• Advertisement
Sign in to follow this  

OpenGL Skybox cubemap not showing properly

This topic is 1990 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

I have used a cubemap to render my skybox, I am using openGL 3.3, GLSL 330.
The problem is that it's only showing a a blue skybox.
I can see inside gDEBugger that my cubemap is created properly.

Loading of my image files and creating the cubemap
[source lang="cpp"]void TextureCube::LoadTGA(std::string filename, bool mipmap)
{
// used vars
TGAFile tga[6];
memset(tga, 0, sizeof(TGAFile) * 6);
GLenum internForm;
GLenum externForm;

if(mTextureID != 0)
Dispose();

// fill in texture names
mTextures[0] = filename + "_lf.tga";
mTextures[1] = filename + "_rt.tga";
mTextures[2] = filename + "_bk.tga";
mTextures[3] = filename + "_ft.tga";
mTextures[4] = filename + "_dn.tga";
mTextures[5] = filename + "_up.tga";

// load each file
for(int i = 0; i < 6; i++)
{
if( !LoadImageTGA(mTextures, &tga))
{
printf("Could not load %s\n", mTextures.c_str());

// delete previous loaded tga
for(int j = 0; j < i;j++)
{
delete []tga.data;
}
return;
}
}

// set data
mWidth = tga[0].width;
mHeight = tga[0].height;

// create texture and bind it
glGenTextures(1, &mTextureID);
glBindTexture(GL_TEXTURE_CUBE_MAP, mTextureID);

// check which formats to use
if(tga[0].bytesperpixel == 1)
{
internForm = GL_LUMINANCE;
externForm = GL_LUMINANCE;
}
else if(tga[0].bytesperpixel == 3)
{
internForm = GL_RGB;
externForm = GL_BGR;
}
else if(tga[0].bytesperpixel == 4)
{
internForm = GL_RGBA;
externForm = GL_BGRA;
}

// set texture state
glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

// check if we want to generate mipmaps
if(mipmap)
{
glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
glGenerateMipmap(GL_TEXTURE_CUBE_MAP);
}
else
{
glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
}

// put the data inside
//glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X, 0, internForm, mWidth, mHeight, 0, externForm, GL_UNSIGNED_BYTE, tga[1].data);
glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_X, 0, internForm, mWidth, mHeight, 0, externForm, GL_UNSIGNED_BYTE, tga[0].data);
glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Y, 0, internForm, mWidth, mHeight, 0, externForm, GL_UNSIGNED_BYTE, tga[5].data);
glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, 0, internForm, mWidth, mHeight, 0, externForm, GL_UNSIGNED_BYTE, tga[4].data);
glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 0, internForm, mWidth, mHeight, 0, externForm, GL_UNSIGNED_BYTE, tga[3].data);
glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 0, internForm, mWidth, mHeight, 0, externForm, GL_UNSIGNED_BYTE, tga[2].data);


// unbind
glBindTexture(GL_TEXTURE_CUBE_MAP, 0);

//free memory
for(int i = 0; i < 6; i++)
{
delete []tga.data;
}
}[/source]

The rest:
[source lang="cpp"]class TextureCube
{
private:
std::string mTextures[6];
GLuint mTextureID;
GLuint mWidth;
GLuint mHeight;

public:
TextureCube() {}
~TextureCube() { Dispose(); }

// Create texture
GLvoid LoadTGA(std::string fileName, bool mipmap = false);

// methods
inline GLuint GetID() { return mTextureID; }
inline GLuint GetWidth() { return mWidth; }
inline GLuint GetHeight() { return mHeight; }
inline GLvoid Bind()
{
if(glIsTexture(mTextureID))
{
glBindTexture(GL_TEXTURE_CUBE_MAP, mTextureID);
}
else
{
printf("Not a valid texture name");
}
}

inline GLvoid Unbind() { glBindTexture(GL_TEXTURE_CUBE_MAP, 0); }

inline GLvoid Dispose()
{
if(mTextureID)
{
Unbind();
glDeleteTextures(1, &mTextureID);
}
}
};[/source]
Vertex shader:
[source lang="cpp"]#version 330

layout(location = 0) in vec3 inPos;
out vec3 outUV;
uniform mat4 mvpMatrix;

void main()
{
outUV = inPos;
gl_Position = mvpMatrix * vec4(inPos, 1.0);
}[/source]

