Jump to content
  • Advertisement
Sign in to follow this  
juanmanuelsanchez

OpenGL Lighting questions

This topic is 4137 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 all ! well my plan is to make a soccer simulator, this means I will need lots of lights (stadiums). So my question is. Wich is the best method or aproach for this? I cant use OpenGl lighting because is a resource eater, plus they are limited. So any recomendation is welcome. Also Making some test I coded a spotlight, now the weird thing is that if I set the cutoff angle to something less that 90º I get somekind of weird split on the screen (half of it has light the other half is shadowed) and its always facing the camera... This is the code that activates the light)

Lights.SetPosition(-2022.3320f,	-1185.0239f,	1263.6978f,1.0);
	Lights.SetSpotDirection(82.0830f,	-17.6392f,	0.0000f);
	Lights.SetAmbientColor(0.8980f,	0.1373f,	0.1373f,  0.0f);
//	Lights.SetSpotCutoff(43.0000f);
    Lights.TurnOn(GL_LIGHT1);

void CGL_Light3D::TurnOn ( int light ) {

    
	LIGHT=light;


	glEnable(LIGHT);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity(); // comenta esto para ver las bolitas

	glLightfv(LIGHT, GL_POSITION, position);
	glLightfv(LIGHT, GL_AMBIENT, ambient);
    glLightfv(LIGHT, GL_DIFFUSE, ambient);
    glLightfv(LIGHT, GL_SPECULAR, ambient);
	glLightf(LIGHT, GL_SPOT_EXPONENT,spot_exponent);
	glLightfv(LIGHT, GL_SPOT_DIRECTION, spot_direction);
//	glLightf(LIGHT, GL_SPOT_CUTOFF,spot_cutoff);
	glLightf(LIGHT, GL_CONSTANT_ATTENUATION, constant_attenuation);
	glLightf(LIGHT, GL_LINEAR_ATTENUATION, linear_attenuation);
	glLightf(LIGHT, GL_QUADRATIC_ATTENUATION, quadratic_attenuation);

    //glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,1);

}

Share this post


Link to post
Share on other sites
Advertisement
1.:

Why would you need that many lights for a soccer simulator? From my experience, a stadium only has a few huge spot lights, lets say 4, one at or near each corner. Those huge spots are actually a collection of smaller spots, but can be approximated by a single light, since all small spots have roughly the same position (they are at quite a distance from the players or won't be visible at all).

You could use a directional light to light the soccer field/players etc. This would be a quick approximation that shouldn't be that obvious (for the reasons I explained above). You also could light the stadium with those directional lights or use some other lighting method if it isn't sufficient.

For the players you then could employ a shadowmap for each of the 4 directional lights to get those 4 typical shadows.


2.:
Your "weird" spot light: could you show us a screenshot of what's happening?
Do you apply any camera tranform before rendering?
Why don't you use some simpler values for position, direction, color etc. so that you could check the results more easily?

Share this post


Link to post
Share on other sites
Here is the pic, if I move the camera, the shadow also moves (the thing is that I dont have shadow maps)

http://img213.imageshack.us/img213/2412/lightbt9.jpg

Also yes Im making some camera tranformations, ie moving the camera.
Here is the rendering code, Im also rendering some spheres for reference to see where the light is and where is pointing


void CGL_Light3D::Render(glCamera *Cam)
{

GLfloat white[] = { 1.0, 1.0, 1.0, 1.0 };

//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);


gluLookAt(Cam->m_Position.x, Cam->m_Position.y, Cam->m_Position.z,0.0,0.0,0.0, 0.0, 1.0, 0.0);

glPushMatrix();
glDisable(GL_LIGHTING);
// glRotatef(m_lightAngle, 1.0, 0.0, 0.0);
// glRotatef(m_lightAngle, 0.0, 1.0, 0.0);
glTranslatef(position[0], position[1], position[2]);
glColor3fv(ambient);
gluSphere(m_pSphere, 100.0f, 10, 10);
glEnable(GL_LIGHTING);
glPopMatrix();

glPushMatrix();
glDisable(GL_LIGHTING);
// glRotatef(m_lightAngle, 1.0, 0.0, 0.0);
// glRotatef(m_lightAngle, 0.0, 1.0, 0.0);
glTranslatef(spot_direction[0],spot_direction[1], spot_direction[2]);
glColor3fv(white);
gluSphere(m_pSphere, 100.0f, 10, 10);
glEnable(GL_LIGHTING);
glPopMatrix();


}



Share this post


Link to post
Share on other sites
The light comes from the right of the picture, right? Doesn't seem that bad to me. What do you expect, the model fully lit?

