Jump to content
  • Advertisement
Sign in to follow this  
mikenovemberoscar

OpenGL GLSL Shaders?

This topic is 2589 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

Hello,

I recently wanted to dive into the realms of shader programming in GLSL on my OpenGL based application.
I borrowed some of [color="#000000"]swiftless' code on GLSL, and this works for simple stuff, like void main(void)
{

gl_FragColor = vec4(1.0,1.0,0.0,1.0);


}


but if I try to copy someone else's shader program (this was one for fog I found on the internet) to test if this really works errors pop up:

[source = cpp] [font="Courier"][Session started at 2011-05-02 11:03:37 +0100.][/font]********** VERTEX SHADER **********

varying float atten;

varying float fogFactor;

varying vec3 lightVec, viewVec;

attribute vec3 tangent;




void main(void)

{

gl_Position = ftransform();

gl_TexCoord[0] = gl_MultiTexCoord0.xy;



vec3 n = normalize(gl_NormalMatrix * gl_Normal);

vec3 t = normalize(gl_NormalMatrix * tangent);

vec3 b = cross(n, t);



vec3 vVertex = vec3(gl_ModelViewMatrix * gl_Vertex);

vec3 vLVec = gl_LightSource[0].position.xyz - vVertex;



atten = 1.0 / (1.0 + 0.00001 * dot(vLVec, vLVec));



vec3 vVec = -vVertex;

viewVec.x = dot(vVec, t);

viewVec.y = dot(vVec, b);

viewVec.z = dot(vVec, n);



lightVec.x = dot(vLVec, t);

lightVec.y = dot(vLVec, b);

lightVec.z = dot(vLVec, n);



const float LOG2 = 1.442695;

gl_FogFragCoord = length(vVertex);

fogFactor = exp2( -gl_Fog.density *

gl_Fog.density *

gl_FogFragCoord *

gl_FogFragCoord *

LOG2 );

fogFactor = clamp(fogFactor, 0.0, 1.0);

}




********** FRAGMENT SHADER **********




varying float atten;

varying float fogFactor;

varying vec3 lightVec, viewVec;

uniform sampler2D normalMap;

uniform sampler2D colorMap;

uniform sampler2D colorMap2;




void main (void)

{

vec3 lVec = normalize(lightVec);

vec3 vVec = normalize(viewVec);



vec4 base = texture2D(colorMap, gl_TexCoord[0]*2.0);

vec3 bump = normalize(texture2D(normalMap,

gl_TexCoord[0]*2.0).xyz*2.0-1.0);

vec4 base2 = texture2D(colorMap2, gl_TexCoord[0]*4.0);




float diffuse = max( dot(lVec, bump), 0.0 );

float specular = pow(clamp(dot(reflect(-vVec, bump), lVec), 0.0, 1.0),

gl_FrontMaterial.shininess );



vec4 vAmbient = gl_FrontLightProduct[0].ambient * base + (base2*0.4);

vec4 vDiffuse = gl_FrontLightProduct[0].diffuse * diffuse * base;

vec4 vSpecular = gl_FrontLightProduct[0].specular * specular;



vec4 finalColor = (vAmbient + vDiffuse + vSpecular) * atten;



gl_FragColor = mix(gl_Fog.color, finalColor, fogFactor );

}




shader 1 (test_vertex_shader.sfvs) compile error: ERROR: 0:9: 'assign' : cannot convert from '2-component vector of float' to '4-component vector of float'




shader 2 (glow.sffs) compile error: ERROR: 0:14: 'texture2D' : no matching overloaded function found

ERROR: 0:14: '=' : cannot convert from 'const float' to '4-component vector of float'

ERROR: 0:16: 'texture2D' : no matching overloaded function found

ERROR: 0:16: 'xyz' : field selection requires structure or vector on left hand side

ERROR: 0:15: '=' : cannot convert from 'const float' to '3-component vector of float'

ERROR: 0:17: 'texture2D' : no matching overloaded function found

ERROR: 0:17: '=' : cannot convert from 'const float'[/source]


Why is this happening? Is GLSL not general - purpose and cross application?
Considering my end goal would be to create a fullscreen 'glow' effect, how could I go about doing this? (I have to save the current screen to a texture then blur, add to the final scene, then render a fullscreen quad?)
Is there a complete reference for GLSL and how to use it in OpenGL?
How does GLSL work with OpenGL, is it a post-processing thing or what?

