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  • frankiezafe 00:38 on 2017-10-19 Permalink | Reply
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    Editing ogre materials:

  • frankiezafe 23:24 on 2017-10-12 Permalink | Reply
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    (a bit more than a technical demo this time)
    After finishing the work on shadows, it was time to play with the different materials possibilities.

    To explain a bit what you are seeing:

    • at the top left, the 3 textures containing the shadow maps;
    • transparent walls (wireframes) are not take into account in the shadow map because they are using a specific material called invisible_for_shadows, i think the name is obvious;
    • the foggy volume above the ground is made of a stack of 25 thin boxes, using another cool material: solid_shadows_no_cast, they receive shadows but don’t cast them;
    • and the balls, using the solid_shadows material and having the standard behavior, but in wireframe, implying that fog is hollowed when you look through them.

    A cool feature is the ability to set the alpha of the shadows material per material. For the jelly fog, the material is looking like this:

    material screen_mat : solid_shadows_no_cast
        pass standard
          diffuse 0.6 0.7 0.95 0.2
          emissive 0.2 0.3 0.45 0.4
          depth_write off
          scene_blend alpha_blend
        pass pssm
          fragment_program_ref ShadowsPssm_pix
            param_named shadow_alpha float 0.2

    The speed control over the physic simulation (when everything freeze) is modifying the time multiplier of bullet. The call is looking like this:


    Complete projects is accessible in the engine, under samples/0.1/example.pssm_shadows.

    I need to rest a bit, it has been a harsh road to get this packed. The last part of the job is to ensure the compatibility low opengl versions!

  • frankiezafe 14:11 on 2017-10-11 Permalink | Reply
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    Ogre3d really deserves some attention to deliver its full potential. A good example is the management of different version of shaders in a single program. In the image here above, the graphical cards are very different: the laptop has a low-end integrated intel chipset, the workstation is working with a GTX 980. The supported opengl version: glsl120 max for the laptop, vp40 for the gtx.

    This information is dumped in terminal when the application starts, search for something like this:

    Supported Shader Profiles: arbfp1 arbvp1 fp20 fp30 fp40 glsl glsl100 glsl110 glsl120 gp4fp gp4gp gp4vp gpu_fp gpu_gp gpu_vp nvgp4 vp30 vp40

    Once identified, we can now prepare a program script to select shaders automatically.

    In the .material:

    material shader_tester
          fragment_program_ref tester_pix

    In the .program:

    fragment_program tester_pix_glsl glsl
      source tester_pix_120.glsl

    fragment_program tester_pix_glsl_330 glsl
      source tester_pix_330.glsl
      syntax fp40

    fragment_program tester_pix unified
      delegate tester_pix_glsl
      delegate tester_pix_glsl_330

    The crucial instruction here is the syntax definition in fragment_program tester_pix_glsl_330. The available flags are listed here: Declaring Vertex/Geometry/Fragment Programs. The fragment_program tester_pix_glsl has no syntax flag, it will be used as the default one.

    Shaders are stupidly simple in this case.


    void main() {
      gl_FragColor = vec4( 0,1,0,1 );


    #version 330
    void main() {
      gl_FragColor = vec4( 1,0,0,1 );

    And that’s it for the automatic selection of shaders in ogre.

  • frankiezafe 20:38 on 2017-10-10 Permalink | Reply
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    Visualisation of contact events in the engine. Wireframe objects are the actual physical objects. The small plain spheres are placed at the position of the contact (or the average of all points), and reacts to impulse. Impulse is one of the components of the forces applied on the objects while bullet resolves the world.


    • impulse > 1000: red material;
    • impulse > 1: yellow material;
    • by default: cyan material;
    • scale calculation: (3 + impulse * 0.00001) caps at 15.

    To be precise, the impulse used here is the delta of the previous and current impulse.

    The video shows only one of the 2 contact events you can retrieve from engine:

    • pairs: represents the relation between 2 objects in contact (visualised here);
    • per object: it is also possible to retrieve contacts for a specific object.

    In future version, I plan to enable specific pair listening (“i want to know when this specific object touch this other specific object”).

  • frankiezafe 15:53 on 2017-10-07 Permalink | Reply
    Tags: dilbert, , humor, image   

    source: http://dilbert.com/strip/2017-10-02

  • frankiezafe 19:50 on 2017-10-06 Permalink | Reply
    Tags: , pssm, , ,   

    Tech info: 3 splits, 4096, 2048 & 1024 maps, 2 pass materials on all objects, gpu: GTX 980.

    Working on an “easy” to deploy shadow system for the engine. The work now is to make the activation of these as simple as possible.

    For the moment, the activtion has to be done manually through many steps: loading specific resources, activating them, modification of the default PolymorphApplication methods, etc.

    To make it simplier, the resources should be placed in zip, like the PolymorphTrays.zip (containing the UI style), and loaded via standard methods.

    Just to mention, I discovered the “import” feature in ogre’s materials, just wonderful! To modify the appearence of the balls in the video, one just have to inherit from a complex material called two_pass_shadows declared in the shadow package, in shadows_pssm.material file.

    import * from “shadows_pssm.material”
    material ball_mat : two_pass_shadows
        pass standard
          diffuse 0.1 0.99 0.95 1.0
            texture retro.png
            colour_op alpha_blend

    see Script-Inheritance for details.

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