Remember that the direction the spot is pointing to is a *direction* not a position. You should render the second sphere (light "target") at pos = light.position + light.direction.

When do you render your model? Before or after the light's spheres?

Try to mode that gluLookAt to another place, e.g. to the beginning of your top level render function. Also remove that glLoadIdentity() from your light enabling code, since this will result in the light beeing at the same position but the model is moved by the inverse camera movement (remember that OpenGL treats the moving camera as moving the world by the inverse, calling glLoadIdentity() undos that movement, so the light stays at the same relative position to the light).

If you specifiy cutoff = 90 you'll end up with a 180 degree spotlight which would affect you whole model if the light points towards it. Setting cutoff to something between 0 and 90 will result in a smaller spot that may affect only parts of your model. And if you have default attenuation setting (which is constant=1, linear=0, quadratic=0 => "no attenutation") there will be that "sharp" transition from lit to unlit parts of your model.

Share this post


Link to post
Share on other sites
well from the pic it looks correct, the problem becomes when I move the camera, then light effect moves and the shadow does the same too, its like having a moving flashlight cutted in half.

here you can see what I mean (I just moved the camera)

http://img181.imageshack.us/img181/1062/lightjk4.jpg

And yes I render the model before the lights

Share this post


Link to post
Share on other sites
Remove that glIdentity() call before setting up the light. The light position has to be given in world space. You set the light in camera space. This is because the world is effectively transformed by the inverse camera matrix, but that glIdentity() undos that transformation and thus your light stays in camera space and moves with the camera.

Do something like this (pseudocode):

start render function
set camera
set light(s) (without glIdentity())
for each model
save modelview matrix
transform model (translate, rotate etc.)
render model
restore modelview matrix (will restore to camera transformation)
render your light spheres (note to use position + direction for the "target" sphere)
end render function

Share this post


Link to post
Share on other sites
thats how Im doing it atm,except for the identity error.
I think my problem is that Im using a Quaternion based camera.

This is what I do with the camera.



glCamera::glCamera()
{
outs("glCamera::glCamera()",0);
// Initalize all our member varibles.
m_MaxPitchRate = 0.0f;
m_MaxHeadingRate = 0.0f;
m_HeadingDegrees = 0.0f;
m_PitchDegrees = 0.0f;
m_MaxForwardVelocity = 0.0f;
m_ForwardVelocity = 0.0f;
}

void glCamera::SetPrespective()
{
GLfloat Matrix[16];
glQuaternion q;

// Make the Quaternions that will represent our rotations
m_qPitch.CreateFromAxisAngle(1.0f, 0.0f, 0.0f, m_PitchDegrees);
m_qHeading.CreateFromAxisAngle(0.0f, 1.0f, 0.0f, m_HeadingDegrees);

// Combine the pitch and heading rotations and store the results in q
q = m_qPitch * m_qHeading;
q.CreateMatrix(Matrix);

// Let OpenGL set our new prespective on the world!
glMultMatrixf(Matrix);

// Create a matrix from the pitch Quaternion and get the j vector
// for our direction.
m_qPitch.CreateMatrix(Matrix);
m_DirectionVector.j = Matrix[9];

// Combine the heading and pitch rotations and make a matrix to get
// the i and j vectors for our direction.
q = m_qHeading * m_qPitch;
q.CreateMatrix(Matrix);
m_DirectionVector.i = Matrix[8];
m_DirectionVector.k = Matrix[10];

// Scale the direction by our speed.
m_DirectionVector *= m_ForwardVelocity;

// Increment our position by the vector
m_Position.x += m_DirectionVector.i;
m_Position.y += m_DirectionVector.j;
m_Position.z += m_DirectionVector.k;