Fragment shader:
[source lang="cpp"]#version 330

in vec3 UV;
out vec4 fragcolor;
uniform samplerCube cubeMap;

void main()
{
fragcolor = texture(cubeMap, UV);
}[/source]

Skybox class:
[source lang="cpp"]#ifndef SKYBOX_H_
#define SKYBOX_H_

#include <string>
#include "../System/CAbstractSystem.h"
#include "../Graphics/Buffers/VertexBuffer.h"
#include "../Graphics/TextureCube.h"
#include "../Graphics/Shader.h"
#include "Camera.h"

class Skybox
{
private:
// features
Camera* mCamera;
TextureCube mTexCube;
ShaderProgram mShader;

// buffers
VertexBuffer mVertices;
GLuint mElementsID;
GLuint vaoID;

public:
Skybox() {}

void Init(std::string fileName, Camera* camera)
{
mCamera = camera;

// vertex position in object space
GLfloat verticeAttrib[] =
{
// front
-1.0, -1.0, -1.0,
1.0, -1.0, -1.0,
1.0, 1.0, -1.0,
-1.0, 1.0, -1.0,
// top
-1.0, 1.0, -1.0,
1.0, 1.0, -1.0,
1.0, 1.0, 1.0,
-1.0, 1.0, 1.0,
// back
1.0, -1.0, 1.0,
-1.0, -1.0, 1.0,
-1.0, 1.0, 1.0,
1.0, 1.0, 1.0,
// bottom
-1.0, -1.0, 1.0,
1.0, -1.0, 1.0,
1.0, -1.0, -1.0,
-1.0, -1.0, -1.0,
// left
-1.0, -1.0, 1.0,
-1.0, -1.0, -1.0,
-1.0, 1.0, -1.0,
-1.0, 1.0, 1.0,
// right
1.0, -1.0, -1.0,
1.0, -1.0, 1.0,
1.0, 1.0, 1.0,
1.0, 1.0, -1.0,
};

GLushort elements[] = {
// front
0, 1, 2,
2, 3, 0,
// top
4, 5, 6,
6, 7, 4,
// back
8, 9, 10,
10, 11, 8,
// bottom
12, 13, 14,
14, 15, 12,
// left
16, 17, 18,
18, 19, 16,
// right
20, 21, 22,
22, 23, 20,
};

// generate vertex array object to melt all buffer objects
glGenVertexArrays(1,&vaoID);
glBindVertexArray(vaoID);

// create vertex buffer object
mVertices.Create(verticeAttrib, sizeof(verticeAttrib) / sizeof(GLfloat), GL_STATIC_DRAW);

// indices
glGenBuffers(1, &mElementsID);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mElementsID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elements), elements, GL_STATIC_DRAW);

// load texture
mTexCube.LoadTGA(fileName);

// shader data
std::string vertex;
std::string fragment;

// creating shaders
CAbstractSystem::LoadTextFile("Data\\shaders\\skybox.vert", vertex);
CAbstractSystem::LoadTextFile("Data\\shaders\\skybox.frag", fragment);

// load shaders
mShader.CreateProgram(vertex, fragment);
}

void Dispose()
{
mTexCube.Dispose();
mShader.Dispose();
mVertices.Dispose();

glDeleteBuffers(1, &mElementsID);

glBindVertexArray(0);
glDeleteVertexArrays(1, &vaoID);
}

~Skybox()
{
Dispose();
}

void Draw()
{
GLint OldCullFaceMode;
glGetIntegerv(GL_CULL_FACE_MODE, &OldCullFaceMode);
GLint OldDepthFuncMode;
glGetIntegerv(GL_DEPTH_FUNC, &OldDepthFuncMode);

glCullFace(GL_FRONT);
glDepthFunc(GL_LEQUAL);

