Refactor

shaders/tessellation_eval.glsl

@@ -5,7 +5,8 @@ layout(quads, fractional_even_spacing, cw) in;
 layout(binding = 0) uniform sampler2D heightTexture;
 layout(location = 0) uniform mat4 M;
 
-uniform float displacementScale = 0.05;
+uniform float displacementScale = 0.1f;
+uniform float tessellationFactor;
 
 layout(std140, binding = 0) uniform SceneUniforms
 {
@@ -25,33 +26,24 @@ out TE_OUT {
 } te_out;
 
 float getHeight(vec2 uv) {
-    return texture(heightTexture, uv).r;
+    return texture(heightTexture, uv).r * displacementScale;
 }
 
-vec3 calculateFaceNormal(vec3 p1, vec3 p2, vec3 p3) {
-    return normalize(cross(p2 - p1, p3 - p1));
+vec3 calculateSmoothNormal(vec3 pos, vec2 coord) {
+    float step = 1.0f / (tessellationFactor + 1.0f);
+
+    float hLeft = getHeight(coord + vec2(-step, 0.0f));
+    float hRight = getHeight(coord + vec2(step, 0.0f));
+    float hUp = getHeight(coord + vec2(0.0f, step));
+    float hDown = getHeight(coord + vec2(0.0f, -step));
+    
+    vec3 tangentX = normalize(vec3(step, hRight - hLeft, 0.0));
+    vec3 tangentY = normalize(vec3(0.0, hUp - hDown, step));
+
+    return normalize(cross(tangentY, tangentX));
 }
 
 void main() {
-    vec3 barycentricCoords = gl_TessCoord;
-
-    vec3 p0 = te_in[0].position;
-    vec3 p1 = te_in[1].position;
-    vec3 p2 = te_in[2].position;
-    vec3 displacedPosition = barycentricCoords.x * p0 + barycentricCoords.y * p1 + barycentricCoords.z * p2;
-
-    float displacement = texture(heightTexture, vec2(displacedPosition.x, displacedPosition.z)).r * displacementScale;
-
-    //te_out.position = vec4(displacedPosition, 1.0f).xyz;
-
-    vec3 dp1 = p1 - p0;
-    vec3 dp2 = p2 - p0;
-
-    dp1.z += texture(heightTexture, vec2(p1.x, p1.y)).r * displacementScale - texture(heightTexture, vec2(p0.x, p0.y)).r * displacementScale;
-    dp2.z += texture(heightTexture, vec2(p2.x, p2.y)).r * displacementScale - texture(heightTexture, vec2(p0.x, p0.y)).r * displacementScale;
-
-    te_out.normal = normalize(cross(dp1, dp2));
-
     // Interpolate texture coordinates
     vec2 texCoord = mix(
         mix(te_in[0].texCoord, te_in[1].texCoord, gl_TessCoord[0]),
@@ -68,24 +60,8 @@ void main() {
 
     position.z += texture(heightTexture, texCoord).r * displacementScale;
 
-    // // Calculate normals based on the tessellated triangle's vertices
-    // vec3 p0 = gl_in[0].gl_Position.xyz;
-    // vec3 p1 = gl_in[1].gl_Position.xyz;
-    // vec3 p2 = gl_in[2].gl_Position.xyz;
-
-    // vec3 n_u = p1 - p0;
-    // vec3 v_u = p2 - p0;
-    // vec3 v_normal = normalize(cross(n_u, v_u));
-
-    // // Calculate normals for the specific triangle being rendered
-    // vec3 normal = calculateFaceNormal(p0, p1, position);
-    // normal += calculateFaceNormal(p1, p2, position);
-    // normal += calculateFaceNormal(p2, p0, position);
-
-    // normal = (PV*M*vec4(normalize(normal), 1.0f)).xyz;
-
-    te_out.position = (PV*M*vec4(position, 1.0f)).xyz;
+    te_out.position = (M*vec4(position, 1.0f)).xyz; // Position in world-space
     te_out.texCoord = texCoord;
-    //te_out.normal = (PV*M*vec4(v_normal, 1.0f)).xyz;
-    gl_Position = PV*M*vec4(position, 1.0f);
+    te_out.normal   = calculateSmoothNormal(position, texCoord);  
+    gl_Position = PV*M*vec4(position, 1.0f);        // Position in screen-space
 }