// Translate to our new position.
glTranslatef(-m_Position.x, -m_Position.y, m_Position.z);
}

void glCamera::ChangePitch(GLfloat degrees)
{
if(fabs(degrees) < fabs(m_MaxPitchRate))
{
// Our pitch is less than the max pitch rate that we
// defined so lets increment it.
m_PitchDegrees += degrees;
}
else
{
// Our pitch is greater than the max pitch rate that
// we defined so we can only increment our pitch by the
// maximum allowed value.
if(degrees < 0)
{
// We are pitching down so decrement
m_PitchDegrees -= m_MaxPitchRate;
}
else
{
// We are pitching up so increment
m_PitchDegrees += m_MaxPitchRate;
}
}

// We don't want our pitch to run away from us. Although it
// really doesn't matter I prefer to have my pitch degrees
// within the range of -360.0f to 360.0f
if(m_PitchDegrees > 360.0f)
{
m_PitchDegrees -= 360.0f;
}
else if(m_PitchDegrees < -360.0f)
{
m_PitchDegrees += 360.0f;
}
}




And this is where I set the rotaion for the mouse and the render


void CheckMouse(void)
{

GLfloat DeltaMouse;
POINT pt;

GetCursorPos(&pt);

MouseX = pt.x;
MouseY = pt.y;



if(MouseX < CenterX)
{

DeltaMouse = GLfloat(CenterX - MouseX);

Cam->ChangeHeading(-0.2f * DeltaMouse);

}
else if(MouseX > CenterX)
{
DeltaMouse = GLfloat(MouseX - CenterX);

Cam->ChangeHeading(0.2f * DeltaMouse);
}

if(MouseY < CenterY)
{
DeltaMouse = GLfloat(CenterY - MouseY);

Cam->ChangePitch(-0.2f * DeltaMouse);
}
else if(MouseY > CenterY)
{
DeltaMouse = GLfloat(MouseY - CenterY);

Cam->ChangePitch(0.2f * DeltaMouse);
}

MouseX = CenterX;
MouseY = CenterY;

SetCursorPos(CenterX, CenterY);
}

void CameraMovement(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glLoadIdentity();
Cam->SetPrespective();
CheckMouse();
}

Share this post


Link to post
Share on other sites
Just to clarify:

Perspective means "How is the 3D content that is visible to the camera projected into 2D space?", i.e. it should not have anything to do with your camera direction. You did use the MODELVIEW matrix mode, didn't you?

Also, why do you check the mouse AFTER setting the camera?

I don't see an error in your SetPerspective() method (except for the name). Unless your Quaternion code is correct it should work.

Share this post


Link to post
Share on other sites
well the camera works, there is no problem with that. Btw I use the checkmouse because I lock the mouse at the center of the app so when I move I change the camera view, ie mouse hoes left cam goes left.

But I cant find why the light acts weird when I move the camera.

When you told me to use cam position + cam direction, you mean do something like this?

glTranslatef(spot_direction[0]+position[0],spot_direction[1]+position[1], spot_direction[2]+position[2]);

If thats the case, it dosent work, both balls are almost one next to the other, when one (ambient) should be the source of the light and the white one the spot where the light is pointing...

Atm Im just rendering the light and the model, this is how I render the model

void ASE::render()
{
if (! loaded)
return;
glPushMatrix();
glScalef(currentScale, currentScale, currentScale);
glCallList(dlist);
glPopMatrix();
}


Share this post


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

  • Advertisement
  • Advertisement
  • Popular Tags

  • Similar Content

    • By nOoNEE
      i am reading this book : link
      in the OpenGL Rendering Pipeline section there is a picture like this: link
      but the question is this i dont really understand why it is necessary to turn pixel data in to fragment and then fragment into pixel could please give me a source or a clear Explanation that why it is necessary ? thank you so mu
       
       
    • By Inbar_xz
      I'm using the OPENGL with eclipse+JOGL.
      My goal is to create movement of the camera and the player.
      I create main class, which create some box in 3D and hold 
      an object of PlayerAxis.
      I create PlayerAxis class which hold the axis of the player.
      If we want to move the camera, then in the main class I call to 
      the func "cameraMove"(from PlayerAxis) and it update the player axis.
      That's work good.
      The problem start if I move the camera on 2 axis, 
      for example if I move with the camera right(that's on the y axis)
      and then down(on the x axis) -
      in some point the move front is not to the front anymore..
      In order to move to the front, I do
      player.playerMoving(0, 0, 1);
      And I learn that in order to keep the front move, 
      I need to convert (0, 0, 1) to the player axis, and then add this.
      I think I dont do the convert right.. 
      I will be glad for help!

