• Advertisement
Sign in to follow this  

OpenGL GLSL projective shadows Solved :) stupid mistake :(

This topic is 2965 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi everybody. I am new to OpenGL and I am also new here and this is my first post. I am from Slovakia and my English is not that great, but I hope you will understand what I am writing (sorry for mistakes) I have got a problem with shadow mapping implementation using GLSL. Everything works fine using glTexGeni with GL_EYE_LINEAR. I generate my shadow map, transform it and bind to texture. Problem is multitexturing because I have nvidia card which supports only 4 active texture units (also another pass for rendering shadowed area - on ATI I used GL_TEXTURE_COMPARE_FAIL_VALUE_ARB ) and I want to use diffuse map and normal map on model so only 2 remain for shadows and of course I want to use more shadows for some scenes. So my way leads to GLSL. I read a lot of tutorials and forums but I did not find good explanation for this. So far I was able to texture objects using GLSL and combine it with another textures. My real problem is projective shadow texture. In my current code I am using: glTexGenfv(GL_S, GL_EYE_PLANE, &(textureMatrix[0])); glTexGenfv(GL_T, GL_EYE_PLANE, &(textureMatrix[4])); glTexGenfv(GL_R, GL_EYE_PLANE, &(textureMatrix[8])); glTexGenfv(GL_Q, GL_EYE_PLANE, &(textureMatrix[12])); and as you can see my textureMatrix is matrix generated by translating->multiplying->transposing etc model view and projection matrix of my active light. Before I render my scene I activate texture unit, use glTexGenfv for shadow texture and disable mapping(I will enable it later in rendering) for active lights and everything works great. If I try to send this texture unit to my shader, my texture projection is not working well. What I need to know is how to perform this texgen operation for my projective texture for GLSL, if there is any equivalent for this function or some matrix operations. I already found some tuts for EYE_LINEAR mapping but I was unable to successfully implement it. I will really appreciate any hint. Thanks for replies Stanley [Edited by - SaTANO on January 8, 2010 6:06:25 PM]

Share this post


Link to post
Share on other sites
Advertisement
Thanks V-man
I was out for a while (NEW YEAR and some semestral exams) and after I read the post I find out that there must be problem somewhere else and tried different approach. For many people works simple formula bias*lightProjection*lightModelView. I think the problem is somewhere in my matrixe. I am changing modelview matrix every time i am rendering object (cameraModelView translated rotated scaled to rendered object position). In Fabien Sanglard tutorial of shadow mapping I saw that when he is translating modelview matrix to object he is also translating texture matrix with same values. So first problem was here

As you said I need to transform each vertex from camera space to eye space. So its matrix only operations and I think this should works but its not

load bias=> multiply light projection => multiply light modelview => Scale Translate Rotate

In shader I should be able to use

gl_TextureMatrix[2] * gl_Vertex; // I stored light matrix to texture2

What I think is correct. I tried to project shadow map from camera to see if my shader works correctly so I used gl_ModelViewProjectionMatrix * gl_Vertex and switch my camera to position of light and it works.
There must be problem in my matrix.

I would like to know if there is some additional operation for shadowtexture matrix.

[Edited by - SaTANO on January 8, 2010 6:11:31 PM]

Share this post


Link to post
Share on other sites
Punch me
Problem solved
I was making 3 different algorithms to calculate matrix and every one was right
After 2 weeks of researching, reading books/forums/tutorials, spamming my friend I found problem
Guess what
I was sending matrix to my function and store it (I used only pointer) and do matrix magic on them (for texgen operation). But what I forget is after I make this, I changed my matrix so I was multiplying already multiplied matrix. It was really strange when I send same matrix to shader but I have got different results so I decide to print this matrix and saw that "What Am I stupid?"
And this stupid thing cost me 2 weeks

So it works like charm

[Edited by - SaTANO on January 8, 2010 6:59:13 PM]

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
  • Advertisement
  • Popular Tags

