improve shaders once more

shaders/light_common.glsl

@@ -10,6 +10,27 @@ uniform sampler2D headlightmap;
 float glossiness = 1.0;
 float metalic = 0.0;
 
+// ---------------------------------------------------------------------
+// Lighting balance tunables - tweak these to control overall scene
+// exposure without touching tonemapping.glsl.
+//
+// AMBIENT_SCALE:        brightness of SHADED faces (indirect/sky term).
+//                       Lower -> deeper shadows, less burn under bright
+//                       textures. Higher -> flatter / brighter shading.
+//
+// SUN_DIFFUSE_SCALE:    brightness of UNSHADED (sun-lit) faces. Lower
+//                       this to dim hot surfaces in direct sunlight
+//                       without affecting shaded areas. Was 3.5; 2.5
+//                       calmly fits the ACES tonemap shoulder.
+//
+// SUN_NDOTL_SHARPNESS:  N.L curve on the sun. 1.0 = pure Lambert, higher
+//                       = sharper terminator (more contrast between
+//                       lit and shaded faces of the same surface).
+// ---------------------------------------------------------------------
+const float AMBIENT_SCALE       = 0.65;
+const float SUN_DIFFUSE_SCALE   = 2.5;
+const float SUN_NDOTL_SHARPNESS = 1.25;
+
 float length2(vec3 v)
 {
         return dot(v, v);
@@ -135,7 +156,10 @@ vec2 calc_headlights(light_s light, vec3 fragnormal)
 vec3 apply_lights(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, float reflectivity, float specularity, float shadowtone)
 {
     vec3 basecolor = param[0].rgb;
-    fragcolor *= basecolor;
+    // Scale ambient before it gets tinted by basecolor / texture.
+    // Sun, headlights and emission are added afterwards so they are NOT
+    // attenuated by AMBIENT_SCALE - this only dims the indirect term.
+    fragcolor *= basecolor * AMBIENT_SCALE;
 
     vec3 emissioncolor = basecolor * emission;
 
@@ -161,19 +185,18 @@ vec3 apply_lights(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, float refl
     vec2 sunlight = calc_dir_light(lights[0], fragnormal);
     // Sharpen sun N.L falloff so the lit-to-shaded terminator on cab
     // panels, vehicle bodies and terrain reads as a clear edge rather
-    // than a soft Lambertian ramp. Stays close to physical Lambert.
-    float sun_NdotL = pow(sunlight.x, 1.25);
+    // than a soft Lambertian ramp. Tunable via SUN_NDOTL_SHARPNESS.
+    float sun_NdotL = pow(sunlight.x, SUN_NDOTL_SHARPNESS);
     float diffuseamount = sun_NdotL * param[1].x * lights[0].intensity;
 
     float shadow1 = 0.0;
     if (shadowtone < 1.0)
         shadow1 = (1.0 - shadowtone) * clamp(calc_shadow(), 0.0, 1.0);
 
-    // Sun HDR scale lowered from 5.0 -> 3.5: with the previous broken
-    // identity-Reinhard tonemap the 5x boost just clipped at 1.0; with
-    // ACES tonemapping in place 3.5 keeps lit areas strong but leaves
-    // real headroom for spec highlights instead of crushing to white.
-    fragcolor += lights[0].color * 3.5 * (1.0 - shadow1) * diffuseamount;
+    // Sun HDR scale -> SUN_DIFFUSE_SCALE (default 2.5). Controls how
+    // bright sun-lit (unshaded) faces get. Lower this if surfaces in
+    // direct sun read as too hot/burnt; raise it for more punch.
+    fragcolor += lights[0].color * SUN_DIFFUSE_SCALE * (1.0 - shadow1) * diffuseamount;
 
     for (uint i = 1U; i < lights_count; i++)
     {

shaders/mat_sunlessnormalmap.frag

@@ -34,7 +34,10 @@ vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, fl
 {
 	vec3 basecolor = param[0].rgb;
 
-	fragcolor *= basecolor;
+	// Cab interior: dim ambient less than the exterior path because
+	// ambient is the dominant indoor illumination. 0.80 trims the
+	// brightest faces without making the cab feel under-lit.
+	fragcolor *= basecolor * 0.80;
 
 	vec3 emissioncolor = basecolor * emission;
 	vec3 envcolor = envmap_color(fragnormal);
@@ -55,8 +58,8 @@ vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, fl
 	vec2 sunlight = calc_dir_light(lights[0], fragnormal);
 
 	// Sharpen N.L for stronger contrast between lit and shaded cab
-	// surfaces (matches light_common.glsl apply_lights).
-	float sun_NdotL = pow(sunlight.x, 1.25);
+	// surfaces (uses SUN_NDOTL_SHARPNESS from light_common.glsl).
+	float sun_NdotL = pow(sunlight.x, SUN_NDOTL_SHARPNESS);
 	float diffuseamount = (sun_NdotL * param[1].x) * lights[0].intensity;
 	fragcolor += envcolor * reflectivity;
 	float specularamount = (sunlight.y * param[1].y * specularity) * lights[0].intensity;

shaders/mat_sunlessnormalmap_specgloss.frag

@@ -37,7 +37,9 @@ uniform sampler2D specgloss;
 vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, float reflectivity, float specularity, float shadowtone)
 {
     vec3 basecolor = param[0].rgb;
-    fragcolor *= basecolor;
+    // Cab interior: dim ambient less than the exterior path - ambient
+    // is the dominant indoor illumination, but it was still too bright.
+    fragcolor *= basecolor * 0.80;
 
     vec3 emissioncolor = basecolor * emission;
 
@@ -61,8 +63,8 @@ vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, fl
 
     vec2 sunlight = calc_dir_light(lights[0], fragnormal);
     // Sharpen N.L for stronger contrast between lit and shaded cab
-    // surfaces (matches light_common.glsl apply_lights).
-    float sun_NdotL = pow(sunlight.x, 1.25);
+    // surfaces (uses SUN_NDOTL_SHARPNESS from light_common.glsl).
+    float sun_NdotL = pow(sunlight.x, SUN_NDOTL_SHARPNESS);
     float diffuseamount = sun_NdotL * param[1].x * lights[0].intensity;
 
     float specularamount = sunlight.y * param[1].y * specularity * lights[0].intensity;

shaders/tonemapping.glsl

@@ -47,5 +47,5 @@ vec4 tonemap(vec4 x)
 	// just clips HDR>1.0 at the framebuffer -> washed-out / burnt look.
 	// ACES gives a smooth highlight shoulder + slight toe contrast.
 	return FBOUT(vec4(ACESFilm(x.rgb), x.a));
-//	return FBOUT(vec4(reinhard(x.rgb), x.a));
+	//return FBOUT(vec4(reinhard(x.rgb), x.a));
 }