85 lines
2.7 KiB
C
85 lines
2.7 KiB
C
#include "affine_background.h"
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#include "affine_background_gfx.h"
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#include "graphic_utils.h"
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BG_AFFINE bgaff_arr[SCREEN_HEIGHT + 1];
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static uint timer = 0;
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#define ANIMATION_SPEED_DIVISOR 16
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void affine_background_init()
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{
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memcpy32_tile8_with_palette_offset((u32*)&tile8_mem[AFFINE_BG_CBB], (const u32*)affine_background_gfxTiles, affine_background_gfxTilesLen/4, AFFINE_BG_PB);
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GRIT_CPY(&se_mem[AFFINE_BG_SBB], affine_background_gfxMap);
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affine_background_load_palette(affine_background_gfxPal);
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REG_BG_AFFINE[AFFINE_BG_IDX] = bg_aff_default;
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}
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// Pre-computes the affine matrices values for each scanline
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// and stores in bgaff_arr.
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// This is to be done in VBLANK so the HBLANK code
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// can just fetch the values quickly.
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IWRAM_CODE void affine_background_prep_bgaff_arr()
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{
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for (u16 vcount = 0; vcount < SCREEN_HEIGHT; vcount++)
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{
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AFF_SRC_EX asx = {32<<8, 64<<8, 120, 80, 0x0100, 0x0100, 0};
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const s32 timer_s32 = timer << 8;
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const s32 vcount_s32 = vcount << 8;
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const s16 vcount_s16 = vcount;
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const s32 vcount_sine = lu_sin(vcount_s32 + timer_s32 / ANIMATION_SPEED_DIVISOR); // dividing the timer by 16 to make the animation slower
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asx.scr_x = (SCREEN_WIDTH / 2); // 128 on x and y is an offset used to center the rotation
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asx.scr_y = vcount_s16 - (SCREEN_HEIGHT / 2); // scr_y must equal vcount otherwise the background will have no vertical difference
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asx.tex_x = vcount_sine;
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asx.tex_y = vcount_sine / 64;
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asx.sx = vcount_sine / 32;
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asx.sy = vcount_sine / 16;
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asx.alpha = vcount_sine + (timer_s32 / ANIMATION_SPEED_DIVISOR);
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bg_rotscale_ex(&bgaff_arr[vcount], &asx);
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}
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/* HBLANK occurs after the scanline so REG_VCOUNT represents the
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* the scanline that just passed, so when it's SCREEN_HEIGHT we will
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* actually be updating the first line
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*/
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bgaff_arr[SCREEN_HEIGHT] = bgaff_arr[0];
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}
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IWRAM_CODE void affine_background_hblank()
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{
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vu16 vcount = REG_VCOUNT;
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if ((vcount >= SCREEN_HEIGHT)) // Exit the function if the scanline is outside the screen
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{
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return;
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}
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// See comment in affine_background_prep_bgaff_arr()
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REG_BG_AFFINE[AFFINE_BG_IDX] = bgaff_arr[vcount + 1];
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}
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void affine_background_update()
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{
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affine_background_prep_bgaff_arr();
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timer++;
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}
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void affine_background_set_color(COLOR color)
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{
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memcpy16(&pal_bg_mem[AFFINE_BG_PB], affine_background_gfxPal, AFFINE_BG_PAL_LEN);
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for (int i = 0; i < AFFINE_BG_PAL_LEN; i++)
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{
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clr_rgbscale(&pal_bg_mem[AFFINE_BG_PB] + i, &pal_bg_mem[AFFINE_BG_PB] + i, 1, color);
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}
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}
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void affine_background_load_palette(const u16 *src)
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{
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memcpy16(&pal_bg_mem[AFFINE_BG_PB], src, AFFINE_BG_PAL_LEN);
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} |