From b1c966b47df257d88579db395fba4fe9484bfdc8 Mon Sep 17 00:00:00 2001
From: Warwick <warwick.l.e.new@gmail.com>
Date: Fri, 29 Jul 2022 13:01:01 +0100
Subject: [PATCH] Adding a limit to the number of primitves exiting my geometry
 shader stops the shape from breaking...

---
 data/shaders/geometry.glsl    | 41 +++++++++++++++++++++++++----------
 data/shaders/pbrFragment.glsl | 34 ++++++++++++++++++++++-------
 2 files changed, 55 insertions(+), 20 deletions(-)

diff --git a/data/shaders/geometry.glsl b/data/shaders/geometry.glsl
index 49a76b0..44df27d 100644
--- a/data/shaders/geometry.glsl
+++ b/data/shaders/geometry.glsl
@@ -1,6 +1,6 @@
 #version 330 core
 layout (triangles) in;
-layout (triangle_strip) out;
+layout (triangle_strip, max_vertices = 3) out;
 
 uniform mat4 Model;
 
@@ -12,7 +12,16 @@ out vec2 texCoord;
 out vec3 normCoord;
 out vec3 WorldPos;
 
-out mat3 TBN;
+vec3 lightPosition = vec3(1, 1, 2);
+
+uniform vec3 CameraPos;
+
+out GS_OUT {
+   mat3 TBN;
+   vec3 tangentLightPos;
+   vec3 tangentViewPos;
+   vec3 tangentFragPos;
+} gs_out;
 
 void main(void)
 {
@@ -38,20 +47,24 @@ void main(void)
    // [ddTxBxTyByTzBz]=1ΔU1ΔV2−ΔU2ΔV1[ΔV2−ΔU2−ΔV1ΔU1][E1xE2xE1yE2yE1zE2z]
    // https://learnopengl.com/Advanced-Lighting/Normal-Mapping
 
-   float f = 1.0 / (duv1.x * duv2.y - duv2.x * duv1.y);
+   float invDet = 1.0 / (duv1.x * duv2.y - duv2.x * duv1.y);
 
-   float tx = f * (duv2.y * edge1.x - duv1.y * edge2.x);
-   float ty = f * (duv2.y * edge1.y - duv1.y * edge2.y);
-   float tz = f * (duv2.y * edge1.z - duv1.y * edge2.z);
-
-   vec3 tangent = vec3(tx, ty, tz);
+   vec3 tangent = vec3 (invDet * (duv2.y * edge1 - duv1.y * edge2));
+   vec3 bitangent = vec3 (invDet * (-duv2.x * edge1 - duv1.x * edge2));
 
    //Calculate TBN
-   vec3 T = normalize(vec3(Model * vec4(tangent, 0.0)));
-   vec3 N = normalize(vec3(Model * vec4(gnormCoord[0], 0.0)));
-   vec3 B = cross(N, T);
+   //mat3 normalMatrix = transpose(inverse(mat3(Model)));
 
-   TBN = mat3(T, B, N);
+   vec3 T = normalize(vec3(Model * vec4(tangent, 0.0f)));
+   vec3 B = normalize(vec3(Model * vec4(bitangent, 0.0f)));
+   vec3 N = normalize(vec3(Model * vec4(cross(edge2, edge1), 0.0f)));
+
+   mat3 TBN = transpose(mat3(T, B, N));
+   gs_out.TBN = TBN;
+
+   gs_out.tangentLightPos = TBN * lightPosition;
+   gs_out.tangentViewPos = TBN * CameraPos;
+   gs_out.tangentFragPos = TBN * gWorldPos[0];
 
    // send data to Fragment Shader
    gl_Position = gl_in[0].gl_Position;
@@ -64,12 +77,16 @@ void main(void)
    texCoord = gtexCoord[1];
    normCoord = gnormCoord[1];
    WorldPos = gWorldPos[1];
+
+   gs_out.tangentFragPos = TBN * gWorldPos[1];
    EmitVertex();
 
    gl_Position = gl_in[2].gl_Position;
    texCoord = gtexCoord[2];
    normCoord = gnormCoord[2];
    WorldPos = gWorldPos[2];
+
+   gs_out.tangentFragPos = TBN * gWorldPos[2];
    EmitVertex();
    EndPrimitive();
 };
diff --git a/data/shaders/pbrFragment.glsl b/data/shaders/pbrFragment.glsl
index 2bb1f3b..ffd14bb 100644
--- a/data/shaders/pbrFragment.glsl
+++ b/data/shaders/pbrFragment.glsl
@@ -4,6 +4,14 @@ out vec4 FragColor;
 in vec2 texCoord;
 in vec3 normCoord;
 in vec3 WorldPos;
+
+in GS_OUT {
+   mat3 TBN;
+   vec3 tangentLightPos;
+   vec3 tangentViewPos;
+   vec3 tangentFragPos;
+} from_gs;
+
 in mat3 TBN;
 
 // TODO: make temporary hard coded world/camera pos dynamic
@@ -71,27 +79,34 @@ float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness)
    return ggx1 * ggx2;
 }
 
-vec3 normal(){
+vec3 normalMapNormal(){
    // load and invert normal
-   vec3 normal = texture(texture_normal1, texCoord).rgb * 2.0 - 1.0;
-   normal = normalize(TBN * normal);
+   vec3 normal = normalize(texture(texture_normal1, texCoord).rgb * 2.0 - 1.0);
 
-   return normal;
+   vec3 lightDir = normalize(from_gs.tangentLightPos - from_gs.tangentFragPos);
+   vec3 viewDir  = normalize(from_gs.tangentViewPos - from_gs.tangentFragPos);
+   vec3 reflectDir = reflect(-lightDir, normal);
+   vec3 halfwayDir = normalize(lightDir + viewDir);
+   float spec = pow(max(dot(normal, halfwayDir), 0.0),32.0);
+
+   vec3 normMapSpecular = vec3(0.2) * spec;
+
+   return normMapSpecular;
 }
 
 
 vec3 PBR(vec3 albedo, float roughness, float metallic, float ao)
 {
    // Establish a temporary hard coded light position
-   vec3 lightPosition = vec3( 1,  1, 2);
+   vec3 lightPosition = vec3(1, 1, 2);
    //vec3 lightPosition = vec3( (sin(tick / 1000.0)*2),  1 + sin(tick / 600.0)*2, 2.0);
    //vec3 lightColor = vec3(1.0, 1.0, 1.0) - sin(tick / 90);
    vec3 lightColor  = vec3(13.47, 11.31, 10.79);
 
    vec3 N = normalize(normCoord);
    vec3 V = normalize(CameraPos - WorldPos);
-   //N = (N + normal()) / 2;
-   //N = normal(); //For seeing if normal map tracks with light.
+   //N = (N + normalMapNormal()) / 2;
+   //N = normalMapNormal(); //For seeing if normal map tracks with light.
 
    vec3 F0 = vec3(0.04);
    F0 = mix(F0, albedo, metallic);
@@ -140,5 +155,8 @@ void main()
    float ao = texture(texture_rma1, texCoord).b;
 
    //FragColor = vec4(PBR(albedo, roughness, metallic, ao), 1.0);
-   FragColor = vec4(normal(), 1.0);
+   FragColor = vec4(PBR(albedo, roughness, metallic, ao) + normalMapNormal(), 1.0);
+   //FragColor = vec4(normalMapNormal(), 1.0);
+   //FragColor = vec4(vec3(0.5) + normalMapNormal(), 1.0);
+   //FragColor = vec4(vec3(0.5), 1.0);
 }