shader: adding gamma correction (#60)

marsp0 · Jan 2, 2025 · 97b6129 · 97b6129
1 parent 670b76a
commit 97b6129
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Showing 3 changed files with 48 additions and 28 deletions.
diff --git a/src/math.c b/src/math.c
@@ -252,6 +252,15 @@ vec4_t vec4_scale_with_w(vec4_t v, float scale)
     return res;
 }
 
+vec4_t vec4_pow(vec4_t v, float pow)
+{
+    v.x = f_pow(v.x, pow);
+    v.y = f_pow(v.y, pow);
+    v.z = f_pow(v.z, pow);
+
+    return v;
+}
+
 vec4_t vec4_negate(vec4_t v)
 {
     return vec4_new(-v.x, -v.y, -v.z);
@@ -585,26 +594,6 @@ float f_max(float a, float b)
     return a > b ? a : b;
 }
 
-int32_t i_max(int32_t a, int32_t b)
-{
-    return a > b ? a : b;
-}
-
-int32_t i_min(int32_t a, int32_t b)
-{
-    return a < b ? a : b;
-}
-
-uint32_t u_max(uint32_t a, uint32_t b)
-{
-    return a > b ? a : b;
-}
-
-uint32_t u_min(uint32_t a, uint32_t b)
-{
-    return a < b ? a : b;
-}
-
 float f_clamp(float v, float min, float max)
 {
     return f_min(max, f_max(min, v));
@@ -651,3 +640,28 @@ float f_round(float v)
 {
     return roundf(v);
 }
+
+float f_pow(float v, float pow)
+{
+    return powf(v, pow);
+}
+
+int32_t i_max(int32_t a, int32_t b)
+{
+    return a > b ? a : b;
+}
+
+int32_t i_min(int32_t a, int32_t b)
+{
+    return a < b ? a : b;
+}
+
+uint32_t u_max(uint32_t a, uint32_t b)
+{
+    return a > b ? a : b;
+}
+
+uint32_t u_min(uint32_t a, uint32_t b)
+{
+    return a < b ? a : b;
+}
diff --git a/src/math.h b/src/math.h
@@ -76,6 +76,7 @@ vec4_t      vec4_sub(vec4_t v1, vec4_t v2);
 vec4_t      vec4_cross(vec4_t v1, vec4_t v2);
 vec4_t      vec4_scale(vec4_t v, float scale);
 vec4_t      vec4_scale_with_w(vec4_t v, float scale);
+vec4_t      vec4_pow(vec4_t v, float pow);
 vec4_t      vec4_negate(vec4_t v);
 vec4_t      vec4_normalize(vec4_t v);
 vec4_t      vec4_hadamard(vec4_t v1, vec4_t v2);
@@ -170,11 +171,12 @@ float       f_max(float a, float b);
 float       f_ceil(float v);
 float       f_floor(float v);
 float       f_round(float v);
-int32_t     i_max(int32_t a, int32_t b);
-int32_t     i_min(int32_t a, int32_t b);
-uint32_t    u_max(uint32_t a, uint32_t b);
-uint32_t    u_min(uint32_t a, uint32_t b);
 float       f_clamp(float v, float min, float max);
 float       f_wrap(float v, float min, float max);
 float       f_sin(float v);
 float       f_cos(float v);
+float       f_pow(float v, float pow);
+int32_t     i_max(int32_t a, int32_t b);
+int32_t     i_min(int32_t a, int32_t b);
+uint32_t    u_max(uint32_t a, uint32_t b);
+uint32_t    u_min(uint32_t a, uint32_t b);
diff --git a/src/shader.c b/src/shader.c
@@ -24,11 +24,12 @@
 /* static variables */
 /********************/
 
+static const float gamma_val        = 2.2f;
+static const float one_over_gamma   = 1.f / gamma_val;
 static camera_t* camera             = NULL;
 static texture_t* albedo_texture    = NULL;
 static texture_t* metallic_texture  = NULL;
 static texture_t* normal_texture    = NULL;
-// static mat_t  tbn_t_w;
 static vec4_t v0_w;
 static vec4_t v1_w;
 static vec4_t v2_w;
@@ -179,7 +180,7 @@ uint32_t shader_fragment(float w0, float w1, float w2)
     float s             = f_min(t0.x * w0 + t1.x * w1 + t2.x * w2, 1.f);
     float t             = f_min(t0.y * w0 + t1.y * w1 + t2.y * w2, 1.f);
 
-    vec4_t albedo       = vec4_scale(texture_sample(albedo_texture, s, t), 2.2f);
+    vec4_t albedo       = vec4_pow(texture_sample(albedo_texture, s, t), gamma_val);
     vec4_t metallic     = texture_sample(metallic_texture, s, t);
     float rough         = metallic.y;                                       // green channel
     float metal         = metallic.x;                                       // blue channel
@@ -247,7 +248,10 @@ uint32_t shader_fragment(float w0, float w1, float w2)
     col                 = vec4_scale(col, 1.f);
     col                 = vec4_scale(col, n_dot_l);
 
-    vec4_t ambient = vec4_scale(albedo, 0.1f);
+    // ambient + gamma correction
 
-    return vec4_to_bgra(vec4_add(col, ambient));
+    vec4_t ambient      = vec4_scale(albedo, 0.1f);
+    vec4_t final        = vec4_pow(vec4_add(col, ambient), one_over_gamma);
+
+    return vec4_to_bgra(final);
 }