Thanks! you can email me at [email protected]

You can create the grid from 1x1 squares (patches) and scale them up by the world scale in the vertex shader, OR, you can scale them already in the vertex buffer and save up one multiplication. You usually use one heightmap for the entire grid and not just for a single patch. As you said, we sample the height in the evaluation shader so basically the grid is flat in the vertex buffer. I guess you can also scale it in the TES but I haven't tried that.

Glad you like them!

@@OGLDEV compare opengl with vulkan make me easier to understand ❤

OpenGL is great way to start

wow...

I agree and it's been on my todo list for quite some time. I'm not familiar with RenderDoc so I will try to find some time to learn it. I've been using apitrace which is very nice but probably less capable than RenderDoc.

@@OGLDEV RenderDoc saves me a lot of time, especially for stupid bug from my own mistakes 😅.

You're welcome!

:-)

kzbin.info/www/bejne/e6SogWyff7B1nrc

Thanks! maybe you can share more info on the problem. What do you mean it flips back and forth? Is it related to the uniforms? Perhaps it is just a matter of frame rate being too fast or the uniform value changes too drastically.

You're welcome! What do you mean by 'a 180 degrees lock'? Are you referring to gimbal? In general quaternions are the solution to a gimbal. Are you applying yaw and pitch correctly but as a side effect you're also getting a roll? Maybe you can share some code as an example.

If you specify the matrix in column major order you need to set transpose to GL_FALSE. Otherwise (row-major) use GL_TRUE.

@@OGLDEV GLM is column major, TIL. Thank you for the explanation.

Thanks, so everything is ok?

@@OGLDEV yup, everything is working well. Thanks again!

You're welcome :-)

Thank you! 🙂

You're very welcome!

Sure, here it is github.com/emeiri/ogldev/tree/master/TerrainWater

Thanks!

Glad to help!

My pleasure!

If you don't hit a performance wall with your specific game/app using OpenGL then I guess there is no real motivation to switch to Vulkan. Both Vulkan and DX12 originated from developers telling the HW vendors that they wanted more control over the GPU in order to extract every bit of performance from it.

@@OGLDEV Thanks for you time sir

Comparing Vulkan to OpenGL in terms of "how many lines of code I need to write to render triangle" doesn't make any sense. Sure Vulkan requires a lot of boilerplate to start but that doesn't mean doing everything else will require another hundreds lines of code. In fact when you have triangle with additional few hundreds lines of code you can render models loaded from file with textures and simple lighting.

Happy to hear that!

Thanks :-) Maybe I need to call this series 'Vulkan For OpenGL developers'...

Thanks for the feedback! I updated the code with your suggestion. Notice that I only did it in the newer Common/ogldev_basic_glfw_camera.cpp which is what I'm using right now and not in all the local copies of camera.cpp in the preceding tutorials before I switched to GLFW.

I added the missing 'noperspective' to all the vertex shaders where it was missing and replaced texture2D with texture. Please let me know if you still have problems with any of these tutorials. Thanks for the feedback!

@@OGLDEV Thank you for responding so quickly! But I still have problems when I try to run these tutorials after pull your update : "Invalid shader program: 'active samplers with a different type refer to the same texture image unit' Warning! Unable to get the location of uniform 'gWireframeColor' !!! Debug callback !!! Debug message: id 1, GL_INVALID_OPERATION in glDrawElements Message source: API Error type: Error Severity: High"

I pushed a fix to the 'active samplers...' error. Let's see if it improves something.

@@OGLDEV Everything works now! Thank you very much, I learned a lot with your tutorials.

Glad to hear!

Please check question #7 on ogldev.org/faq.html. Let me know if anything is missing.

@@OGLDEV Thank you. Will get back If I can't fix it.

You mean with the FreetypeGL library? I don't think you can generate vertices from fonts with that. AFAIK the standard font files are only 2D. If you need a 3D fonts then I guess you need a model for each letter and then render it as usual. I'm pretty sure that someone already modeled most languages and you can simply re-use this work.

