Fix issues with environment mapping

2 files changed, 126 insertions, 22 deletions

diff --git a/drivers/gles3/shaders/cubemap_filter.glsl b/drivers/gles3/shaders/cubemap_filter.glsl
index 619e29b130..d83a109cb9 100644
--- a/drivers/gles3/shaders/cubemap_filter.glsl
+++ b/drivers/gles3/shaders/cubemap_filter.glsl
@@ -30,12 +30,22 @@ uniform sampler2DArray source_dual_paraboloid_array; //texunit:0
 uniform int source_array_index;
 #endif
 
-#if !defined(USE_SOURCE_DUAL_PARABOLOID_ARRAY) && !defined(USE_SOURCE_PANORAMA)
+#ifdef USE_SOURCE_DUAL_PARABOLOID
+uniform sampler2D source_dual_paraboloid; //texunit:0
+#endif
+
+#if defined(USE_SOURCE_DUAL_PARABOLOID) || defined(COMPUTE_IRRADIANCE)
+uniform int source_mip_level;
+#endif
+
+#if !defined(USE_SOURCE_DUAL_PARABOLOID_ARRAY) && !defined(USE_SOURCE_PANORAMA) && !defined(USE_SOURCE_DUAL_PARABOLOID)
 uniform samplerCube source_cube; //texunit:0
 #endif
 
 uniform int face_id;
 uniform float roughness;
+uniform float source_resolution;
+
 in highp vec2 uv_interp;
 
 layout(location = 0) out vec4 frag_color;
@@ -133,6 +143,19 @@ vec3 ImportanceSampleGGX(vec2 Xi, float Roughness, vec3 N) {
 	return TangentX * H.x + TangentY * H.y + N * H.z;
 }
 
+float DistributionGGX(vec3 N, vec3 H, float roughness) {
+	float a = roughness * roughness;
+	float a2 = a * a;
+	float NdotH = max(dot(N, H), 0.0);
+	float NdotH2 = NdotH * NdotH;
+
+	float nom = a2;
+	float denom = (NdotH2 * (a2 - 1.0) + 1.0);
+	denom = M_PI * denom * denom;
+
+	return nom / denom;
+}
+
 // http://graphicrants.blogspot.com.au/2013/08/specular-brdf-reference.html
 float GGX(float NdotV, float a) {
 	float k = a / 2.0;
@@ -160,10 +183,12 @@ vec2 Hammersley(uint i, uint N) {
 #ifdef LOW_QUALITY
 
 #define SAMPLE_COUNT 64u
+#define SAMPLE_DELTA 0.05
 
 #else
 
-#define SAMPLE_COUNT 1024u
+#define SAMPLE_COUNT 512u
+#define SAMPLE_DELTA 0.01
 
 #endif
 
@@ -171,7 +196,7 @@ uniform bool z_flip;
 
 #ifdef USE_SOURCE_PANORAMA
 
-vec4 texturePanorama(vec3 normal, sampler2D pano) {
+vec4 texturePanorama(vec3 normal, sampler2D pano, float mipLevel) {
 
 	vec2 st = vec2(
 			atan(normal.x, normal.z),
@@ -182,7 +207,7 @@ vec4 texturePanorama(vec3 normal, sampler2D pano) {
 
 	st /= vec2(M_PI * 2.0, M_PI);
 
-	return textureLod(pano, st, 0.0);
+	return textureLod(pano, st, mipLevel);
 }
 
 #endif
@@ -202,6 +227,20 @@ vec4 textureDualParaboloidArray(vec3 normal) {
 
 #endif
 
+#ifdef USE_SOURCE_DUAL_PARABOLOID
+vec4 textureDualParaboloid(vec3 normal) {
+
+	vec3 norm = normalize(normal);
+	norm.xy /= 1.0 + abs(norm.z);
+	norm.xy = norm.xy * vec2(0.5, 0.25) + vec2(0.5, 0.25);
+	if (norm.z < 0.0) {
+		norm.y = 0.5 - norm.y + 0.5;
+	}
+	return textureLod(source_dual_paraboloid, norm.xy, float(source_mip_level));
+}
+
+#endif
+
 void main() {
 
 #ifdef USE_DUAL_PARABOLOID
@@ -225,7 +264,7 @@ void main() {
 
 #ifdef USE_SOURCE_PANORAMA
 
-	frag_color = vec4(texturePanorama(N, source_panorama).rgb, 1.0);
+	frag_color = vec4(texturePanorama(N, source_panorama, 0.0).rgb, 1.0);
 #endif
 