Thanks


mikey

Share this post


Link to post
Share on other sites
Advertisement
Thanks, but I already had read that particular document, and it still seems too compilcated! I'm not actually sure what exactly a shader is, how does it work, when is it 'applied', how is it applied, etc?

Share this post


Link to post
Share on other sites
GLSL is reasonably general purpose, but it's the same as anything else in computing - garbage in, garbage out. A shader has specifically defined inputs which much be provided by your program's code; if you don't provide them then they may have default or undefined values.

Share this post


Link to post
Share on other sites
GL_TEXTURE_2D

texture2D( texture, texCoord.st )

GL_TEXTURE_2D_ARRAY

texture2DArray( texture, texCoord.stp )

notice the coordinates are vec2 and vec3 respectively
that shader you just posted is full of mistakes :)
i can help you fix them, but youll learn alot from fixinf it yourself!

Share this post


Link to post
Share on other sites
Ah OK thanks, but I can't seem to find a complete reference for GLSL, They are all either constant lists or other stuff. This also leads back to the original question, what can be done in GLSL, what does it do? Should I write a program to play PONG in a quad? Is GLSL ONLY applied to textures or the whole screen?

Share this post


Link to post
Share on other sites
GLSL is the Shader language of OpenGL. Shaders in general let u calculate anything u want on the GPU, of course with an focus on graphic stuff. You can do with them anything u want like filters, Lighting effects, modifying geometry, ray tracing. With them u specify what should be display on your screen. With OpenGL u always render to a RenderTartget, if this target is a Texture or the screen depends what u want to do.

I would suggest u to do some OpenGL 3 tutorials, they will explain all the necessary stuff what u need to know.

Share this post


Link to post
Share on other sites
So I feed geometry, textures, etc to OpenGL, which creates a 2D texture which is then either rendered on the screen or modified using shaders, then rendered on the screen?

( glVertex, glVertex -> texture -> screen) ??
( glVertex, glVertex -> texture -> shader -> screen ) or??

But then how do vertex shaders work?

I'll have a squint at some OpenGL 3 Tutorials, thanks

Share this post


Link to post
Share on other sites
The code was likely written on a relaxed rules video card such as most modern Nvidia cards. The code has type mismatched errors all through. For instance, the texture error that says "ERROR: 0:16: 'texture2D' : no matching overloaded function found " is happening because a texture map in shader programming is a vec4, but the normals are vec3. To fix this particular error : add .xyz at the end of the function ----->vec3 bump = normalize(texture2D(normalMap, gl_TexCoord[0]*2.0).xyz*2.0-1.0).xyz;<----- This feeds only the first three parameters to the vec3 bump variable, eliminating one of your errors.

Share this post


Link to post
Share on other sites
a shader is a method for directly manipulating the (i) vertices of a model, (ii) the individual fragments of the model , as well as the texture map coordinates Once you format a model into the proper form and send it to the video card using openGL calls you can now alter the model on a much more subtle basis. Shader programs alter the lighting characteristics of the model by using lighting formulas which can be reconfigured and re-written so far as your ability and imagination allow. The vertex processor is also capable of moving the vertices of a model individually. For a few quick examples download the CG toolkit from nVidia ->> http://developer.nvidia.com/ The language is mostly the same as glsl but with some setup differences. You should study both cg as well glsl since they are compatible with one another in the same program and all the basic concepts are the same. Also visit http://www.codesampler.com/ , as well as http://nehe.gamedev.net/. Nehe uses mostly fixed function lighting but is full of excellent openGL material. Code sampler has many shader programs. Be sure to check the [font=Verdana, Arial, Helvetica, sans-serif][size=2]User Samples [/font] at the bottom of the openGL section. Look for the following-->> It will help get the point across of shaders[font=Verdana, Arial, Helvetica, sans-serif]

[/font]
[font=Verdana, Arial, Helvetica, sans-serif]//---------------------------------------------------------------//user samples @ codeSampler.com
Bump Mapping with GLSlang (OpenGL - C++) Author: [email="anudhyan@gmail.com"]Anudhyan Boral[/email]
//---------------------------------------------------------------

Follow the next link to see a vertex processor program which creates a wavy effect that is applied to a flat tessellated plane( the thumbnail you're looking for is a green wavy mesh)

http://nehe.gamedev.net/lesson.asp?index=10

It can be used for water, flags,capes or even grass blowing in the wind..

[/font]

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
      631354
    • Total Posts
      2999499
×

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!