <= 0)
  33                 return SJME_ERROR_INVALID_ARGUMENT;
  34
  35         /* Easier pointers. */
  36         startColor = &colors[SJME_MODELESS_STAR_COLOR_ID_START];
  37         endColor = &colors[SJME_MODELESS_STAR_COLOR_ID_END];
  38         atColor = &colors[SJME_MODELESS_STAR_COLOR_ID_AT];
  39         sliceColor = &colors[SJME_MODELESS_STAR_COLOR_ID_SLICE];
  40
  41         /* Set base color information. */
  42         startColor->xrgb[0] = 0x00 << SJME_MODELESS_STAR_COLOR_SHIFT;
  43         startColor->xrgb[1] = 0x5B << SJME_MODELESS_STAR_COLOR_SHIFT;
  44         startColor->xrgb[2] = 0xCE << SJME_MODELESS_STAR_COLOR_SHIFT;
  45         startColor->xrgb[3] = 0xFA << SJME_MODELESS_STAR_COLOR_SHIFT;
  46         endColor->xrgb[0] = 0x00 << SJME_MODELESS_STAR_COLOR_SHIFT;
  47         endColor->xrgb[1] = 0xF5 << SJME_MODELESS_STAR_COLOR_SHIFT;
  48         endColor->xrgb[2] = 0xA9 << SJME_MODELESS_STAR_COLOR_SHIFT;
  49         endColor->xrgb[3] = 0xB8 << SJME_MODELESS_STAR_COLOR_SHIFT;
  50
  51         /* Set middle color. */
  52         for (x = 0; x < 4; x++)
  53         {
  54                 /* Set starting color. */
  55                 atColor->xrgb[x] =
  56                         startColor->xrgb[x];
  57
  58                 /* Set slice color. */
  59                 if (endColor->xrgb[x] != startColor->xrgb[x])
  60                         sliceColor->xrgb[x] = (endColor->xrgb[x] -
  61                                                                           startColor->xrgb[x]) / height;
  62                 else
  63                         sliceColor->xrgb[x] = 0;
  64         }
  65
  66         /* Draw in each color slice. */
  67         for (h = 0; h < height; h++)
  68         {
  69                 /* Determine where to draw in the slice. */
  70                 bufSlice = &buf[pitch * h];
  71
  72                 /* Determine the actual color hex. */
  73                 rawHex = 0;
  74                 for (x = 0; x < 4; x++)
  75                 {
  76                         rawHex <<= 8;
  77                         rawHex |= (atColor->xrgb[x] >>
  78                                 SJME_MODELESS_STAR_COLOR_SHIFT) & 0xFF;
  79                 }
  80
  81                 /* Just set it all to that color. */
  82                 for (x = 0; x < width; x++)
  83                         bufSlice[x] = rawHex;
  84
  85                 /* Shift color closer. */
  86                 for (x = 0; x < 4; x++)
  87                 {
  88                         /* If already at this color, do not go there. */
  89                         next = atColor->xrgb[x];
  90                         if (next == endColor->xrgb[x])
  91                                 continue;
  92
  93                         /* Determine next color. */
  94                         next += sliceColor->xrgb[x];
  95
  96                         /* Make sure color stays in bounds. */
  97                         if (next > 0xFF0000)
  98                                 next = 0xFF0000;
  99                         else if (next < 0x000000)
 100                                 next = 0x000000;
 101
 102                         /* Go to this color. */
 103                         atColor->xrgb[x] = next;
 104                 }
 105         }
 106
 107         /* Draw random star positions. */
 108         for (h = 0; h < SJME_MODELESS_STAR_COUNT; h++)
 109         {
 110                 /* Get this star. */
 111                 modelessStar = &state->modelessStars[h];
 112
 113                 /* Does this star need to be initialized? */
 114                 if (modelessStar->shining == SJME_JNI_FALSE)
 115                 {
 116                         /* Not creating stars yet, and is not shining. */
 117                         if (state->lockStarCreation > 0)
 118                         {
 119                                 /* Count down though... */
 120                                 state->lockStarCreation--;
 121
 122                                 continue;
 123                         }
 124
 125                         /* Star is shining now. */
 126                         modelessStar->shining = SJME_JNI_TRUE;
 127
 128                         /* Set random position on the screen. */
 129                         if (state->latchedFirstGo)
 130                                 modelessStar->x = width - 1;
 131                         else
 132                                 modelessStar->x = rand() % width;
 133                         modelessStar->y = rand() % height;
 134
 135                         /* Set a random speed for the star. */
 136                         modelessStar->speed = (rand() % 4) + 1;
 137
 138                         /* Do not initialize another star just yet. */
 139                         state->lockStarCreation = (tick % 25) + (rand() % 50);
 140                         state->lockStarCreationLast = state->lockStarCreation;
 141                 }
 142
 143                 /* Move star to the left. */
 144                 modelessStar->x -= modelessStar->speed;
 145
 146                 /* Did the star fall off the screen? */
 147                 if (modelessStar->x < 0)
 148                 {
 149                         modelessStar->shining = SJME_JNI_FALSE;
 150
 151                         /* Do not draw this star. */
 152                         continue;
 153                 }
 154
 155                 /* Draw star. */
 156                 x = modelessStar->x;
 157                 y = modelessStar->y;
 158                 buf[(pitch * y) + x] = 0x00FFFFFF;
 159
 160                 /* Do this step again to tick some more? */
 161                 if (!state->latchedFirstGo)
 162                 {
 163                         /* Reset counter. */
 164                         h = -1;
 165
 166                         /* No longer the first go. */
 167                         state->latchedFirstGo = SJME_JNI_TRUE;
 168                 }
 169         }
 170
 171         /* Handled successfully. */
 172         return SJME_JNI_TRUE;
 173 }