Mat4 trans = Mat4::Translate(mCamera->GetWorld().GetPosition()) * Mat4::ScaleUniform(85);
Mat4 combined = mCamera->GetProjection() * mCamera->GetView() * trans;

//get matrix uniform
mShader.Bind();
int mLoc = glGetUniformLocation(mShader.GetID(), "mvpMatrix");
glUniformMatrix4fv(mLoc, 1, GL_FALSE, (GLfloat*)&combined);

//enable vertex position
mVertices.Bind();
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(0);

mTexCube.Bind();
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mElementsID);
glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_SHORT, 0);

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
glDisableVertexAttribArray(0); // vertex positions

glCullFace(OldCullFaceMode);
glDepthFunc(OldDepthFuncMode);

mVertices.Unbind();
mTexCube.Unbind();
mShader.Unbind();
}
};

#endif[/source] Edited by Wilds

Share this post


Link to post
Share on other sites
Advertisement
I would say the problem is in your mvpMatrix. From your code, it seems you add translation, which shouldn't be there. Edited by Ignifex

Share this post


Link to post
Share on other sites
The cube coordinates are not affected by the transformation as the shader gets the untransformed object space vertices from the VBO.

Share this post


Link to post
Share on other sites
I have no other good ideas other than make each side a different color. And see if at least the left is all red, right is all blue. If so, it could be doing something completely wrong. I would post a pic. Are you drawing any of the scene with it? Is your glClearColor blue? Maybe you aren't pointing the normals inward and its not drawing the skybox at all just using the clear color?

Share this post


Link to post
Share on other sites
hi, the proper way to do skyboxes is the following:
obviously create a 1x1x1 box in blender or whatever editor you prefer. you can just export the default cube to the obj format. (make sure you set normals to smooth!)
Load the 6 faces of your cubemap into a cubemap texture, and when you render it bind it to the GL_TEXTURE_CUBE_MAP target.
When rendering the skybox make sure you disable depth testing. this way you can make sure that the skybox is rendered properly behind everything.
then you have to pass a matrix to your shader: the inverse of your modelview matrix.
then use these shaders:

[vertex shader]
//set version to your target version
#version 420 core

uniform mat4 modelview_inv; //here comes the inverse modelview matrix

in vec4 in_vertex; //here comes the vertex data (ie. the cube)

out cross_shader_data
{
vec3 tex_coord; //this gets passed to the pixel shader to sample the cubemap
} o;

void main()
{
o.tex_coord = mat3(modelview_inv) * in_vertex.xyz; //calculate the texture coordinate, then interpolate along the cube faces
gl_Position = in_vertex; //here's a trick: since we don't transform the cube it will always stay at (0, 0, 0) therefore wherever you go, it stays with you
}

[pixel shader]
//again set the version
#version 420 core

uniform samplerCube texture0; //you need to use a samplerCube for cubemapping

in cross_shader_data
{
vec3 tex_coord; //incoming texture coordinates
} i;

out vec4 color; //this gets drawn into the framebuffer

void main()
{
color = texture(texture0, i.tex_coord); //sample the cubemap along the coordinates
}


it is important to note that you either need to draw the cubemap before rendering anything (so that it doesn't cover any other objects), or you can use stenciling for optimizing the whole thing, and this way you'll need to draw the skybox last.
to add you'll probably need to adjust (rotate) the incoming cubemap faces (textures), because they may be in other coordinate system, and therefore they may not be in their place when rendered. Edited by Yours3!f

Share this post


Link to post
Share on other sites
For your method: you aren't using a skybox, you are using a backdrop. Because of the fact you never rotate the box. That is the only reason you need to pass the modelview inverse and what not.

Secondly: Why use a stencil map in your method? Since you are using only 1 face of the cubemap (a backdrop plane). Why don't u just translate it to the end of the farplane and get rid of stencil operations completely and just use depth testing?