 #ifdef USE_SOURCE_DUAL_PARABOLOID_ARRAY
@@ -233,12 +272,51 @@ void main() {
 	frag_color = vec4(textureDualParaboloidArray(N).rgb, 1.0);
 #endif
 
-#if !defined(USE_SOURCE_DUAL_PARABOLOID_ARRAY) && !defined(USE_SOURCE_PANORAMA)
+#ifdef USE_SOURCE_DUAL_PARABOLOID
+
+	frag_color = vec4(textureDualParaboloid(N).rgb, 1.0);
+#endif
+
+#if !defined(USE_SOURCE_DUAL_PARABOLOID_ARRAY) && !defined(USE_SOURCE_PANORAMA) && !defined(USE_SOURCE_DUAL_PARABOLOID)
 
 	N.y = -N.y;
 	frag_color = vec4(texture(N, source_cube).rgb, 1.0);
 #endif
 
+#else // USE_DIRECT_WRITE
+
+#ifdef COMPUTE_IRRADIANCE
+
+	vec3 irradiance = vec3(0.0);
+
+	// tangent space calculation from origin point
+	vec3 UpVector = vec3(0.0, 1.0, 0.0);
+	vec3 TangentX = cross(UpVector, N);
+	vec3 TangentY = cross(N, TangentX);
+
+	float num_samples = 0.0f;
+
+	for (float phi = 0.0; phi < 2.0 * M_PI; phi += SAMPLE_DELTA) {
+		for (float theta = 0.0; theta < 0.5 * M_PI; theta += SAMPLE_DELTA) {
+			// Calculate sample positions
+			vec3 tangentSample = vec3(sin(theta) * cos(phi), sin(theta) * sin(phi), cos(theta));
+			// Find world vector of sample position
+			vec3 H = tangentSample.x * TangentX + tangentSample.y * TangentY + tangentSample.z * N;
+
+			vec2 st = vec2(atan(H.x, H.z), acos(H.y));
+			if (st.x < 0.0) {
+				st.x += M_PI * 2.0;
+			}
+			st /= vec2(M_PI * 2.0, M_PI);
+
+			irradiance += texture(source_panorama, st, source_mip_level).rgb * cos(theta) * sin(theta);
+			num_samples++;
+		}
+	}
+	irradiance = M_PI * irradiance * (1.0 / float(num_samples));
+
+	frag_color = vec4(irradiance, 1.0);
+
 #else
 
 	vec4 sum = vec4(0.0, 0.0, 0.0, 0.0);
@@ -246,15 +324,26 @@ void main() {
 	for (uint sampleNum = 0u; sampleNum < SAMPLE_COUNT; sampleNum++) {
 		vec2 xi = Hammersley(sampleNum, SAMPLE_COUNT);
 
-		vec3 H = ImportanceSampleGGX(xi, roughness, N);
+		vec3 H = normalize(ImportanceSampleGGX(xi, roughness, N));
 		vec3 V = N;
-		vec3 L = (2.0 * dot(V, H) * H - V);
+		vec3 L = normalize(2.0 * dot(V, H) * H - V);
 
-		float ndotl = clamp(dot(N, L), 0.0, 1.0);
+		float ndotl = max(dot(N, L), 0.0);
 
 		if (ndotl > 0.0) {
+
+			float D = DistributionGGX(N, H, roughness);
+			float ndoth = max(dot(N, H), 0.0);
+			float hdotv = max(dot(H, V), 0.0);
+			float pdf = D * ndoth / (4.0 * hdotv) + 0.0001;
+
+			float saTexel = 4.0 * M_PI / (6.0 * source_resolution * source_resolution);
+			float saSample = 1.0 / (float(SAMPLE_COUNT) * pdf + 0.0001);
+
+			float mipLevel = roughness == 0.0 ? 0.0 : 0.5 * log2(saSample / saTexel);
+
 #ifdef USE_SOURCE_PANORAMA
-			sum.rgb += texturePanorama(L, source_panorama).rgb * ndotl;
+			sum.rgb += texturePanorama(L, source_panorama, mipLevel).rgb * ndotl;
 #endif
 
 #ifdef USE_SOURCE_DUAL_PARABOLOID_ARRAY
@@ -262,7 +351,12 @@ void main() {
 			sum.rgb += textureDualParaboloidArray(L).rgb * ndotl;
 #endif
 
