wip sw renderer...bsp is borked, also lots of other things

src/gfx/pxl8_lightmap.c

@@ -0,0 +1,113 @@
+#include "pxl8_lightmap.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+pxl8_lightmap* pxl8_lightmap_create(u32 width, u32 height, u32 scale) {
+    pxl8_lightmap* lm = calloc(1, sizeof(pxl8_lightmap));
+    if (!lm) return NULL;
+
+    lm->width = width;
+    lm->height = height;
+    lm->scale = scale;
+    lm->data = calloc(width * height * 3, sizeof(u8));
+    if (!lm->data) {
+        free(lm);
+        return NULL;
+    }
+
+    pxl8_lightmap_clear(lm, PXL8_LIGHTMAP_NEUTRAL, PXL8_LIGHTMAP_NEUTRAL, PXL8_LIGHTMAP_NEUTRAL);
+    return lm;
+}
+
+void pxl8_lightmap_destroy(pxl8_lightmap* lm) {
+    if (!lm) return;
+    free(lm->data);
+    free(lm);
+}
+
+void pxl8_lightmap_clear(pxl8_lightmap* lm, u8 r, u8 g, u8 b) {
+    if (!lm || !lm->data) return;
+    u32 count = lm->width * lm->height;
+    for (u32 i = 0; i < count; i++) {
+        lm->data[i * 3 + 0] = r;
+        lm->data[i * 3 + 1] = g;
+        lm->data[i * 3 + 2] = b;
+    }
+}
+
+void pxl8_lightmap_set(pxl8_lightmap* lm, u32 x, u32 y, u8 r, u8 g, u8 b) {
+    if (!lm || !lm->data || x >= lm->width || y >= lm->height) return;
+    u32 idx = (y * lm->width + x) * 3;
+    lm->data[idx + 0] = r;
+    lm->data[idx + 1] = g;
+    lm->data[idx + 2] = b;
+}
+
+void pxl8_lightmap_get(const pxl8_lightmap* lm, u32 x, u32 y, u8* r, u8* g, u8* b) {
+    if (!lm || !lm->data || x >= lm->width || y >= lm->height) {
+        *r = *g = *b = PXL8_LIGHTMAP_NEUTRAL;
+        return;
+    }
+    u32 idx = (y * lm->width + x) * 3;
+    *r = lm->data[idx + 0];
+    *g = lm->data[idx + 1];
+    *b = lm->data[idx + 2];
+}
+
+void pxl8_lightmap_add_point(
+    pxl8_lightmap* lm,
+    f32 lx, f32 ly,
+    u8 r, u8 g, u8 b,
+    f32 radius,
+    f32 intensity
+) {
+    if (!lm || !lm->data || radius <= 0.0f) return;
+
+    f32 radius_sq = radius * radius;
+    f32 inv_radius_sq = 1.0f / radius_sq;
+
+    i32 cx = (i32)(lx * (f32)lm->width);
+    i32 cy = (i32)(ly * (f32)lm->height);
+    i32 rad_pixels = (i32)(radius * (f32)lm->width) + 1;
+
+    i32 x0 = cx - rad_pixels;
+    i32 y0 = cy - rad_pixels;
+    i32 x1 = cx + rad_pixels;
+    i32 y1 = cy + rad_pixels;
+
+    if (x0 < 0) x0 = 0;
+    if (y0 < 0) y0 = 0;
+    if (x1 >= (i32)lm->width) x1 = (i32)lm->width - 1;
+    if (y1 >= (i32)lm->height) y1 = (i32)lm->height - 1;
+
+    f32 scale_x = 1.0f / (f32)lm->width;
+    f32 scale_y = 1.0f / (f32)lm->height;
+
+    for (i32 y = y0; y <= y1; y++) {
+        f32 dy = ((f32)y * scale_y) - ly;
+        for (i32 x = x0; x <= x1; x++) {
+            f32 dx = ((f32)x * scale_x) - lx;
+            f32 dist_sq = dx * dx + dy * dy;
+
+            if (dist_sq >= radius_sq) continue;
+
+            f32 falloff = 1.0f - dist_sq * inv_radius_sq;
+            f32 contrib = falloff * falloff * intensity;
+
+            u32 idx = ((u32)y * lm->width + (u32)x) * 3;
+
+            i32 nr = (i32)lm->data[idx + 0] + (i32)((f32)(r - 128) * contrib);
+            i32 ng = (i32)lm->data[idx + 1] + (i32)((f32)(g - 128) * contrib);
+            i32 nb = (i32)lm->data[idx + 2] + (i32)((f32)(b - 128) * contrib);
+
+            if (nr < 0) nr = 0; if (nr > 255) nr = 255;
+            if (ng < 0) ng = 0; if (ng > 255) ng = 255;
+            if (nb < 0) nb = 0; if (nb > 255) nb = 255;
+
+            lm->data[idx + 0] = (u8)nr;
+            lm->data[idx + 1] = (u8)ng;
+            lm->data[idx + 2] = (u8)nb;
+        }
+    }
+}