  • Advertisement
  • Popular Now

  • Similar Content

    • By LifeArtist
      Good Evening,
      I want to make a 2D game which involves displaying some debug information. Especially for collision, enemy sights and so on ...
      First of I was thinking about all those shapes which I need will need for debugging purposes: circles, rectangles, lines, polygons.
      I am really stucked right now because of the fundamental question:
      Where do I store my vertices positions for each line (object)? Currently I am not using a model matrix because I am using orthographic projection and set the final position within the VBO. That means that if I add a new line I would have to expand the "points" array and re-upload (recall glBufferData) it every time. The other method would be to use a model matrix and a fixed vbo for a line but it would be also messy to exactly create a line from (0,0) to (100,20) calculating the rotation and scale to make it fit.
      If I proceed with option 1 "updating the array each frame" I was thinking of having 4 draw calls every frame for the lines vao, polygons vao and so on. 
      In addition to that I am planning to use some sort of ECS based architecture. So the other question would be:
      Should I treat those debug objects as entities/components?
      For me it would make sense to treat them as entities but that's creates a new issue with the previous array approach because it would have for example a transform and render component. A special render component for debug objects (no texture etc) ... For me the transform component is also just a matrix but how would I then define a line?
      Treating them as components would'nt be a good idea in my eyes because then I would always need an entity. Well entity is just an id !? So maybe its a component?
      Regards,
      LifeArtist
    • By QQemka
      Hello. I am coding a small thingy in my spare time. All i want to achieve is to load a heightmap (as the lowest possible walking terrain), some static meshes (elements of the environment) and a dynamic character (meaning i can move, collide with heightmap/static meshes and hold a varying item in a hand ). Got a bunch of questions, or rather problems i can't find solution to myself. Nearly all are deal with graphics/gpu, not the coding part. My c++ is on high enough level.
      Let's go:
      Heightmap - i obviously want it to be textured, size is hardcoded to 256x256 squares. I can't have one huge texture stretched over entire terrain cause every pixel would be enormous. Thats why i decided to use 2 specified textures. First will be a tileset consisting of 16 square tiles (u v range from 0 to 0.25 for first tile and so on) and second a 256x256 buffer with 0-15 value representing index of the tile from tileset for every heigtmap square. Problem is, how do i blend the edges nicely and make some computationally cheap changes so its not obvious there are only 16 tiles? Is it possible to generate such terrain with some existing program?
      Collisions - i want to use bounding sphere and aabb. But should i store them for a model or entity instance? Meaning i have 20 same trees spawned using the same tree model, but every entity got its own transformation (position, scale etc). Storing collision component per instance grats faster access + is precalculated and transformed (takes additional memory, but who cares?), so i stick with this, right? What should i do if object is dynamically rotated? The aabb is no longer aligned and calculating per vertex min/max everytime object rotates/scales is pretty expensive, right?
      Drawing aabb - problem similar to above (storing aabb data per instance or model). This time in my opinion per model is enough since every instance also does not have own vertex buffer but uses the shared one (so 20 trees share reference to one tree model). So rendering aabb is about taking the model's aabb, transforming with instance matrix and voila. What about aabb vertex buffer (this is more of a cosmetic question, just curious, bumped onto it in time of writing this). Is it better to make it as 8 points and index buffer (12 lines), or only 2 vertices with min/max x/y/z and having the shaders dynamically generate 6 other vertices and draw the box? Or maybe there should be just ONE 1x1x1 cube box template moved/scaled per entity?
      What if one model got a diffuse texture and a normal map, and other has only diffuse? Should i pass some bool flag to shader with that info, or just assume that my game supports only diffuse maps without fancy stuff?
      There were several more but i forgot/solved them at time of writing
      Thanks in advance
    • By RenanRR
      Hi All,
      I'm reading the tutorials from learnOpengl site (nice site) and I'm having a question on the camera (https://learnopengl.com/Getting-started/Camera).
      I always saw the camera being manipulated with the lookat, but in tutorial I saw the camera being changed through the MVP arrays, which do not seem to be camera, but rather the scene that changes:
      Vertex Shader:
      #version 330 core layout (location = 0) in vec3 aPos; layout (location = 1) in vec2 aTexCoord; out vec2 TexCoord; uniform mat4 model; uniform mat4 view; uniform mat4 projection; void main() { gl_Position = projection * view * model * vec4(aPos, 1.0f); TexCoord = vec2(aTexCoord.x, aTexCoord.y); } then, the matrix manipulated:
      ..... glm::mat4 projection = glm::perspective(glm::radians(fov), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f); ourShader.setMat4("projection", projection); .... glm::mat4 view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp); ourShader.setMat4("view", view); .... model = glm::rotate(model, glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f)); ourShader.setMat4("model", model);  
      So, some doubts:
      - Why use it like that?
      - Is it okay to manipulate the camera that way?
      -in this way, are not the vertex's positions that changes instead of the camera?
      - I need to pass MVP to all shaders of object in my scenes ?
       
      What it seems, is that the camera stands still and the scenery that changes...
      it's right?
       
       
      Thank you
       
    • By dpadam450
      Sampling a floating point texture where the alpha channel holds 4-bytes of packed data into the float. I don't know how to cast the raw memory to treat it as an integer so I can perform bit-shifting operations.

      int rgbValue = int(textureSample.w);//4 bytes of data packed as color
      // algorithm might not be correct and endianness might need switching.
      vec3 extractedData = vec3(  rgbValue & 0xFF000000,  (rgbValue << 8) & 0xFF000000, (rgbValue << 16) & 0xFF000000);
      extractedData /= 255.0f;
    • By Devashish Khandelwal
      While writing a simple renderer using OpenGL, I faced an issue with the glGetUniformLocation function. For some reason, the location is coming to be -1.
      Anyone has any idea .. what should I do?
  • Advertisement