​@@OGLDEV Yep, that one that you used. Thank you. I wasn't able to find similar lib yet. And I was surprised about that, pretty generic feature. Also on Khronos site I saw on page where they show libs for text rendering, that with some of libs they generate 3D text(I can't attach links here). Maybe this library encapsulates some functionality of FreeType for this task. I think the process of making 3D text from fonts should be next: 1) filter edges of letter. 2) make it vertices that forms plane of letter(and optimize it ammount). 3) duplicate this plane and flip to 3.14 rads and join both planes with perpendicular faces. 4) and then pack this all in vertex buffer and render as normal 3D model.

I would place the font image as a background picture in Blender and simply model it in 2D and then extend it backward to create the 3D volume. Can't tell which method is preferable. Highly depends on how much time you spend developing that algorithm.

​@@OGLDEV yep, I think you right. no sense to spend so much time on it if there is not so much need. I think I will be using this freetypeGL lib to put 2d text notes, to explain something in 3D scenes, projecting rectangle with this text texture. Yeah, much easier to make some kind of 3D askii table of letters and signs, and pick up needed one by interpreting chars, to render 3D text. Thank you)

Thanks! Not sure I understand the equation with texSize. Perhaps you can share more details. Regarding the second equestion - I usually create my slides using Google docs. Which specific blue slide are you referring to?

Sure, FreeGLUT supports all versions of OpenGL.

@@OGLDEV i need Glew o glad too or glut is enough?

You need either GLEW or GLAD to load the functions pointers. I'm using GLEW. People who follow learnopengl.com usually go with GLAD because this is what the website is using.

@@OGLDEV ok thank ,but i don't know how istall glad on codeblock it generata many version of opengl on website

Hopefully you can find an answer on learnopengl.com or on one of the forums. I've never tried to use GLAD myself. Was always happy using GLEW so I never tried an alternative.

You're welcome! Transitioning a set of vertices from being animated using one set of transformations to another is called blending because you need to smoothly switch from one matrix to another. If your model was constructed so that different parts have different sets of animations and you can freely mix and match between them then this is standard animation with the additional management complexity of allowing the user to specify the animation for each part. But as long as you don't need to do anything mathematically to get this to work you are still in standard animation land.

Better late than never - glad to have you on board :-)

This is what people keep telling me. I guess I need to make a video about it...

The question is definitely not silly it's just that I'm not sure I understood it. Are you implementing fog as a separate pass? Why do you need to change the clear color?

@@OGLDEV thanks for responding back. I ended up figuring out the issue sort of and working around it. I’m doing my fog in a separate pass and If the position was equal to 0 (which for some reason it is where no geometry is present), the shader was discarding in those places. I needed to get the fog color to cover those areas since some parts of the map if occluded were showing the clear color. I did a small branch and checked if the position is 0. If so I wrote the fog color and it fixed the empty parts of the map being black instead of being the color of the fog. Screen space reflections up next 😁

Great!

Have you tried using one of the online tools to convert code to pdf?

I'm using a very basic version of C++ so changing it to C should not be a problem.

Not sure I fully understood the first problem but this was with a software renderer. Is the problem still happening with OpenGL? The vertex behind the camera should end up being clipped and OpenGL should create a quad or whatever from what remains inside the frustum. It's possible that you don't really need to provide a solution with OpenGL. Regarding the projection equation: what is cameraDist and cameraZ? I guess the division by 't' corresponds to the perspective division that we have in OpenGL. If you look at the perspective projection matrix that we develop in the two videos you can see that most of it is zeroes which means that we usually just multiply each component of the vector by one element (except for Z which is a bit more complex). The advantage of the matrix vs your approach is that you can combine it with the world and view matrices into a single matrix.