      Here is part of my PlayerAxis class:
       
      //player coordinate float x[] = new float[3]; float y[] = new float[3]; float z[] = new float[3]; public PlayerAxis(float move_step, float angle_move) { x[0] = 1; y[1] = 1; z[2] = -1; step = move_step; angle = angle_move; setTransMatrix(); } public void cameraMoving(float angle_step, String axis) { float[] new_x = x; float[] new_y = y; float[] new_z = z; float alfa = angle_step * angle; switch(axis) { case "x": new_z = addVectors(multScalar(z, COS(alfa)), multScalar(y, SIN(alfa))); new_y = subVectors(multScalar(y, COS(alfa)), multScalar(z, SIN(alfa))); break; case "y": new_x = addVectors(multScalar(x, COS(alfa)), multScalar(z, SIN(alfa))); new_z = subVectors(multScalar(z, COS(alfa)), multScalar(x, SIN(alfa))); break; case "z": new_x = addVectors(multScalar(x, COS(alfa)), multScalar(y, SIN(alfa))); new_y = subVectors(multScalar(y, COS(alfa)), multScalar(x, SIN(alfa))); } x = new_x; y = new_y; z = new_z; normalization(); } public void playerMoving(float x_move, float y_move, float z_move) { float[] move = new float[3]; move[0] = x_move; move[1] = y_move; move[2] = z_move; setTransMatrix(); float[] trans_move = transVector(move); position[0] = position[0] + step*trans_move[0]; position[1] = position[1] + step*trans_move[1]; position[2] = position[2] + step*trans_move[2]; } public void setTransMatrix() { for (int i = 0; i < 3; i++) { coordiTrans[0][i] = x[i]; coordiTrans[1][i] = y[i]; coordiTrans[2][i] = z[i]; } } public float[] transVector(float[] v) { return multiplyMatrixInVector(coordiTrans, v); }  
      and in the main class i have this:
       
      public void keyPressed(KeyEvent e) { if (e.getKeyCode()== KeyEvent.VK_ESCAPE) { System.exit(0); //player move } else if (e.getKeyCode()== KeyEvent.VK_W) { //front //moveAmount[2] += -0.1f; player.playerMoving(0, 0, 1); } else if (e.getKeyCode()== KeyEvent.VK_S) { //back //moveAmount[2] += 0.1f; player.playerMoving(0, 0, -1); } else if (e.getKeyCode()== KeyEvent.VK_A) { //left //moveAmount[0] += -0.1f; player.playerMoving(-1, 0, 0); } else if (e.getKeyCode()== KeyEvent.VK_D) { //right //moveAmount[0] += 0.1f; player.playerMoving(1, 0, 0); } else if (e.getKeyCode()== KeyEvent.VK_E) { //moveAmount[0] += 0.1f; player.playerMoving(0, 1, 0); } else if (e.getKeyCode()== KeyEvent.VK_Q) { //moveAmount[0] += 0.1f; player.playerMoving(0, -1, 0); //camera move } else if (e.getKeyCode()== KeyEvent.VK_I) { //up player.cameraMoving(1, "x"); } else if (e.getKeyCode()== KeyEvent.VK_K) { //down player.cameraMoving(-1, "x"); } else if (e.getKeyCode()== KeyEvent.VK_L) { //right player.cameraMoving(-1, "y"); } else if (e.getKeyCode()== KeyEvent.VK_J) { //left player.cameraMoving(1, "y"); } else if (e.getKeyCode()== KeyEvent.VK_O) { //right round player.cameraMoving(-1, "z"); } else if (e.getKeyCode()== KeyEvent.VK_U) { //left round player.cameraMoving(1, "z"); } }  
      finallt found it.... i confused with the transformation matrix row and col. thanks anyway!
    • By Lewa
      So, i'm currently trying to implement an SSAO shader from THIS tutorial and i'm running into a few issues here.
      Now, this SSAO method requires view space positions and normals. I'm storing the normals in my deferred renderer in world-space so i had to do a conversion and reconstruct the position from the depth buffer.
      And something there goes horribly wrong (which has probably to do with worldspace to viewspace transformations).
      (here is the full shader source code if someone wants to take a look at it)
      Now, i suspect that the normals are the culprit.
      vec3 normal = ((uNormalViewMatrix*vec4(normalize(texture2D(sNormals, vTexcoord).rgb),1.0)).xyz); "sNormals" is a 2D texture which stores the normals in world space in a RGB FP16 buffer.
      Now i can't use the camera viewspace matrix to transform the normals into viewspace as the cameras position isn't set at (0,0,0), thus skewing the result.
      So what i did is to create a new viewmatrix specifically for this normal without the position at vec3(0,0,0);
      //"camera" is the camera which was used for rendering the normal buffer renderer.setUniform4m(ressources->shaderSSAO->getUniform("uNormalViewMatrix"), glmExt::createViewMatrix(glm::vec3(0,0,0),camera.getForward(),camera.getUp())//parameters are (position,forwardVector,upVector) ); Though i have the feeling this is the wrong approach. Is this right or is there a better/correct way of transforming a world space normal into viewspace?
    • By HawkDeath
      Hi,
      I'm trying mix two textures using own shader system, but I have a problem (I think) with uniforms.
      Code: https://github.com/HawkDeath/shader/tree/test
      To debug I use RenderDocs, but I did not receive good results. In the first attachment is my result, in the second attachment is what should be.
      PS. I base on this tutorial https://learnopengl.com/Getting-started/Textures.


