CODEWITHSUNDEEP
c++openglglslframebufferuniform
Raluca
Raluca

Reputation: 23

Texture units overlap? Rendered the wrong texture

I wanted to use 4 textures in my fragment shader. One is a cubemap, one is a rendered texture on a framebuffer and the last two are created from images.

When I try calling them in my fragment shader, I keep getting a different one than the one I called or the same one no matter which one I call (depending on different iterations I did when I was trying to fix it).

This is how I got it

GLuint FramebufferName = 0;
glGenFramebuffers(1, &FramebufferName);
glBindFramebuffer(GL_FRAMEBUFFER, FramebufferName);

GLuint renderedTexture;
glGenTextures(1, &renderedTexture);
glBindTexture(GL_TEXTURE_2D, renderedTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 1024, 1024, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, renderedTexture, 0);
GLenum DrawBuffers[1]={GL_COLOR_ATTACHMENT0};
glDrawBuffers(1, DrawBuffers);

if ( glCheckFramebufferStatus ( GL_FRAMEBUFFER ) == GL_FRAMEBUFFER_COMPLETE )
{
  glViewport(0, 0, 1024, 1024);
  glClearColor( 0.4f, 0.4f, 0.4f, 1.0f );
  glClear ( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

  ngl::ShaderLib* shader = ngl::ShaderLib::instance();
  (*shader)["Normal"]->use();
  m_transform.setPosition(0.0f, 0.0f, 0.0f);
  loadMatricesToShader();
  //drawing the quad
  prim->draw("tex");
}

glBindFramebuffer(GL_FRAMEBUFFER, 0);
glViewport(0,0,1024,768);

// grab an instance of the shader manager
ngl::ShaderLib* shader = ngl::ShaderLib::instance();
( *shader )[ "PBR" ]->use();

glUniform1i(renderedTexture, 1);

//initialize environment map
initEnvironment();

initTexture(2, m_glossMapTex, "images/gloss.png");
glUniform1i(m_glossMapTex, 2);
initTexture(3, m_textMap, "images/alege.png");
glUniform1i(m_textMap, 3);

Also the initTexture and initEnvironment

void NGLScene::initTexture(const GLuint& texUnit, GLuint &texId, const char *filename) {

glActiveTexture(GL_TEXTURE0 + texUnit);

// Load up the image using NGL routine
ngl::Image img(filename);

glGenTextures(1, &texId);

glBindTexture(GL_TEXTURE_2D, texId);

glTexImage2D (
            GL_TEXTURE_2D,    
            0,                
            img.format(),   
            img.width(),      
            img.height(),     
            0,                
            GL_RGB,          
            GL_UNSIGNED_BYTE, 
            img.getPixels()); 

// Set up parameters for our texture
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
}

void NGLScene::initEnvironment() {

glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
glActiveTexture (GL_TEXTURE0);
glGenTextures (1, &m_envTex);
glBindTexture(GL_TEXTURE_CUBE_MAP, m_envTex);

initEnvironmentSide(GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, "images/sky_zneg.png");
initEnvironmentSide(GL_TEXTURE_CUBE_MAP_POSITIVE_Z, "images/sky_zpos.png");
initEnvironmentSide(GL_TEXTURE_CUBE_MAP_POSITIVE_Y, "images/sky_ypos.png");
initEnvironmentSide(GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, "images/sky_yneg.png");
initEnvironmentSide(GL_TEXTURE_CUBE_MAP_NEGATIVE_X, "images/sky_xneg.png");
initEnvironmentSide(GL_TEXTURE_CUBE_MAP_POSITIVE_X, "images/sky_xpos.png");

glGenerateMipmap(GL_TEXTURE_CUBE_MAP);

glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_AUTO_GENERATE_MIPMAP, GL_TRUE);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
GLfloat anisotropy;
glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &anisotropy);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAX_ANISOTROPY_EXT, anisotropy);

// Set our cube map texture to on the shader so we can use it
ngl::ShaderLib *shader=ngl::ShaderLib::instance();
shader->use("PBR");
shader->setUniform("envMap", 0);
}

void NGLScene::initEnvironmentSide(GLenum target, const char *filename) {
// Load up the image using NGL routine
ngl::Image img(filename);

glTexImage2D (
  target,          
  0,                
  img.format(),     
  img.width(),     
  img.height(),    
  0,               
  GL_RGBA,         
  GL_UNSIGNED_BYTE, 
  img.getPixels()   
);
}

I feel like I have a gap in my knowledge of texture units and setting up uniforms, or maybe there is something wrong with my uniforms in my fragment shader.

Upvotes: 1

Views: 270

Answers (1)

Rabbid76
Rabbid76

Reputation: 210938

In your code there is a misunderstanding, how glUniform1i has to be used. If a values is assigned to a uniform, the the uniform has to be identified by the uniform location index. See Uniform (GLSL)

The fist parameter of glUniform1i has to be the location of the uniform and not the named texture object.

The location of a uniform can be set explicit, in shader by a Layout Qualifier

e.g.

GLSL

layout(location = 7) uniform sampler2D u_gloss;

C++

initTexture(2, m_glossMapTex, "images/gloss.png");
glUniform1i(7, 2); // uniform location 7

If the location of the uniform is not set by a layout qualifier, then the uniform location is set automatically when the program is linked. You can ask for this location by glGetUniformLocation:

e.g.

GLSL 

uniform sampler2D u_gloss;

C++

GLuint program_obj = ... ; // ( *shader )[ "PBR" ]->???
GLint gloss_location = glGetUniformLocation(program_obj , "u_gloss");

initTexture(2, m_glossMapTex, "images/gloss.png");
glUniform1i(gloss_location, 2);

Upvotes: 1

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