-#if !defined(USE_SOURCE_DUAL_PARABOLOID_ARRAY) && !defined(USE_SOURCE_PANORAMA)
+#ifdef USE_SOURCE_DUAL_PARABOLOID
+
+			sum.rgb += textureDualParaboloid(L).rgb * ndotl;
+#endif
+
+#if !defined(USE_SOURCE_DUAL_PARABOLOID_ARRAY) && !defined(USE_SOURCE_PANORAMA) && !defined(USE_SOURCE_DUAL_PARABOLOID)
 			L.y = -L.y;
 			sum.rgb += textureLod(source_cube, L, 0.0).rgb * ndotl;
 #endif
@@ -273,5 +367,6 @@ void main() {
 
 	frag_color = vec4(sum.rgb, 1.0);
 
-#endif
+#endif // COMPUTE_IRRADIANCE
+#endif // USE_DIRECT_WRITE
 }
diff --git a/drivers/gles3/shaders/scene.glsl b/drivers/gles3/shaders/scene.glsl
index 403de25dd0..e1b0e9f595 100644
--- a/drivers/gles3/shaders/scene.glsl
+++ b/drivers/gles3/shaders/scene.glsl
@@ -627,6 +627,8 @@ layout(std140) uniform Radiance { // ubo:2
 
 #define RADIANCE_MAX_LOD 5.0
 
+uniform sampler2D irradiance_map; // texunit:-6
+
 #ifdef USE_RADIANCE_MAP_ARRAY
 
 uniform sampler2DArray radiance_map; // texunit:-2
@@ -1766,6 +1768,11 @@ FRAGMENT_SHADER_CODE
 
 	vec3 eye_vec = view;
 
+	// IBL precalculations
+	float ndotv = clamp(dot(normal, eye_vec), 0.0, 1.0);
+	vec3 f0 = F0(metallic, specular, albedo);
+	vec3 F = f0 + (max(vec3(1.0 - roughness), f0) - f0) * pow(1.0 - ndotv, 5.0);
+
 #ifdef USE_RADIANCE_MAP
 
 #ifdef AMBIENT_LIGHT_DISABLED
@@ -1775,22 +1782,27 @@ FRAGMENT_SHADER_CODE
 
 		{ //read radiance from dual paraboloid
 
-			vec3 ref_vec = reflect(-eye_vec, normal); //2.0 * ndotv * normal - view; // reflect(v, n);
+			vec3 ref_vec = reflect(-eye_vec, normal);
 			ref_vec = normalize((radiance_inverse_xform * vec4(ref_vec, 0.0)).xyz);
 			vec3 radiance = textureDualParaboloid(radiance_map, ref_vec, roughness) * bg_energy;
 			env_reflection_light = radiance;
 		}
-		//no longer a cubemap
-		//vec3 radiance = textureLod(radiance_cube, r, lod).xyz * ( brdf.x + brdf.y);
 	}
 #ifndef USE_LIGHTMAP
 	{
 
-		vec3 ambient_dir = normalize((radiance_inverse_xform * vec4(normal, 0.0)).xyz);
-		vec3 env_ambient = textureDualParaboloid(radiance_map, ambient_dir, 1.0) * bg_energy;
+		vec3 norm = normal;
+		norm = normalize((radiance_inverse_xform * vec4(norm, 0.0)).xyz);
+		norm.xy /= 1.0 + abs(norm.z);
+		norm.xy = norm.xy * vec2(0.5, 0.25) + vec2(0.5, 0.25);
+		if (norm.z > 0.0) {
+			norm.y = 0.5 - norm.y + 0.5;
+		}
+
+		vec3 env_ambient = texture(irradiance_map, norm.xy).rgb * bg_energy;
+		env_ambient *= 1.0 - F;
 
 		ambient_light = mix(ambient_light_color.rgb, env_ambient, radiance_ambient_contribution);
-		//ambient_light=vec3(0.0,0.0,0.0);
 	}
 #endif
 #endif //AMBIENT_LIGHT_DISABLED
@@ -1892,12 +1904,9 @@ FRAGMENT_SHADER_CODE
 		const vec4 c0 = vec4(-1.0, -0.0275, -0.572, 0.022);
 		const vec4 c1 = vec4(1.0, 0.0425, 1.04, -0.04);
 		vec4 r = roughness * c0 + c1;
-		float ndotv = clamp(dot(normal, eye_vec), 0.0, 1.0);
 		float a004 = min(r.x * r.x, exp2(-9.28 * ndotv)) * r.x + r.y;
 		vec2 env = vec2(-1.04, 1.04) * a004 + r.zw;
-
-		vec3 f0 = F0(metallic, specular, albedo);
-		specular_light *= env.x * f0 + env.y;
+		specular_light *= env.x * F + env.y;
 #endif
 	}