    • By norman784
      I'm having issues loading textures, as I'm clueless on how to handle / load images maybe I missing something, but the past few days I just google a lot to try to find a solution. Well theres two issues I think, one I'm using Kotlin Native (EAP) and OpenGL wrapper / STB image, so I'm not quite sure wheres the issue, if someone with more experience could give me some hints on how to solve this issue?
      The code is here, if I'm not mistaken the workflow is pretty straight forward, stbi_load returns the pixels of the image (as char array or byte array) and you need to pass those pixels directly to glTexImage2D, so a I'm missing something here it seems.
      Regards
    • By Hashbrown
      I've noticed in most post processing tutorials several shaders are used one after another: one for bloom, another for contrast, and so on. For example: 
      postprocessing.quad.bind() // Effect 1 effect1.shader.bind(); postprocessing.texture.bind(); postprocessing.quad.draw(); postprocessing.texture.unbind(); effect1.shader.unbind(); // Effect 2 effect2.shader.bind(); // ...and so on postprocessing.quad.unbind() Is this good practice, how many shaders can I bind and unbind before I hit performance issues? I'm afraid I don't know what the good practices are in open/webGL regarding binding and unbinding resources. 
      I'm guessing binding many shaders at post processing is okay since the scene has already been updated and I'm just working on a quad and texture at that moment. Or is it more optimal to put shader code in chunks and bind less frequently? I'd love to use several shaders at post though. 
      Another example of what I'm doing at the moment:
      1) Loop through GameObjects, bind its phong shader (send color, shadow, spec, normal samplers), unbind all.
      2) At post: bind post processor quad, and loop/bind through different shader effects, and so on ...
      Thanks all! 
    • By phil67rpg
      void collision(int v) { collision_bug_one(0.0f, 10.0f); glutPostRedisplay(); glutTimerFunc(1000, collision, 0); } void coll_sprite() { if (board[0][0] == 1) { collision(0); flag[0][0] = 1; } } void erase_sprite() { if (flag[0][0] == 1) { glColor3f(0.0f, 0.0f, 0.0f); glBegin(GL_POLYGON); glVertex3f(0.0f, 10.0f, 0.0f); glVertex3f(0.0f, 9.0f, 0.0f); glVertex3f(1.0f, 9.0f, 0.0f); glVertex3f(1.0f, 10.0f, 0.0f); glEnd(); } } I am using glutTimerFunc to wait a small amount of time to display a collision sprite before I black out the sprite. unfortunately my code only blacks out the said sprite without drawing the collision sprite, I have done a great deal of research on the glutTimerFunc and  animation.
    • By Lewa
      So, i stumbled upon the topic of gamma correction.
      https://learnopengl.com/Advanced-Lighting/Gamma-Correction
      So from what i've been able to gather: (Please correct me if i'm wrong)
      Old CRT monitors couldn't display color linearly, that's why gamma correction was nessecary. Modern LCD/LED monitors don't have this issue anymore but apply gamma correction anyway. (For compatibility reasons? Can this be disabled?) All games have to apply gamma correction? (unsure about that) All textures stored in file formats (.png for example) are essentially stored in SRGB color space (as what we see on the monitor is skewed due to gamma correction. So the pixel information is the same, the percieved colors are just wrong.) This makes textures loaded into the GL_RGB format non linear, thus all lighting calculations are wrong You have to always use the GL_SRGB format to gamma correct/linearise textures which are in SRGB format  
      Now, i'm kinda confused how to proceed with applying gamma correction in OpenGL.
      First of, how can i check if my Monitor is applying gamma correction? I noticed in my monitor settings that my color format is set to "RGB" (can't modify it though.) I'm connected to my PC via a HDMI cable. I'm also using the full RGB range (0-255, not the 16 to ~240 range)
       
