Add shader diffuse multiply

shaders/light_common.glsl

@@ -256,17 +256,29 @@ vec3 EnvBRDFApprox(vec3 F0, float roughness, float NoV)
     return F0 * AB.x + AB.y;
 }
 
+// Diffuse colour of the submodel (t3d/e3d) or shape, used as the albedo multiplier:
+// untextured materials take it as their colour, textured ones multiply the base texture by it
+// (same as the legacy renderer's GL_MODULATE). param[0].rgb holds the authored sRGB colour,
+// param[1].x its intensity (HSV value unless a material overrides it).
+vec3 material_diffuse()
+{
+    vec3 diffusecolor = pow(max(param[0].rgb, vec3(0.0)), vec3(2.2));
+    float value = max(param[0].r, max(param[0].g, param[0].b));
+    return (value > 0.0 ? diffusecolor * (param[1].x / value) : vec3(0.0));
+}
+
 // [0] - diffuse, [1] - specular
 // do magic here
 vec3 apply_lights(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, float reflectivity, float specularity, float shadowtone)
 {
-    vec3 basecolor = param[0].rgb;
+    // Diffuse colour is applied once, to the albedo; the light terms below are not scaled by it again
-    // Scale ambient before it gets tinted by basecolor / texture.
+    texturecolor *= material_diffuse();
+    // Scale ambient before it gets tinted by the 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;
+    fragcolor *= AMBIENT_SCALE;
 
-    vec3 emissioncolor = basecolor * emission;
+    vec3 emissioncolor = vec3(emission);
 
     vec3 view_dir = normalize(-f_pos.xyz);
     float NdotV = max(dot(fragnormal, view_dir), 0.0);
@@ -302,7 +314,7 @@ vec3 apply_lights(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, float refl
     // panels, vehicle bodies and terrain reads as a clear edge rather
     // 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 diffuseamount = sun_NdotL * lights[0].intensity;
 
     float shadow1 = 0.0;
     if (shadowtone < 1.0)
@@ -317,7 +329,7 @@ vec3 apply_lights(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, float refl
     {
         light_s light = lights[i];
         vec2 part = calc_headlights(light, fragnormal);
-        fragcolor += light.color * (part.x * param[1].x + part.y * param[1].y) * light.intensity;
+        fragcolor += light.color * (part.x + part.y * param[1].y) * light.intensity;
     }
 
     float specularamount = sunlight.y * param[1].y * specularity * lights[0].intensity

shaders/mat_colored.frag

@@ -24,7 +24,8 @@ layout(location = 1) out vec4 out_motion;
 
 void main()
 {
-	vec4 tex_color = vec4(pow(param[0].rgb, vec3(2.2)), param[0].a);
+	// no texture: the diffuse colour alone makes the albedo, apply_lights() applies it to the white base
+	vec4 tex_color = vec4(1.0, 1.0, 1.0, param[0].a);
 
 //	if (tex_color.a < opacity)
 //		discard;
@@ -32,7 +33,7 @@ void main()
 	vec3 fragcolor = ambient;
 	vec3 fragnormal = normalize(f_normal);
 	float reflectivity = param[1].z;
-	float specularity = (tex_color.r + tex_color.g + tex_color.b) * 0.5;
+	float specularity = dot(pow(param[0].rgb, vec3(2.2)), vec3(0.5));
 	glossiness = abs(param[1].w);
 	
 	fragcolor = apply_lights(fragcolor, fragnormal, tex_color.rgb, reflectivity, specularity, shadow_tone);

shaders/mat_sunlessnormalmap.frag

@@ -32,14 +32,15 @@ uniform sampler2D normalmap;
 
 vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, float reflectivity, float specularity, float shadowtone)
 {
-	vec3 basecolor = param[0].rgb;
+	// diffuse colour applied once, to the albedo (see material_diffuse() in light_common.glsl)
+	texturecolor *= material_diffuse();
 
 	// 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;
+	fragcolor *= 0.80;
 
-	vec3 emissioncolor = basecolor * emission;
+	vec3 emissioncolor = vec3(emission);
 	vec3 envcolor = envmap_color(fragnormal);
 
 // yuv path
@@ -60,7 +61,7 @@ vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, fl
 	// Sharpen N.L for stronger contrast between lit and shaded cab
 	// 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 diffuseamount = sun_NdotL * lights[0].intensity;
 	fragcolor += envcolor * reflectivity;
 	float specularamount = (sunlight.y * param[1].y * specularity) * lights[0].intensity;
 	glossiness = abs(param[1].w);
@@ -79,7 +80,7 @@ vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, fl
 //		else if (light.type == LIGHT_HEADLIGHTS)
 			part = calc_headlights(light, fragnormal);
 
-		fragcolor += light.color * (part.x * param[1].x + part.y * param[1].y) * light.intensity;
+		fragcolor += light.color * (part.x + part.y * param[1].y) * light.intensity;
 	}
 
 	if (shadowtone < 1.0)

shaders/mat_sunlessnormalmap_specgloss.frag

@@ -36,12 +36,13 @@ uniform sampler2D specgloss;
 
 vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, float reflectivity, float specularity, float shadowtone)
 {
-    vec3 basecolor = param[0].rgb;
+    // diffuse colour applied once, to the albedo (see material_diffuse() in light_common.glsl)
+    texturecolor *= material_diffuse();
     // 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;
+    fragcolor *= 0.80;
 
-    vec3 emissioncolor = basecolor * emission;
+    vec3 emissioncolor = vec3(emission);
 
     vec3 view_dir = normalize(-f_pos.xyz);
     float NdotV = max(dot(fragnormal, view_dir), 0.0);
@@ -71,7 +72,7 @@ vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, fl
     // Sharpen N.L for stronger contrast between lit and shaded cab
     // 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 diffuseamount = sun_NdotL * lights[0].intensity;
 
     float specularamount = sunlight.y * param[1].y * specularity * lights[0].intensity;
 
@@ -79,7 +80,7 @@ vec3 apply_lights_sunless(vec3 fragcolor, vec3 fragnormal, vec3 texturecolor, fl
     {
         light_s light = lights[i];
         vec2 part = calc_headlights(light, fragnormal);
-        fragcolor += light.color * (part.x * param[1].x + part.y * param[1].y) * light.intensity;
+        fragcolor += light.color * (part.x + part.y * param[1].y) * light.intensity;
     }
 
     if (shadowtone < 1.0)