I wouldn't say that is the proper way. You are doing extra work to generate the same texture coordinates as this guy is with a static cube that gets rotated. And needing to pass extra data and perform extra operations with the inverse. Typically that method is more for a cube mapped object in the world.

here's a trick: since we don't transform the cube it will always stay at (0, 0, 0) therefore wherever you go, it stays with you[/quote]
All you need to do to get that trick without using the inverse is just don't pass the translation portion of the camera matrix and just the rotation.

Share this post


Link to post
Share on other sites
Nope.

Draw as a 10x10x10 cube centered on the camera origin (I'm using 10 here because it's going to be comfortably above your near clipping plane distance; adjust as required) but otherwise untransformed. Draw it last, after everything else. Use glDepthRange (1, 1). Disable depth writing but leave depth test enabled.

This way you get correct positioning, early-Z, skybox behind all objects and minimal fillrate overhead.

Share this post


Link to post
Share on other sites
Is anyone looking at my code? I am already doing the thing mhagain is doing (sorta). Edited by Wilds

Share this post


Link to post
Share on other sites

For your method: you aren't using a skybox, you are using a backdrop. Because of the fact you never rotate the box. That is the only reason you need to pass the modelview inverse and what not.

Secondly: Why use a stencil map in your method? Since you are using only 1 face of the cubemap (a backdrop plane). Why don't u just translate it to the end of the farplane and get rid of stencil operations completely and just use depth testing?

I wouldn't say that is the proper way. You are doing extra work to generate the same texture coordinates as this guy is with a static cube that gets rotated. And needing to pass extra data and perform extra operations with the inverse. Typically that method is more for a cube mapped object in the world.

here's a trick: since we don't transform the cube it will always stay at (0, 0, 0) therefore wherever you go, it stays with you

All you need to do to get that trick without using the inverse is just don't pass the translation portion of the camera matrix and just the rotation.
[/quote]
well you'd do stenciling anyways for lighting, so it may come handy. you'd use more than one face of the cube, because of perspectivity, but it's true that if you render it to the back of your frustum than it's the same. I don't think that's extra work. it's 1 matrix mul vs 1 matrix mul... (plus only 1 matrix gets passed, vs 1 matrix passed, that is the same amount of data passed :) )

Share this post


Link to post
Share on other sites
what i can conclude is that it only picks the front texture, the +Z, I concluded this by making each part of the cubemap a different color.

I have added a link to my executable! please tell me the results.
Windows only: download Edited by Wilds

Share this post


Link to post
Share on other sites

The cube coordinates are not affected by the transformation as the shader gets the untransformed object space vertices from the VBO.


gl_Position shouldn't be translated either to keep the cube centered on the camera. Try Ignifex' suggestion and use Mat4 combined = mCamera->GetProjection() * mCamera->GetView(); without the translation part.

Share this post


Link to post
Share on other sites
I translate the cube's position to the camera's to keep it's position at the center of the camera.
I tried what you suggested, the translation of the position shouldn't affect texture coords, only which textures I am seeing based on the cube's orientation.

Share this post


Link to post
Share on other sites
Ah, that clears up your idea behind the code there and your method should work.
Honestly though, there are only a few things that can still go wrong:
- mCamera->getView() does not handle rotation, although I am sure you use it in other parts of your code as well.
- The translation you apply to move the cube toward the camera is wrong. Why the scale 85?
For the above two, the obvious thing to try is to render your texture coordinates as RGB and see what you get.
Although unlikely:
- Your binding of the cube map faces is still wrong. Could you set your uniform samplerCube cubeMap to 0, just to be safe?

Share this post


Link to post
Share on other sites
Thanks for your comment I tried visually debugging the skybox, it seems the texture coordinate passed is 0,0,0 the faces are all black!

- mCamera->getView() does not handle rotation, although I am sure you use it in other parts of your code as well.
It handles rotation as it is the inverse of the camera's world matrice.