      What i tried to do is to apply a gamma correction shader shown in the tutorial above which looks essentially like this: (it's a postprocess shader which is applied at the end of the renderpipeline)
      vec3 gammaCorrection(vec3 color){ // gamma correction color = pow(color, vec3(1.0/2.2)); return color; } void main() { vec3 color; vec3 tex = texture2D(texture_diffuse, vTexcoord).rgb; color = gammaCorrection(tex); outputF = vec4(color,1.0f); } The results look like this:
      No gamma correction:
      With gamma correction:
       
      The colors in the gamma corrected image look really wased out. (To the point that it's damn ugly. As if someone overlayed a white half transparent texture. I want the colors to pop.)
      Do i have to change the textures from GL_RGB to GL_SRGB in order to gamma correct them in addition to applying the post process gamma correction shader? Do i have to do the same thing with all FBOs? Or is this washed out look the intended behaviour?
    • By OneKaidou
      Hi
       
      I am trying to program shadow volumes and i stumbled upon an artifact which i can not find the cause for.
      I generate the shadow volumes using a geometry shader with reversed extrusion (projecting the lightfacing triangles to infinity) and write the stencil buffer according to z-fail. The base of my code is the "lighting" chapter from learnopengl.com, where i extended the shader class to include geometry shader. I also modified the "lightingshader" to draw the ambient pass when "pass" is set to true and the diffuse/ specular pass when set to false. For easier testing i added a view controls to switch on/off the shadow volumes' color rendering or to change the cubes' position, i made the lightnumber controllable and changed the diffuse pass to render green for easier visualization of my problem.
       
      The first picture shows the rendered scene for one point light, all cubes and the front cube's shadow volume is the only one created (intentional). Here, all is rendered as it should be with all lit areas green and all areas inside the shadow volume black (with the volume's sides blended over).

      If i now turn on the shadow volumes for all the other cubes, we get a bit of a mess, but its also obvious that some areas that were in shadow before are now erroneously lit (for example the first cube to the right from the originaly shadow volumed cube). From my testing the areas erroneously lit are the ones where more than one shadow volume marks the area as shadowed.

      To check if a wrong stencil buffer value caused this problem i decided to change the stencil function for the diffuse pass to only render if the stencil is equal to 2. As i repeated this approach with different values for the stencil function i found out that if i set the value equal to 1 or any other uneven value the lit and shadowed areas are inverted and if i set it to 0 or any other even value i get the results shown above.
      This lead me to believe that the value and thus the stencil buffer values may be clamped to [0,1] which would also explain the artifact, because twice in shadow would equal in no shadow at all, but from what i found on the internet and from what i tested with
      GLint stencilSize = 0; glGetFramebufferAttachmentParameteriv(GL_DRAW_FRAMEBUFFER, GL_STENCIL, GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE, &stencilSize); my stencilsize is 8 bit, which should be values within [0,255].
      Does anyone know what might be the cause for this artifact or the confusing results with other stencil functions?
       
