Try to solve task 2.2

exercise2/glsl/terrain.frag

@@ -3,6 +3,8 @@
 // chair of the TU Dresden. Do not distribute!
 // Copyright (C) CGV TU Dresden - All Rights Reserved
 
+in vec3 n;
+
 out vec4 color;
 
 uniform vec3 cameraPos;
@@ -31,7 +33,7 @@ vec4 getBackgroundColor()
 void main()
 {
 	//surface geometry
-	vec3 n = vec3(0, 1, 0);
+	//vec3 n = vec3(0, 1, 0);
 	vec3 dirToViewer = vec3(0, 1, 0);
 
 	//material properties

exercise2/glsl/terrain.vert

@@ -5,18 +5,31 @@
 
 in vec4 position;
 
-
+out vec3 n;
 
 uniform mat4 mvp;
 
 //Returns the height of the procedural terrain at a given xz position
 float getTerrainHeight(vec2 p);
 
+vec3 calculate_normal(vec4 terrain_position);
+vec4 offset_point(vec4 base, vec2 offset);
 
+const vec2 offsets[6] = vec2[6](
+	vec2(0.0, 0.0),
+	vec2(0.0, 1.0),
+	vec2(1.0, 0.0),
+	vec2(0.0, 1.0),
+	vec2(1.0, 0.0),
+	vec2(1.0, 1.0)
+);
 
 void main()
 {
-	gl_Position = mvp * position;
+	vec4 terrain_position = vec4(position.x, getTerrainHeight(vec2(position.x, position.z)), position.z, position.w);
+	n = calculate_normal(position);
+
+	gl_Position = mvp * terrain_position;
 }
 
 //source: https://gist.github.com/patriciogonzalezvivo/670c22f3966e662d2f83
@@ -56,3 +69,49 @@ float getTerrainHeight(vec2 p)
 	}
 	return 15 * total / maxAmplitude;
 }
+
+vec4 offset_point(vec4 base, vec2 offset) {
+	float y = getTerrainHeight(vec2(base.x, base.z) + offset);
+	return vec4(base.x + offset.x, y, base.z + offset.y, base.w);
+}
+
+// calculate the position of the first vertex in this square
+vec4 pos_to_base(vec4 pos, int v_id) {
+	return vec4(pos.x - offsets[v_id].x, pos.y, pos.z - offsets[v_id].y, pos.w);
+}
+
+// calculates the normal of terrain_position
+// it generates the complete triangle based on the gl_VertexID and then normal math
+vec3 calculate_normal(vec4 terrain_position) {
+	int offset_index = gl_VertexID % 6;
+
+	vec4 base_vertex = pos_to_base(terrain_position, offset_index);
+
+	// the other 2 points from the triangle
+	int points_index = 0;
+	vec4 points[2];
+
+	int iterator_offset = 0;
+
+	// second triangle offset
+	if (offset_index > 2) {
+		iterator_offset = 3;
+	}
+
+	for (int i = iterator_offset; i < (3 + iterator_offset); i++) {
+		// skip for current vertex
+		if (i == offset_index) {
+			continue;
+		}
+
+		points[points_index] = offset_point(base_vertex, offsets[i]);
+		points_index++;
+	}
+
+	// create connection vectors
+	vec3 p1 = (points[0] - terrain_position).xyz;
+	vec3 p2 = (points[1] - terrain_position).xyz;
+
+	// calculate normal
+	return normalize(cross(p1, p2));
+}

exercise2/src/Viewer.cpp

@@ -112,8 +112,10 @@ void Viewer::CreateGeometry()
 	/*Generate positions and indices for a terrain patch with a
 	  single triangle strip */
 
-	for (int i = 0; i < PATCH_SIZE; i++) {
-		for (int j = 0; j < PATCH_SIZE; j++) {
+	for (int i = 0; i < PATCH_SIZE; i++)
+	{
+		for (int j = 0; j < PATCH_SIZE; j++)
+		{
 			positions.emplace_back((float)i, 0.0f, (float)j, 1.0f);
 		}
 	}
@@ -122,12 +124,14 @@ void Viewer::CreateGeometry()
 	// decrease y direction by 1
 	int count = (PATCH_SIZE) * (PATCH_SIZE - 1);
 
-	for (int k = 0; k < count; k++) {
+	for (int k = 0; k < count; k++)
+	{
 
 		// skip creating triangles on last x in row
 		int end_of_x = k % (PATCH_SIZE - 1);
 
-		if (end_of_x == 0) {
+		if (end_of_x == 0)
+		{
 			continue;
 		}
 
@@ -194,8 +198,7 @@ void CalculateViewFrustum(const Eigen::Matrix4f& mvp, Eigen::Vector4f* frustumPl
 
 bool IsBoxCompletelyBehindPlane(const Eigen::Vector3f &boxMin, const Eigen::Vector3f &boxMax, const Eigen::Vector4f &plane)
 {
-	return
-		plane.dot(Eigen::Vector4f(boxMin.x(), boxMin.y(), boxMin.z(), 1)) < 0 &&
+	return plane.dot(Eigen::Vector4f(boxMin.x(), boxMin.y(), boxMin.z(), 1)) < 0 &&
 		   plane.dot(Eigen::Vector4f(boxMin.x(), boxMin.y(), boxMax.z(), 1)) < 0 &&
 		   plane.dot(Eigen::Vector4f(boxMin.x(), boxMax.y(), boxMin.z(), 1)) < 0 &&
 		   plane.dot(Eigen::Vector4f(boxMin.x(), boxMax.y(), boxMin.z(), 1)) < 0 &&
@@ -225,7 +228,7 @@ void Viewer::drawContents()
 	terrainShader.setUniform("cameraPos", cameraPosition, false);
 
 	/* Task: Render the terrain */
-	//glPrimitiveRestartIndex(255);
+	glPrimitiveRestartIndex(512);
 	glDrawElements(GL_TRIANGLE_STRIP, (PATCH_SIZE - 1) * (PATCH_SIZE - 1) * 4, GL_UNSIGNED_INT, 0);
 
 	//Render text