- The translation you apply to move the cube toward the camera is wrong. Why the scale 85?
This one is also correct, the 85 scale is just a test value.

For the above two, the obvious thing to try is to render your texture coordinates as RGB and see what you get.
Although unlikely:
- Your binding of the cube map faces is still wrong. Could you set your uniform samplerCube cubeMap to 0, just to be safe?
Could you tell me how I do this, as just putting 0 behind uniform samplerCube tex is not working.

Share this post


Link to post
Share on other sites
Oke I solved it! thanks everyone, especially Ignifex, your tip about visually debugging helped me alot!
Good learning lesson, always name the input of the fragment shader the same as the output of the vertex shader!

The problem:
In the shaders i named the linking output and input of the vertex to fragment shaders differently.

Wrong
out vec3 outUV; // inside vertex shader
in vec3 UV; // inside fragment shader

Good:
out vec3 UV; // inside vertex shader
in Vec3 UV; // inside fragment shader Edited by Wilds

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 reenigne
      For those that don't know me. I am the individual who's two videos are listed here under setup for https://wiki.libsdl.org/Tutorials
      I also run grhmedia.com where I host the projects and code for the tutorials I have online.
      Recently, I received a notice from youtube they will be implementing their new policy in protecting video content as of which I won't be monetized till I meat there required number of viewers and views each month.

      Frankly, I'm pretty sick of youtube. I put up a video and someone else learns from it and puts up another video and because of the way youtube does their placement they end up with more views.
      Even guys that clearly post false information such as one individual who said GLEW 2.0 was broken because he didn't know how to compile it. He in short didn't know how to modify the script he used because he didn't understand make files and how the requirements of the compiler and library changes needed some different flags.

      At the end of the month when they implement this I will take down the content and host on my own server purely and it will be a paid system and or patreon. 

      I get my videos may be a bit dry, I generally figure people are there to learn how to do something and I rather not waste their time. 
      I used to also help people for free even those coming from the other videos. That won't be the case any more. I used to just take anyone emails and work with them my email is posted on the site.

      I don't expect to get the required number of subscribers in that time or increased views. Even if I did well it wouldn't take care of each reoccurring month.
      I figure this is simpler and I don't plan on putting some sort of exorbitant fee for a monthly subscription or the like.
      I was thinking on the lines of a few dollars 1,2, and 3 and the larger subscription gets you assistance with the content in the tutorials if needed that month.
      Maybe another fee if it is related but not directly in the content. 
      The fees would serve to cut down on the number of people who ask for help and maybe encourage some of the people to actually pay attention to what is said rather than do their own thing. That actually turns out to be 90% of the issues. I spent 6 hours helping one individual last week I must have asked him 20 times did you do exactly like I said in the video even pointed directly to the section. When he finally sent me a copy of the what he entered I knew then and there he had not. I circled it and I pointed out that wasn't what I said to do in the video. I didn't tell him what was wrong and how I knew that way he would go back and actually follow what it said to do. He then reported it worked. Yea, no kidding following directions works. But hey isn't alone and well its part of the learning process.

      So the point of this isn't to be a gripe session. I'm just looking for a bit of feed back. Do you think the fees are unreasonable?
      Should I keep the youtube channel and do just the fees with patreon or do you think locking the content to my site and require a subscription is an idea.