@@OGLDEV because i need to have the projection calculation in the vertex shader to maximize performance, i can't control the number of vertices or create new triangles. The divisor 't' is the Z distance from the camera to the vertex, cameraZ is the Z coordiante of the camera, and cameraDist is the "FOV" of the camera, but in a weird way. Think of a pyramid representing the view frustum, the base would be the size of the window and the tip of the pyramid would be the origin of the camera, the height of the pyramid is cameraDist, so if i would want 90 degrees FOV, i would set cameraDist to be half the width of the window. So when a vertex that is behind the origin of the camera is projected, it now gets inverted due to t being negative, a similar thing happens if you write 1 / x in a graphing calculator, where x corresponds to t. The problem i tried to explain was that if i had a large triangle passing over the t = 0 plane, the resulting projection would be warped. The solution would be to either chop the triangle to a quad or to remove the triangle completely, Which is impossible to do inside the vertex shader. So how would that normally be fixed?

if you are wondering, here is my vertex shader: #version 330 core uniform float matrix[6]; uniform vec3 translate; uniform float renderdist; uniform float minrenderdist; uniform vec3 camera; uniform float cameradist; uniform vec2 size; uniform int prioaxis; // Input vertex attributes layout(location = 0) in vec3 position; // Position attribute layout(location = 1) in vec4 color; vec3 rotate(vec3 v) { float nx; float ny; vec3 o; if (prioaxis == 0) { // Y o = vec3(matrix[3] * v.x + matrix[2] * v.z, v.y, matrix[3] * v.z - matrix[2] * v.x); // Z nx = matrix[5] * o.x - matrix[4] * o.y; o.y = matrix[4] * o.x + matrix[5] * o.y; o.x = nx; // X ny = matrix[1] * o.y - matrix[0] * o.z; o.z = matrix[0] * o.y + matrix[1] * o.z; o.y = ny; } else if (prioaxis == 1) { // Z o = vec3(matrix[5] * v.x - matrix[4] * v.y, matrix[4] * v.x + matrix[5] * v.y, v.z); // X ny = matrix[1] * o.y - matrix[0] * o.z; o.z = matrix[0] * o.y + matrix[1] * o.z; o.y = ny; // Y nx = matrix[3] * o.x + matrix[2] * o.z; o.z = matrix[3] * o.z - matrix[2] * o.x; o.x = nx; } else { // X o = vec3(v.x, matrix[1] * v.y - matrix[0] * v.z, matrix[0] * v.y + matrix[1] * v.z); // Y nx = matrix[3] * o.x + matrix[2] * o.z; o.z = matrix[3] * o.z - matrix[2] * o.x; o.x = nx; // Z nx = matrix[5] * o.x - matrix[4] * o.y; o.y = matrix[4] * o.x + matrix[5] * o.y; o.x = nx; } return o; } vec2 project(vec3 v) { float t = cameradist - camera.z - v.z; if (t > minrenderdist) { float x1 = ((cameradist * v.x) / t) - camera.x; float y1 = ((cameradist * v.y) / t) - camera.y; return vec2(x1 / size.x, y1 / size.y); } else { return vec2(0.0, 0.0); } } out vec4 col; void main() { vec3 rotated = rotate(position + translate); vec2 projected = project(rotated); float t = cameradist - camera.z - rotated.z; gl_Position = vec4(projected, 1.0 - 1.0 / t, 1.0); col = color; }

Your method seems highly unorthodox. You should transform the vertex to view space and then the camera is at the origin so you don't need to subtract cameraZ from anything. In the vertex shader we usually combine all the transformations together into a single matrix (WVP) and then you don't need all the calculations in your shader below. The projection matrix provides a simple solution for the FOV so it doesn't have to be weird. Everything between the near and far clip plane will be mapped to (-1,1) and everything outside of that range should be handled correctly by the clipper. The vertex shader is indeed not the place to add or remove vertices. The clipper does that for you in screen space.

