fragment-shader

I'm trying to provide access to a 3-dimensional array of scalar data to a fragment shader, from a Python program using PyOpenGL. In the fragment shader, I declare the a 3d sampler uniform uniform sampler3D vol; and in the Python program I have the following code to set up a scalar 3d texture vol = numpy.random.rand(3, 3, 3).astype(np.float32) texture = glGenTextures(1) glUniform1i(glGetUniformLocation(program, "vol"), 0) glActiveTexture(GL_TEXTURE0 + 0) glBindTexture(GL_TEXTURE_3D, texture) glTexImage3D(GL_TEXTURE_3D, 0, GL_RED, 3, 3, 3, 0, GL_RED, GL_FLOAT, vol) glEnable(GL_TEXTURE_3D)

I must do a homework and I try to implement a lookAt function. I tried in many ways but the only result I got is a blue screen. The rest of my program works greatly, infact if I use glm::lookAt all is good. This is my code: mat4 Transform::lookAt(const vec3 &eye, const vec3 &center, const vec3 &up) { vec3 w(glm::normalize(eye - center)) ; vec3 u(glm::normalize(glm::cross(up, w))); vec3 v(glm::cross(w, u)) ; mat4 ret = mat4 ( vec4 (u.x,v.x,w.x,0), vec4 (u.y,v.y,w.y,0), vec4 (u.z,v.z,w.z,0), vec4 (-u.x*eye.x-u.y*eye.y-u.z*eye.z, -v.x*eye.x-v.y*eye.y-v.z*eye.z, -w.x*eye.x-w.y*eye.y-w.z*eye.z, 1)

I'm using the normal shader in three.js r.58, which I understand requires a normal map . However, I'm using a dynamic displacement map, so a pre-computed normal map won't work in this situation. All the examples I've found of lit displacement maps either use flat shading or pre-computed normal maps. Is it possible to calculate the normals dynamically based on the displaced vertices instead? Edit: I've posted a demo of a sphere with a displacement map showing flat normals : Here's a link to the github repo with all of my examples illustrating this problem, and the solutions I eventually found:

I just want to store an array of weights that needs to every fragment calculation. This: float weights[5] = float[5](3.4, 4.2, 5.0, 5.2, 1.1); Just throws this: ERROR: 0:30: ']' : syntax error syntax error ERROR: 0:30: ';' : syntax error syntax error Stefan Hanke From the OpenGL ES SL 1.0 spec , paragraph 4.1.9 Arrays (p. 24): There is no mechanism for initializing arrays at declaration time from within a shader. Note that this has been intentionally left out . According to this post , the OpenGL ES SL version for OpenGL ES 2 is based on OpenGL SL 1.2 . The same paragraph (p. 20) contains:

I want to adjust the colors depending on which xyz position they are in the world. I tried this in my fragment shader: varying vec4 verpos; void main(){ vec4 c; c.x = verpos.x; c.y = verpos.y; c.z = verpos.z; c.w = 1.0; gl_FragColor = c; } but it seems that the colors change depending on my camera angle/position, how do i make the coords independent from my camera position/angle? Heres my vertex shader: varying vec4 verpos; void main(){ gl_Position = ftransform(); verpos = gl_ModelViewMatrix*gl_Vertex; } Edit2: changed title, so i want world coords, not screen coords! Edit3: added my full code

Right now I am trying to pass an array of ints into the fragment shader, and am doing this through a uniform array: uniform int myArray[300]; And filling it outside the shader with glUniform1iv . Unfortunately, uniform arrays larger than ~400 fail. I understand that I can use a "uniform buffer" instead, but can't seem to a find a full example of passing a large 1D array into a fragment shader with buffers or otherwise. Could anyone supply such an example? This should get you started using a Uniform Buffer Object to store an array. Note that GL requires UBOs to have a minimum capacity of 16 KiB