From 77f9dbee1721518e09f0beed10b3dbb78d893b08 Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Fri, 13 Feb 2026 10:27:58 -0800
Subject: Ambient lighting. Defer texture filtering

---
 src/swgfx.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/swgfx.c b/src/swgfx.c
index d41b69d..ddd64f7 100644
--- a/src/swgfx.c
+++ b/src/swgfx.c
@@ -45,6 +45,7 @@ typedef struct swgfx {
   R*            depth;     // Depth  buffer.
   sgTextureId*  texture;   // Texture ID buffer.
   sgVec2*       texcoords; // Texture coords buffer.
+  sgPixel*      albedo;    // Albedo buffer.
   sgViewport_t  viewport;
   sgMat4        model;     // Model matrix.
   sgMat4        view;      // View matrix.
@@ -89,6 +90,7 @@ static inline sgVec2  mod2(sgVec2 v, R m) { return (sgVec2){mod1(v.x, m), mod1(v
 static inline sgVec3 add3(sgVec3 a, sgVec3 b) { return (sgVec3){a.x + b.x, a.y + b.y, a.z + b.z}; }
 static inline sgVec3 neg3(sgVec3 v) { return (sgVec3){-v.x, -v.y, -v.z}; }
 static inline sgVec3 sub3(sgVec3 a, sgVec3 b) { return (sgVec3){a.x - b.x, a.y - b.y, a.z - b.z}; }
+static inline sgVec3 mul3(sgVec3 a, sgVec3 b) { return (sgVec3){a.x * b.x, a.y * b.y, a.z * b.z}; }
 static inline sgVec3 div3(sgVec3 a, sgVec3 b) { return (sgVec3){a.x / b.x, a.y / b.y, a.z / b.z}; }
 static inline sgVec3 scale3(sgVec3 v, R s) { return (sgVec3){v.x * s, v.y * s, v.z * s}; }
 static inline sgVec3 exp3(sgVec3 v, R exp) { return (sgVec3){powf(v.x, exp), powf(v.y, exp), powf(v.z, exp)};}
@@ -739,6 +741,7 @@ size_t sgMem(int width, int height) {
          Align(N * sizeof(R)) +           // Depth buffer.
          Align(N * sizeof(sgTextureId)) + // Texture ID buffer.
          Align(N * sizeof(sgVec2)) +      // Texture coords buffer.
+         Align(N * sizeof(sgPixel)) +     // Albedo buffer.
          Align(SWGFX_TEXTURE_REGISTER_SIZE * sizeof(sgTexture)) + // Texture register.
          (SG_ALIGN - 1); // To make room to align allocations within the buffer.
 }
@@ -752,6 +755,7 @@ swgfx* sgNew(int width, int height, void* mem) {
   gfx->depth     = SG_ALLOC(&aligned, N, R);
   gfx->texture   = SG_ALLOC(&aligned, N, sgTextureId);
   gfx->texcoords = SG_ALLOC(&aligned, N, sgVec2);
+  gfx->albedo    = SG_ALLOC(&aligned, N, sgPixel);
   gfx->textureRegister = SG_ALLOC(&aligned, SWGFX_TEXTURE_REGISTER_SIZE, sgTexture);
   gfx->activeTexture = DefaultTextureId;
   gfx->defaultPixel  = (sgPixel){255, 255, 255, 255};
@@ -973,10 +977,21 @@ void sgLighting(swgfx* gfx) {
       const sgTextureId texid  = gfx->texture[i];
       const sgTexture* texture = &gfx->textureRegister[texid];
       const sgVec2 uv          = gfx->texcoords[i];
-      sgPixel* colour          = &gfx->colour[i];
-      // TODO: Actual lighting.
-      const sgPixel albedo = Sample(texture->image, texture->filter, uv);
-      *colour = albedo;
+      sgPixel* albedo          = &gfx->albedo[i];
+      *albedo = Sample(texture->image, texture->filter, uv);
+    }
+  }
+}
+
+void sgAmbient(swgfx* gfx, sgVec3 ambient) {
+  assert(gfx);
+  const int N = gfx->dims.x * gfx->dims.y;
+  for (int i = 0; i < N; ++i) {
+    const R depth = gfx->depth[i];
+    if (depth != DepthClearValue) {
+      const sgPixel* albedo = &gfx->albedo[i];
+      sgPixel* colour       = &gfx->colour[i];
+      *colour = Vec3ToPixel(mul3(PixelToVec3(*albedo), ambient), (R)albedo->a/255.f);
     }
   }
 }
-- 
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