I am working on OpenGL 2D image viewer for microscopic tissue investigation. I have to simulate the tissue back light in the microscope. In microscope, there is a back light on which the tissue slide is positioned. This gives a bright view of the tissue. The back light rays are almost parallel for the tissue viewport.
For my image viewer, I am rendering image tiles as textures. But not getting how to simulate the back light. I tried OpenGL diffuse light but it is not giving back light experience. Thing that I don't understand is how to place the light source in the texture background. My viewer is just 2D viewer.
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I am trying to create a scene in opengl and I am having trouble with my lighting. I believe it is something to do with translating my models from the origin of the world into their respective places.
I only have 1 light in my scene placed on the right in the centre of the world, however you can see the light on the wall at the front of the scene.
I have wrote my own shaders. I suspect that I'm calculating the lighting too early as it seems that it is being calculated before the models are being translated around the world, that or I am using local coordinates rather than world coordinates (I think thats right anyway...).
(please ignore the glass, they are using a global light and a different shader)
Does anyone know if this is indeed the case or where would be the best place to find a solution.
Below is how I call rendering my models.
glUseProgram(modelShader);
//center floor mat
if (floorMat)
{
glUniformMatrix4fv(modelShader_modelMatrixLocation, 1, GL_FALSE, (GLfloat*)&(modelTransform.M));
floorMat->setTextureForModel(carpetTexture);
floorMat->renderTexturedModel();
}
https://www.youtube.com/watch?annotation_id=annotation_1430411783&feature=iv&index=86&list=PLRwVmtr-pp06qT6ckboaOhnm9FxmzHpbY&src_vid=NH68sIdF-48&v=P3DQXzyjswQ
Turns out I was not calculating the lighting in world space.
Rather than using the transposed modelworldposition I was just using the plain vertex position
Hi im trying to create a shader for my 3D models with materials and fog. Everything works fine but the light direction. I'm not sure what to set it to so I used a fixed value, but when I rotate my 3D model (which is a simple textured sphere) the light rotates with it. I want to change my code so that my light stays in one place according to the camera and not the object itself. I have tried multiplying the view matrix by the input normals but the same result occurs.
Also, should I be setting the light direction according to the camera instead?
EDIT: removed pastebin link since that is against the rules...
Use camera depended values just for transforming vertex pos to view and projected position (needed in shaders for clipping and rasterizer stage). The video cards needs to know, where to draw your pixel.
For lighting you normally pass additional to the camera transformed value the world position of the vertex and the normal in world position to the needed shader stages (i.e pixel shader stage for phong lighting).
So you can set your light position, or better light direction in world space coordinate system as global variable to your shaders. With that the lighting is independent of the camera view position.
If you want to have a effect like using a flashlight. You can set the lightposition to camera position, and light direction to your look direction. So the bright parts are always in the center of your viewing frustum.
good luck
I'm trying to add a skybox to the world/camera/game and I don't know how to go about it. If someone could give me some guidance on how to apply it, it would be much appreciated.
I have already loaded the skybox, I just don't know how to draw it properly so it will fit around the camera as it moves.
I have managed to texture a sort of cube, which might be close to a skybox but then it's only visible from the outside. Once you enter the cube, you can't see it from the inside. Perhaps if I could invert the cube's faces, it will show when I'm inside the cube and I can make it larger?
From outside the cube looking at it
From inside looking out
I had a similar problem a few weeks back, if you are looking for some pseudo code I think I may be able to help. First of all using a cube isn't the best idea when rendering as your box won't look natural, map it to a sphere for a smooth effect.
Create a bounding sphere around your viewer that moves relative to your camera
Apply the texture on that sphere, this will give the impression that the sky is moving relative to you
When you are drawing, disable your z-buffer and frustum (assuming you're using any culling algorithm) this will allow the sky box to be drawn but will ensure terrain is drawn over the top of the sky box when depth sort algorithms are performed by OpenGL.
Note: Don't forget to re-enable the z-buffer after the sky box has been drawn, otherwise your terrain elements will appear outside of the sphere, meaning you will only see the Sky box.
I recently wrote a basic terrain engine in DirectX but the principals are fairly similar, if you'd like to view the repo you can find it here
Check out line 286 in this file to see how the Skybox is rendered, then also visit the SkyBox implementation file to see how it is constructed, and the SkyShader implementation file to see how the texture is mapped to the sphere, the main method to be concerned with in the shader file is SetShaderParameters()
In terms of moving the skybox relative to your camera, simply set the WVP matrix of your skybox to that of your camera, and then tweak the x, y, z planes of the skybox to your liking.
Extra If you are going to implement multi-player aspects, just disable back-face rendering for the sphere, then each player can see their SkyBox but opponents cannot. Alternatively you create one large sphere around the world
Hope that helps - if you need anymore help just ask, I know this stuff can be fairly dense at first:)
What I'm doing to render some beautiful city lights on the night side of the Earth is to render a second sphere mesh on top of the Earth mesh, then I set the city lights texture on it with 200% ambient light so they become very bright, and make the alpha channel of the dds texture file transparent so the Earth texture can be seen behind on the original Earth mesh.
The result is this pretty nice effect:
http://s24.postimg.org/gpqg8a491/screenshot_2.png
This is the code for the mesh holding the lights texture:
d3ddev->LightEnable(0, FALSE);
d3ddev->SetRenderState(D3DRS_AMBIENT, D3DCOLOR_XRGB(200, 200, 200));
d3ddev->SetRenderState(D3DRS_ALPHABLENDENABLE, TRUE);
d3ddev->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA);
d3ddev->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_DESTALPHA);
//d3ddev->SetRenderState(D3DRS_ALPHAREF, (DWORD)0x0000008f);
d3ddev->SetRenderState(D3DRS_ALPHATESTENABLE, FALSE);
d3ddev->SetTexture(0, earth_lights);
However the bad thing is that the lights also show in the day side, always, and that's pretty bad.
How can I achieve a similar result but with the lights not showing in the day side? Texture blending? Shaders?
I'm doing a 3D asteroids game in windows (using OpenGL and GLUT) where you move in space through a bunch of obstacles and survive. I'm looking for a way to set an image background against the boring bg color options. I'm new to OpenGL and all i can think of is to texture map a sphere and set it to a ridiculously large radius. What is the standard way of setting image bg in a 3d game?
The standard method is to draw two texture mapped triangles, whose coordinates are x,y = +-1, z=0, w=1 and where both camera and perspective matrices are set to identity matrix.
Of course in the context of a 'space' game, where one could want the background to rotate, the natural choice is to render a cube with cubemap (perhaps showing galaxies). As the depth buffering is turned off during the background rendering, the cube doesn't even have to be "infinitely" large. A unit cube will do, as there is no way to find out how close the camera is to the object.