      // [the following code includes all used gl* functions, other parts are due to readability partialy excluded] // glfw: initialize and configure // ------------------------------ glfwInit(); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 4); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // glfw window creation // -------------------- GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL); if (window == NULL) { cout << "Failed to create GLFW window" << endl; glfwTerminate(); return -1; } glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); glfwSetCursorPosCallback(window, mouse_callback); glfwSetScrollCallback(window, scroll_callback); // tell GLFW to capture our mouse glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED); // glad: load all OpenGL function pointers // --------------------------------------- if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { cout << "Failed to initialize GLAD" << endl; return -1; } // ==================================================================================================== // window and functions are set up // ==================================================================================================== // configure global opengl state // ----------------------------- glEnable(GL_DEPTH_TEST); glEnable(GL_CULL_FACE); // build and compile our shader program [...] // set up vertex data (and buffer(s)) and configure vertex attributes [...] // shader configuration [...] // render loop // =========== while (!glfwWindowShouldClose(window)) { // input processing and fps calculation[...] // render // ------ glClearColor(0.1f, 0.1f, 0.1f, 1.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glDepthMask(GL_TRUE); //enable depth writing glDepthFunc(GL_LEQUAL); //avoid z-fighting //draw ambient component into color and depth buffer view = camera.GetViewMatrix(); projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f); // setting up lighting shader for ambient pass [...] // render the cubes glBindVertexArray(cubeVAO); for (unsigned int i = 0; i < 10; i++) { //position cube [...] glDrawArrays(GL_TRIANGLES, 0, 36); } //------------------------------------------------------------------------------------------------------------------------ glDepthMask(GL_FALSE); //disable depth writing glEnable(GL_BLEND); glBlendFunc(GL_ONE, GL_ONE); //additive blending glEnable(GL_STENCIL_TEST); //setting up shadowShader and lightingShader [...] for (int light = 0; light < lightsused; light++) { glDepthFunc(GL_LESS); glClear(GL_STENCIL_BUFFER_BIT); //configure stencil ops for front- and backface to write according to z-fail glStencilOpSeparate(GL_FRONT, GL_KEEP, GL_DECR_WRAP, GL_KEEP); //-1 for front-facing glStencilOpSeparate(GL_BACK, GL_KEEP, GL_INCR_WRAP, GL_KEEP); //+1 for back-facing glStencilFunc(GL_ALWAYS, 0, GL_TRUE); //stencil test always passes if(hidevolumes) glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE); //disable writing to the color buffer glDisable(GL_CULL_FACE); glEnable(GL_DEPTH_CLAMP); //necessary to render SVs into infinity //draw SV------------------- shadowShader.use(); shadowShader.setInt("lightnr", light); int nr; if (onecaster) nr = 1; else nr = 10; for (int i = 0; i < nr; i++) { //position cube[...] glDrawArrays(GL_TRIANGLES, 0, 36); } //-------------------------- glDisable(GL_DEPTH_CLAMP); glEnable(GL_CULL_FACE); glStencilFunc(GL_EQUAL, 0, GL_TRUE); //stencil test passes for ==0 so only for non shadowed areas glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP); //keep stencil values for illumination glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE); //enable writing to the color buffer glDepthFunc(GL_LEQUAL); //avoid z-fighting //draw diffuse and specular pass lightingShader.use(); lightingShader.setInt("lightnr", light); // render the cubes for (unsigned int i = 0; i < 10; i++) { //position cube[...] glDrawArrays(GL_TRIANGLES, 0, 36); } } glDisable(GL_BLEND); glDepthMask(GL_TRUE); //enable depth writing glDisable(GL_STENCIL_TEST); //------------------------------------------------------------------------------------------------------------------------ // also draw the lamp object(s) [...] // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.) // ------------------------------------------------------------------------------- glfwSwapBuffers(window); glfwP } // optional: de-allocate all resources once they've outlived their purpose: // ------------------------------------------------------------------------ glDeleteVertexArrays(1, &cubeVAO); glDeleteVertexArrays(1, &lightVAO); glDeleteBuffers(1, &VBO); // glfw: terminate, clearing all previously allocated GLFW resources. // ------------------------------------------------------------------ glfwTerminate(); return 0;  