@@OGLDEV I re-implemented the perspective and rotation matrices to be the same as your implementation, but i keep getting stuck when the triangles just start flickering and popping in and out of existence when rotating, the translation matrix dossen't work as expected either. I have the same order of matrices "perspective * translation * rotation * vec4(position, 1.0);". what i also found was that if i force the w component to be 1.0, it stops flickering but i loose all sense of depth, what could be going on? theese are the matrices i am currently using: float d = 1.0f / (float) Math.tan(FOV / 2.0f); float[] perspective = new float[]{ d, 0.0f, 0.0f, 0.0f, 0.0f, d, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f }; float[] translation = new float[]{ 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f }; float[] rotation = new float[]{ cosA, 0.0f, -sinA, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, sinA, 0.0f, cosA, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f };

Thanks for the bug report. Turns out that I'm handing the special keys (arrows) in a function registered for the regular keys using glutKeyboardFunc. I should have registered a different callback using glutSpecialFunc and handle the arrows there. The code for 'D' is 0x64 which is used for GLUT_KEY_LEFT and this is causing the confusion.

I define _USE_MATH_DEFINES in the preprocessor config of every project which should solve this. For more details see learn.microsoft.com/en-us/cpp/c-runtime-library/math-constants?view=msvc-170 Perhaps you are building the 'release' build? I only maintain the 'debug' build.

You are most welcome!

You're welcome :-)

Wow! the video is more than two years old but because of your comment I now see that I used the wrong version of the Render function for the code review... The version in the video is for the instanced case (even though I haven't done a tutorial on instancing...) which is why glDrawElementsInstancedBaseVertex is used instead of the regular glDrawElementsBaseVertex. The file has changed a lot since then but you can simply take a look at the render function in 527 to see what I was supposed to review. The material stuff is basically the same in both versions so no problem. Thanks!

Shakespeare!

This function (and the entire class) is highly unoptimized. I consider it a reference in order to explain how animation works using Assimp. I'm sure the performance can be greatly improved. I would start by measuring and pinpointing the specific bottlenecks. This is usually the best strategy in order to avoid spending time on things that "feel" problematic but end up not affecting much of the performance. That being said, just from the top of my head I can see several functions that serially search for a matching node name which is a string comparison. You can replace the name with an index and then access the required slot directly. In addition, the algorithm handles the three transformations in the same way but you can skip a transformation if you know a-priori that it is not really part of the animation. For example, if you know that the scaling doesn't change you can ignore it entirely. These are just two quick ideas and I'm sure there are many others.

@@OGLDEV Thank you for the tips! Just using a simpler model drastically improved the performance as well.

Great!

Yes, it is. In a left handed coordinate system the positive direction is clockwise and in a right handed system it is counter clockwise. See more details here: butterflyofdream.wordpress.com/2016/07/05/converting-rotation-matrices-of-left-handed-coordinate-system/

You can use $(SolutionDir) or $(ProjectDir) as the base where the corresponding file exists (the solution file or the project file, respectively) and use a relative path from there. Whenever I run into such problems I often start with the absolute path (which is easier) and then change it into a relative path (which is more generic).

That's weird because GLfloat should be a typedef of float. What platform is this? Can you please print sizeof(GLfloat) and sizeof(float)?

@@OGLDEV Ignore this actually, just tried switching them back to regular float and it worked instantly. Might've been something else I did at the time that I didn't catch. Sorry about that !

No problem, glad to hear it is working.

The vertex may include zero or more (current maximum is 8) texture attributes. You need to call HasTextureCoords with the index of the coordinates and it will tell you whether it exists. I would have preferred an API that tells you how many tex coords exist but this is how it works. I'm only interested in the first set so I pass in zero. mTextureCoords is indeed one dimensional array but of pointers which means that every element in the array is the base of a different array. So the first index is zero for the first set of coords and the second index is 'I' for the coords of the current vertex.

@@OGLDEV Now I get it thank you. Just one more thing, do you still have the source code from the video? I looked at your github page but I couldn't find one.

The source code is here: github.com/emeiri/ogldev/tree/master/tutorial18_youtube. If you want to get the same version that was used in the video (the master branch contains many changes) checkout the tag TUT_18_ASSIMP.

@@OGLDEV Thank you. your videos are awesome.

Thanks!