77 lines
3.3 KiB
C
77 lines
3.3 KiB
C
/* textures.c — 裸 RGBA 纹理绘制实现（M2）
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*
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* 数组字节序 R,G,B,A；framebuffer u32 = 0xAARRGGBB。
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* 双线性插值（像素中心对齐，8.8 定点）+ src-over alpha。
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*/
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#include "ascii_font.h" /* 顺序敏感：必须先于 textures.h（deshab_ui.h 需 g_ascii） */
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#include "textures.h"
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void tex_draw_scaled(du_context *ctx, const tex_u8 *rgba, int sw, int sh,
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int x, int y, int w, int h, int dim) {
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if (!ctx || !rgba || sw <= 0 || sh <= 0 || w <= 0 || h <= 0) return;
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if (dim < 0) dim = 0;
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if (dim > 256) dim = 256;
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int fw = (int)ctx->width, fh = (int)ctx->height;
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tex_u32 *fb = ctx->fb;
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tex_i64 pitch = (tex_i64)ctx->pitch / 4; /* u32 单位 */
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for (int dy = 0; dy < h; dy++) {
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int py = y + dy;
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if (py < 0 || py >= fh) continue;
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tex_i64 fy64 = ((tex_i64)dy * sh << 8) / h;
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int sy0 = (int)(fy64 >> 8);
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int fy = (int)(fy64 & 0xFF);
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int sy1 = (sy0 + 1 < sh) ? sy0 + 1 : sy0;
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if (sy0 >= sh) sy0 = sy1 = sh - 1;
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tex_u32 *dline = fb + (tex_i64)py * pitch;
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for (int dx = 0; dx < w; dx++) {
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int px = x + dx;
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if (px < 0 || px >= fw) continue;
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tex_i64 fx64 = ((tex_i64)dx * sw << 8) / w;
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int sx0 = (int)(fx64 >> 8);
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int fx = (int)(fx64 & 0xFF);
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int sx1 = (sx0 + 1 < sw) ? sx0 + 1 : sx0;
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if (sx0 >= sw) sx0 = sx1 = sw - 1;
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const tex_u8 *p00 = rgba + ((tex_i64)sy0 * sw + sx0) * 4;
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const tex_u8 *p10 = rgba + ((tex_i64)sy0 * sw + sx1) * 4;
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const tex_u8 *p01 = rgba + ((tex_i64)sy1 * sw + sx0) * 4;
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const tex_u8 *p11 = rgba + ((tex_i64)sy1 * sw + sx1) * 4;
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tex_u32 a, r, g, b;
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{
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tex_u32 rtop = ((tex_u32)p00[0] * (256 - fx) + (tex_u32)p10[0] * fx) >> 8;
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tex_u32 rbot = ((tex_u32)p01[0] * (256 - fx) + (tex_u32)p11[0] * fx) >> 8;
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tex_u32 gtop = ((tex_u32)p00[1] * (256 - fx) + (tex_u32)p10[1] * fx) >> 8;
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tex_u32 gbot = ((tex_u32)p01[1] * (256 - fx) + (tex_u32)p11[1] * fx) >> 8;
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tex_u32 btop = ((tex_u32)p00[2] * (256 - fx) + (tex_u32)p10[2] * fx) >> 8;
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tex_u32 bbot = ((tex_u32)p01[2] * (256 - fx) + (tex_u32)p11[2] * fx) >> 8;
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tex_u32 atop = ((tex_u32)p00[3] * (256 - fx) + (tex_u32)p10[3] * fx) >> 8;
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tex_u32 abot = ((tex_u32)p01[3] * (256 - fx) + (tex_u32)p11[3] * fx) >> 8;
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r = (rtop * (256 - fy) + rbot * fy) >> 8;
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g = (gtop * (256 - fy) + gbot * fy) >> 8;
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b = (btop * (256 - fy) + bbot * fy) >> 8;
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a = (atop * (256 - fy) + abot * fy) >> 8;
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}
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if (a == 0) continue;
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/* 亮度衰减（boot 背景） */
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r = r * dim >> 8; g = g * dim >> 8; b = b * dim >> 8;
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tex_u32 dst = dline[px];
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if (a >= 255) {
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dline[px] = 0xFF000000u | (r << 16) | (g << 8) | b;
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} else {
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tex_u32 dr = (dst >> 16) & 0xFF, dg = (dst >> 8) & 0xFF, db = dst & 0xFF;
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tex_u32 na = 255 - a;
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dline[px] = 0xFF000000u |
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(((r * a + dr * na) >> 8) << 16) |
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(((g * a + dg * na) >> 8) << 8) |
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((b * a + db * na) >> 8);
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}
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}
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}
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}
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