      I'm just looking at the fact it is unrealistic to think youtube/google will actually get stuff right or that youtube viewers will actually bother to start looking for more accurate videos. 
    • By Balma Alparisi
      i got error 1282 in my code.
      sf::ContextSettings settings; settings.majorVersion = 4; settings.minorVersion = 5; settings.attributeFlags = settings.Core; sf::Window window; window.create(sf::VideoMode(1600, 900), "Texture Unit Rectangle", sf::Style::Close, settings); window.setActive(true); window.setVerticalSyncEnabled(true); glewInit(); GLuint shaderProgram = createShaderProgram("FX/Rectangle.vss", "FX/Rectangle.fss"); float vertex[] = { -0.5f,0.5f,0.0f, 0.0f,0.0f, -0.5f,-0.5f,0.0f, 0.0f,1.0f, 0.5f,0.5f,0.0f, 1.0f,0.0f, 0.5,-0.5f,0.0f, 1.0f,1.0f, }; GLuint indices[] = { 0,1,2, 1,2,3, }; GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); GLuint vbo; glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(vertex), vertex, GL_STATIC_DRAW); GLuint ebo; glGenBuffers(1, &ebo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices,GL_STATIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, false, sizeof(float) * 5, (void*)0); glEnableVertexAttribArray(0); glVertexAttribPointer(1, 2, GL_FLOAT, false, sizeof(float) * 5, (void*)(sizeof(float) * 3)); glEnableVertexAttribArray(1); GLuint texture[2]; glGenTextures(2, texture); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageOne = new sf::Image; bool isImageOneLoaded = imageOne->loadFromFile("Texture/container.jpg"); if (isImageOneLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageOne->getSize().x, imageOne->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageOne->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageOne; glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageTwo = new sf::Image; bool isImageTwoLoaded = imageTwo->loadFromFile("Texture/awesomeface.png"); if (isImageTwoLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageTwo->getSize().x, imageTwo->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageTwo->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageTwo; glUniform1i(glGetUniformLocation(shaderProgram, "inTextureOne"), 0); glUniform1i(glGetUniformLocation(shaderProgram, "inTextureTwo"), 1); GLenum error = glGetError(); std::cout << error << std::endl; sf::Event event; bool isRunning = true; while (isRunning) { while (window.pollEvent(event)) { if (event.type == event.Closed) { isRunning = false; } } glClear(GL_COLOR_BUFFER_BIT); if (isImageOneLoaded && isImageTwoLoaded) { glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glUseProgram(shaderProgram); } glBindVertexArray(vao); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr); glBindVertexArray(0); window.display(); } glDeleteVertexArrays(1, &vao); glDeleteBuffers(1, &vbo); glDeleteBuffers(1, &ebo); glDeleteProgram(shaderProgram); glDeleteTextures(2,texture); return 0; } and this is the vertex shader
      #version 450 core layout(location=0) in vec3 inPos; layout(location=1) in vec2 inTexCoord; out vec2 TexCoord; void main() { gl_Position=vec4(inPos,1.0); TexCoord=inTexCoord; } and the fragment shader
      #version 450 core in vec2 TexCoord; uniform sampler2D inTextureOne; uniform sampler2D inTextureTwo; out vec4 FragmentColor; void main() { FragmentColor=mix(texture(inTextureOne,TexCoord),texture(inTextureTwo,TexCoord),0.2); } I was expecting awesomeface.png on top of container.jpg

    • By khawk
      We've just released all of the source code for the NeHe OpenGL lessons on our Github page at https://github.com/gamedev-net/nehe-opengl. code - 43 total platforms, configurations, and languages are included.
      Now operated by GameDev.net, NeHe is located at http://nehe.gamedev.net where it has been a valuable resource for developers wanting to learn OpenGL and graphics programming.

