From d44df852bbdcb58d634413d69eaa288a7b4573f3 Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Thu, 5 Feb 2026 17:16:39 -0800
Subject: Expose texture filter.

---
 include/swgfx.h |  7 ++++++-
 src/swgfx.c     | 28 ++++++++++++++++------------
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/include/swgfx.h b/include/swgfx.h
index cdeefe8..e9e69b8 100644
--- a/include/swgfx.h
+++ b/include/swgfx.h
@@ -53,6 +53,11 @@ typedef sgRgba sgPixel;
 // TODO: Expose a macro to control the desired surface format.
 typedef sgBgra sgScreenPixel;
 
+typedef enum sgTextureFilter {
+  sgNearest,
+  sgBilinear
+} sgTextureFilter;
+
 typedef struct sgImage {
   int      width;
   int      height;
@@ -76,7 +81,7 @@ void sgOrtho      (swgfx*, R left, R right, R top, R bottom, R near, R far);
 void sgPerspective(swgfx*, R fovy, R aspect, R near, R far);
 void sgViewport   (swgfx*, int x0, int y0, int width, int height);
 
-void sgTexture(swgfx*, const sgImage*);
+void sgTexture(swgfx*, const sgImage*, sgTextureFilter);
 
 void sgClear(swgfx*);
 void sgPixels(swgfx*, size_t count, const sgVec2i* positions, sgPixel colour);
diff --git a/src/swgfx.c b/src/swgfx.c
index 85844e0..153a5f4 100644
--- a/src/swgfx.c
+++ b/src/swgfx.c
@@ -44,11 +44,12 @@ typedef struct swgfx {
   // Make it so that changing the model matrix only requires one matrix
   // multiplication (mvp = model * viewProj) and not two (mvp = model * view * projection)
   // before rendering the model's triangles.
-  sgMat4         viewProj;       // View-projection matrix.
-  sgMat4         mvp;            // Model-view-projection matrix.
-  const sgImage* texture;        // User-specified texture.
-  sgImage        defaultTexture; // A default for when no texture is provided.
-  sgPixel        defaultPixel;   // The single-pixel of the default texture.
+  sgMat4          viewProj;       // View-projection matrix.
+  sgMat4          mvp;            // Model-view-projection matrix.
+  const sgImage*  texture;        // User-specified texture.
+  sgTextureFilter textureFilter;  // Filter method for the texture.
+  sgImage         defaultTexture; // A default for when no texture is provided.
+  sgPixel         defaultPixel;   // The single-pixel of the default texture.
 } swgfx;
 
 static inline int mod(int a, int m) { return (m + (a % m)) % m; }
@@ -359,10 +360,12 @@ static inline sgPixel FilterBilinear(const sgImage* texture, sgVec2 uv) {
 
 // TODO: Mipmapping.
 // TODO: Clamping and other addressing strategies.
-static inline sgPixel Sample(const sgImage* texture, sgVec2 uv) {
-  // TODO: Add a member to sgImage that determines how it should be filtered.
-  //return FilterNearest(texture, uv);
-  return FilterBilinear(texture, uv);
+static inline sgPixel Sample(const sgImage* texture, sgTextureFilter filter, sgVec2 uv) {
+  switch (filter) {
+  case sgNearest: return FilterNearest(texture, uv);
+  case sgBilinear: return FilterBilinear(texture, uv);
+  default: assert(false); return (sgPixel){0};
+  }
 }
 
 static inline sgAABB2 TriangleAabb2(sgVec2 p0, sgVec2 p1, sgVec2 p2) {
@@ -433,7 +436,7 @@ static void DrawTriangle2(swgfx* gfx, const sgTri2* const tri) {
       if ((bar.x >= 0) && (bar.y >= 0) && (bar.z >= 0)) {
         assert((bar.x + bar.y + bar.z - 1e7) <= 1.f);
         const sgVec2 uv = BarycentricInterp2(bar, tri->p0.uv, tri->p1.uv, tri->p2.uv);
-        const sgPixel colour = Sample(gfx->texture, uv);
+        const sgPixel colour = Sample(gfx->texture, gfx->textureFilter, uv);
         SetPixel(gfx, (sgVec2i){x,y}, colour);
       }
     }
@@ -644,7 +647,7 @@ static void DrawTriangle3PostClip(swgfx* gfx, const sgTri4* const tri) {
         R* depth = Depth(gfx, x, y);
         if ((0.f <= p_depth) && (p_depth <= 1.f) && (p_depth <= *depth)) {
           *depth = p_depth;
-          const sgPixel colour = Sample(gfx->texture, uv);
+          const sgPixel colour = Sample(gfx->texture, gfx->textureFilter, uv);
           // TODO: When doing lighting, need to tone-map here and apply inverse
           //  gamma here.
           //const sgPixel colour = {(uint8_t)(bar.x*255.f), (uint8_t)(bar.y*255.f), (uint8_t)(bar.z*255.f), 255};
@@ -800,10 +803,11 @@ void sgViewport(swgfx* gfx, int x0, int y0, int width, int height) {
   gfx->viewport = (sgViewport_t){x0, y0, width, height};
 }
 
-void sgTexture(swgfx* gfx, const sgImage* texture) {
+void sgTexture(swgfx* gfx, const sgImage* texture, sgTextureFilter filter) {
   assert(gfx);
   assert(texture);
   gfx->texture = texture;
+  gfx->textureFilter = filter;
 }
 
 void sgClear(swgfx* gfx) {
-- 
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