    • By Green_Baron
      Hi,
      i am self teaching me graphics and oo programming and came upon this:
      My Window class creates an input handler instance, the glfw user pointer is redirected to that object and methods there do the input handling for keyboard and mouse. That works. Now as part of the input handling i have an orbiting camera that is controlled by mouse movement. GLFW_CURSOR_DISABLED is set as proposed in the glfw manual. The manual says that in this case the cursor is automagically reset to the window's center. But if i don't reset it manually with glfwSetCursorPos( center ) mouse values seem to add up until the scene is locked up.
      Here are some code snippets, mostly standard from tutorials:
      // EventHandler m_eventHandler = new EventHandler( this, glm::vec3( 0.0f, 5.0f, 0.0f ), glm::vec3( 0.0f, 1.0f, 0.0f ) ); glfwSetWindowUserPointer( m_window, m_eventHandler ); m_eventHandler->setCallbacks(); Creation of the input handler during window creation. For now, the camera is part of the input handler, hence the two vectors (position, up-vector).  In future i'll take that functionally out into an own class that inherits from the event handler.
      void EventHandler::setCallbacks() { glfwSetCursorPosCallback( m_window->getWindow(), cursorPosCallback ); glfwSetKeyCallback( m_window->getWindow(), keyCallback ); glfwSetScrollCallback( m_window->getWindow(), scrollCallback ); glfwSetMouseButtonCallback( m_window->getWindow(), mouseButtonCallback ); } Set callbacks in the input handler.
      // static void EventHandler::cursorPosCallback( GLFWwindow *w, double x, double y ) { EventHandler *c = reinterpret_cast<EventHandler *>( glfwGetWindowUserPointer( w ) ); c->onMouseMove( (float)x, (float)y ); } Example for the cursor pos callback redirection to a class method.
      // virtual void EventHandler::onMouseMove( float x, float y ) { if( x != 0 || y != 0 ) { // @todo cursor should be set automatically, according to doc if( m_window->isCursorDisabled() ) glfwSetCursorPos( m_window->getWindow(), m_center.x, m_center.y ); // switch up/down because its more intuitive m_yaw += m_mouseSensitivity * ( m_center.x - x ); m_pitch += m_mouseSensitivity * ( m_center.y - y ); // to avoid locking if( m_pitch > 89.0f ) m_pitch = 89.0f; if( m_pitch < -89.0f ) m_pitch = -89.0f; // Update Front, Right and Up Vectors updateCameraVectors(); } } // onMouseMove() Mouse movement processor method. The interesting part is the manual reset of the mouse position that made the thing work ...
      // straight line distance between the camera and look at point, here (0,0,0) float distance = glm::length( m_target - m_position ); // Calculate the camera position using the distance and angles float camX = distance * -std::sin( glm::radians( m_yaw ) ) * std::cos( glm::radians( m_pitch) ); float camY = distance * -std::sin( glm::radians( m_pitch) ); float camZ = -distance * std::cos( glm::radians( m_yaw ) ) * std::cos( glm::radians( m_pitch) ); // Set the camera position and perspective vectors m_position = glm::vec3( camX, camY, camZ ); m_front = glm::vec3( 0.0, 0.0, 0.0 ) - m_position; m_up = m_worldUp; m_right = glm::normalize( glm::cross( m_front, m_worldUp ) ); glm::lookAt( m_position, m_front, m_up ); Orbiting camera vectors calculation in updateCameraVectors().
      Now, for my understanding, as the glfw manual explicitly states that if cursor is disabled then it is reset to the center, but my code only works if it is reset manually, i fear i am doing something wrong. It is not world moving (only if there is a world to render :-)), but somehow i am curious what i am missing.
       
      I am not a professional programmer, just a hobbyist, so it may well be that i got something principally wrong :-)
      And thanks for any hints and so ...
       
  • Advertisement
  • Popular Now

  • Forum Statistics

    • Total Topics
      631355
    • Total Posts
      2999512
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

Participate in the game development conversation and more when you create an account on GameDev.net!

Sign me up!