      View full story
    • By TheChubu
      The Khronos™ Group, an open consortium of leading hardware and software companies, announces from the SIGGRAPH 2017 Conference the immediate public availability of the OpenGL® 4.6 specification. OpenGL 4.6 integrates the functionality of numerous ARB and EXT extensions created by Khronos members AMD, Intel, and NVIDIA into core, including the capability to ingest SPIR-V™ shaders.
      SPIR-V is a Khronos-defined standard intermediate language for parallel compute and graphics, which enables content creators to simplify their shader authoring and management pipelines while providing significant source shading language flexibility. OpenGL 4.6 adds support for ingesting SPIR-V shaders to the core specification, guaranteeing that SPIR-V shaders will be widely supported by OpenGL implementations.
      OpenGL 4.6 adds the functionality of these ARB extensions to OpenGL’s core specification:
      GL_ARB_gl_spirv and GL_ARB_spirv_extensions to standardize SPIR-V support for OpenGL GL_ARB_indirect_parameters and GL_ARB_shader_draw_parameters for reducing the CPU overhead associated with rendering batches of geometry GL_ARB_pipeline_statistics_query and GL_ARB_transform_feedback_overflow_querystandardize OpenGL support for features available in Direct3D GL_ARB_texture_filter_anisotropic (based on GL_EXT_texture_filter_anisotropic) brings previously IP encumbered functionality into OpenGL to improve the visual quality of textured scenes GL_ARB_polygon_offset_clamp (based on GL_EXT_polygon_offset_clamp) suppresses a common visual artifact known as a “light leak” associated with rendering shadows GL_ARB_shader_atomic_counter_ops and GL_ARB_shader_group_vote add shader intrinsics supported by all desktop vendors to improve functionality and performance GL_KHR_no_error reduces driver overhead by allowing the application to indicate that it expects error-free operation so errors need not be generated In addition to the above features being added to OpenGL 4.6, the following are being released as extensions:
      GL_KHR_parallel_shader_compile allows applications to launch multiple shader compile threads to improve shader compile throughput WGL_ARB_create_context_no_error and GXL_ARB_create_context_no_error allow no error contexts to be created with WGL or GLX that support the GL_KHR_no_error extension “I’m proud to announce OpenGL 4.6 as the most feature-rich version of OpenGL yet. We've brought together the most popular, widely-supported extensions into a new core specification to give OpenGL developers and end users an improved baseline feature set. This includes resolving previous intellectual property roadblocks to bringing anisotropic texture filtering and polygon offset clamping into the core specification to enable widespread implementation and usage,” said Piers Daniell, chair of the OpenGL Working Group at Khronos. “The OpenGL working group will continue to respond to market needs and work with GPU vendors to ensure OpenGL remains a viable and evolving graphics API for all its customers and users across many vital industries.“
      The OpenGL 4.6 specification can be found at https://khronos.org/registry/OpenGL/index_gl.php. The GLSL to SPIR-V compiler glslang has been updated with GLSL 4.60 support, and can be found at https://github.com/KhronosGroup/glslang.
      Sophisticated graphics applications will also benefit from a set of newly released extensions for both OpenGL and OpenGL ES to enable interoperability with Vulkan and Direct3D. These extensions are named:
      GL_EXT_memory_object GL_EXT_memory_object_fd GL_EXT_memory_object_win32 GL_EXT_semaphore GL_EXT_semaphore_fd GL_EXT_semaphore_win32 GL_EXT_win32_keyed_mutex They can be found at: https://khronos.org/registry/OpenGL/index_gl.php
      Industry Support for OpenGL 4.6
      “With OpenGL 4.6 our customers have an improved set of core features available on our full range of OpenGL 4.x capable GPUs. These features provide improved rendering quality, performance and functionality. As the graphics industry’s most popular API, we fully support OpenGL and will continue to work closely with the Khronos Group on the development of new OpenGL specifications and extensions for our customers. NVIDIA has released beta OpenGL 4.6 drivers today at https://developer.nvidia.com/opengl-driver so developers can use these new features right away,” said Bob Pette, vice president, Professional Graphics at NVIDIA.
      "OpenGL 4.6 will be the first OpenGL release where conformant open source implementations based on the Mesa project will be deliverable in a reasonable timeframe after release. The open sourcing of the OpenGL conformance test suite and ongoing work between Khronos and X.org will also allow for non-vendor led open source implementations to achieve conformance in the near future," said David Airlie, senior principal engineer at Red Hat, and developer on Mesa/X.org projects.

      View full story
    • By _OskaR
      Hi,
      I have an OpenGL application but without possibility to wite own shaders.
      I need to perform small VS modification - is possible to do it in an alternative way? Do we have apps or driver modifictions which will catch the shader sent to GPU and override it?
  • Advertisement