normals

I want to find normals for height map data. I am using gl_triangles in my code for indices. How would I find normals for this? Given a triangle (vert1, vert2, vert3) its normal is ((vert2 - vert1).cross(vert3 - vert1)).normalize() . For smooth, per-vertex normals: Foreach vertex, sum together the face normals for each triangle that vertex is a part of, then normalize the sum. EDIT : Example: #include <GL/glut.h> #include <vector> #include <cmath> #include <Eigen/Core> #include <Eigen/Geometry> using namespace std; using namespace Eigen; typedef Matrix< Vector3f, Dynamic, Dynamic > VecMat; //

I'm attempting to hack and modify several rendering features of an old opengl fixed pipeline game, by hooking into OpenGl calls, and my current mission is to implement shader lighting. I've already created an appropriate shader program that lights most of my objects correctly, but this game's terrain is drawn with no normal data provided. The game calls: void glVertexPointer(GLint size, GLenum type, GLsizei stride, const GLvoid * pointer); and void glDrawElements(GLenum mode, GLsizei count, GLenum type, const GLvoid * indices);` to define and draw the terrain, thus I have these functions both

I've written a C++ Obj file loader that I can't get to work correctly. The problem is that while parsing a simple obj file like the following: # Blender v2.62 (sub 0) OBJ File: '' # www.blender.org mtllib cube.mtl o Cube v 1.000000 -1.000000 -1.000000 v 1.000000 -1.000000 1.000000 v -1.000000 -1.000000 1.000000 v -1.000000 -1.000000 -1.000000 v 1.000000 1.000000 -0.999999 v 0.999999 1.000000 1.000001 v -1.000000 1.000000 1.000000 v -1.000000 1.000000 -1.000000 vn 0.000000 0.000000 -1.000000 vn -1.000000 -0.000000 -0.000000 vn -0.000000 -0.000000 1.000000 vn 1.000000 -0.000000 0.000000 vn 1

I have a scene with several models with individual positions and rotations. Given normals, the shaders apply simple bidirectional lighting to each pixel. That is my vertex shader. #version 150 in vec3 position; in vec3 normal; in vec2 texcoord; out vec3 f_normal; out vec2 f_texcoord; uniform mat4 model; uniform mat4 view; uniform mat4 proj; void main() { mat4 mvp = proj * view * model; f_normal = normal; f_texcoord = texcoord; gl_Position = mvp * vec4(position, 1.0); } And here is the fragment shader. #version 150 in vec3 f_normal; in vec2 f_texcoord; uniform sampler2D tex; vec3 sun = vec3(0.5

I'm generating terrain in Opengl geometry shader and am having trouble calculating normals for lighting. I'm generating the terrain dynamically each frame with a perlin noise function implemented in the geometry shader. Because of this, I need an efficient way to calculate normals per-vertex based on the noise function (no texture or anything). I am able to take cross product of 2 side to get face normals, but they are generated dynamically with the geometry so I cannot then go back and smooth the face normals for vertex normals. How can I get vertex normals on the fly just using the noise

I am doing the following to try and estimate surface normals from a point cloud generated from a Kinect depth image: pcl::PointCloud<pcl::PointXYZRGB>::Ptr create_point_cloud_ptr(Mat& depthImage, Mat& rgbImage){ pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZRGB>()); cloud->width = depthImage.rows; //Dimensions must be initialized to use 2-D indexing cloud->height = depthImage.cols; cloud->resize(cloud->width*cloud->height); int min_depth = INT_MAX; int num_of_points_added = 0; for(int v=0; v< depthImage.rows; v++){ //2-D indexing for(int u=0; u< depthImage.cols;

Given a convex polyhedron with defined vertices (x, y, z) that specifies the faces of the polyhedron. How can I go about calculating the surface normal of each face of the polyhedron? I need the surface normal in order to compute the vertex normal to perform Gouraud shading . The only clue I could find about how to do this is Newell's method, but how do I make sure the normals are outward normals and not inward? Thanks for any help. Compute the face normal You have to compute the cross product of two vectors spanning the plane that contains the given face. It gives you the (non-unit) normal

I heard that I should use normals instead of colors, because colors are deprecated. (Is that true?) Normals have something to do with the reflection of light, but I can't find a clear and intuitive explanation. What is a normal? A normal in general is a unit vector whose direction is perpendicular to a surface at a specific point. Therefore it tells you in which direction a surface is facing. The main use case for normals are lighting calculations, where you have to determine the angle (or practically often its cosine) between the normal at a given surface point and the direction towards a