Sign in to follow this  
xlope01

DX11 Picking triangle

Recommended Posts

xlope01    215

Based on this tutorial I have try to make it work with triangles with no success.

this tutorial is demonstrating how to how to do picking on the a sphere, so in theory if i take the rayOrigin and rayDirection can work with a  triangle.(without the MatrixTranslation for the center of the sphere), but don't because something needs to be changed regarding the rayOrigin / rayDirection.

all i want is to get the intersection point on the triangle.
 

struct triangle {
        D3DXVECTOR3 V0;
        D3DXVECTOR3 V1;
        D3DXVECTOR3 V2;
    };
struct Ray {
            D3DXVECTOR3 P0;
            D3DXVECTOR3 P1;
    };
...
intersect3D_RayTriangle(Ray, triangle, out intersection point);//this method works fine, if you don't put the ray data that comes from this tutorial

 

Edited by xlope01

Share this post


Link to post
Share on other sites
xlope01    215

Maybe i didn't make my self clear I already have a ray/trianlge intersection method that is working, the problem is the ray that is created by mouse clicking is some how wrong.

TestIntersection(int visibleMouseX, int visibleMouseY)
{
		float pointX, pointY;
		D3DXMATRIX projectionMatrix, viewMatrix, inverseViewMatrix, worldMatrix, translateMatrix, inverseWorldMatrix;
		D3DXVECTOR3 direction, origin, rayOrigin, rayDirection;


		// Move the mouse cursor coordinates into the -1 to +1 range.
		pointX = ((2.0f * (float)visibleMouseX) / (float)m_ResolutionWidth) - 1.0f;
		pointY = (((2.0f * (float)visibleMouseY) / (float)m_ResolutionHight) - 1.0f) * -1.0f;
		
		// Adjust the points using the projection matrix to account for the aspect ratio of the viewport.
		m_D3D->GetProjectionMatrix(projectionMatrix);
		pointX = pointX / projectionMatrix._11;
		pointY = pointY / projectionMatrix._22;

		// Get the inverse of the view matrix.
		m_Camera->GetViewMatrix(viewMatrix);
		D3DXMatrixInverse(&inverseViewMatrix, NULL, &viewMatrix);

		// Calculate the direction of the picking ray in view space.
		direction.x = (pointX * inverseViewMatrix._11) + (pointY * inverseViewMatrix._21) + inverseViewMatrix._31;
		direction.y = (pointX * inverseViewMatrix._12) + (pointY * inverseViewMatrix._22) + inverseViewMatrix._32;
		direction.z = (pointX * inverseViewMatrix._13) + (pointY * inverseViewMatrix._23) + inverseViewMatrix._33;

		// Get the origin of the picking ray which is the position of the camera.
		origin = m_Camera->GetPosition();

		// Get the world matrix and translate to the location of the sphere.
		m_D3D->GetWorldMatrix(worldMatrix);
		//D3DXMatrixTranslation(&translateMatrix, 1800.0f, 20.0f, 1900.0f);
		D3DXMatrixMultiply(&worldMatrix, &worldMatrix, &translateMatrix); 

		// Now get the inverse of the translated world matrix.
		D3DXMatrixInverse(&inverseWorldMatrix, NULL, &worldMatrix);

		// Now transform the ray origin and the ray direction from view space to world space.
		D3DXVec3TransformCoord(&rayOrigin, &origin, &inverseWorldMatrix);
		D3DXVec3TransformNormal(&rayDirection, &direction, &inverseWorldMatrix);

		// Normalize the ray direction.
		D3DXVec3Normalize(&rayDirection, &rayDirection);


		Ray r;
		r.P0 = rayOrigin;
		r.P1 = rayDirection;
		triangle tri;
		tri.V0 = D3DXVECTOR3(1.0f, 0.0f, 1.0f);
		tri.V1 = D3DXVECTOR3(100.0f, 0.0f, 100.0f);
		tri.V2 = D3DXVECTOR3(0.0f, 0.0f, 100.0f);
		D3DXVECTOR3 intersect;
		intersect3D_RayTriangle(r, tri, &intersect);

		return intersect;
}

Share this post


Link to post
Share on other sites
xlope01    215

"r.P1" sounds like a point to me, and yet you're passing in a unit vector instead.

 

I don't know you could expect any useful advice without telling anyone what's wrong.

 

I take rayOrigin as point 1 and rayDirection as point 2 crating a line, and i believe that is not the correct way to do it unsure.png ?

Share this post


Link to post
Share on other sites
unbird    8335
Nicely spotted, Pink Horror.

Edit: If your triangle intersection function defines a ray as two points, then you need to give it two points, not a point and a direction (vector).

Picking (or any collision/intersection test for that matter) need to happen in the same space. I think rastertek - although the code presumably works for the sphere - is making a bit of a fuss with the spaces. E.g. using the inverse world transform goes from world to local (model) space, not from view to world. Check if you got that right. Edited by unbird

Share this post


Link to post
Share on other sites
Norman Barrows    7179

for ray generation, i used the code from the raypick example in directx. works great. hooked it up to a ray-plane test for the plane y=0 to do skycam picks onto a world map for RTS type camera views.

 

i've noted that rastertek, while good, sometimes does weird stuff - like the code at the start of their "calculating frustum cull planes" examples.  always compare their stuff to at least one other source if unsure.

Share this post


Link to post
Share on other sites
xlope01    215

ok i get it I will use the vector "rayDirection", however all the methods( triangle intersection ) I find take as input a ray that require point 1 and point 2.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Similar Content

    • By gsc
      Hi! I am trying to implement simple SSAO postprocess. The main source of my knowledge on this topic is that awesome tutorial.
      But unfortunately something doesn't work... And after a few long hours I need some help. Here is my hlsl shader:
      float3 randVec = _noise * 2.0f - 1.0f; // noise: vec: {[0;1], [0;1], 0} float3 tangent = normalize(randVec - normalVS * dot(randVec, normalVS)); float3 bitangent = cross(tangent, normalVS); float3x3 TBN = float3x3(tangent, bitangent, normalVS); float occlusion = 0.0; for (int i = 0; i < kernelSize; ++i) { float3 samplePos = samples[i].xyz; // samples: {[-1;1], [-1;1], [0;1]} samplePos = mul(samplePos, TBN); samplePos = positionVS.xyz + samplePos * ssaoRadius; float4 offset = float4(samplePos, 1.0f); offset = mul(offset, projectionMatrix); offset.xy /= offset.w; offset.y = -offset.y; offset.xy = offset.xy * 0.5f + 0.5f; float sampleDepth = tex_4.Sample(textureSampler, offset.xy).a; sampleDepth = vsPosFromDepth(sampleDepth, offset.xy).z; const float threshold = 0.025f; float rangeCheck = abs(positionVS.z - sampleDepth) < ssaoRadius ? 1.0 : 0.0; occlusion += (sampleDepth <= samplePos.z + threshold ? 1.0 : 0.0) * rangeCheck; } occlusion = saturate(1 - (occlusion / kernelSize)); And current result: http://imgur.com/UX2X1fc
      I will really appreciate for any advice!
    • By isu diss
       I'm trying to code Rayleigh part of Nishita's model (Display Method of the Sky Color Taking into Account Multiple Scattering). I get black screen no colors. Can anyone find the issue for me?
       
      #define InnerRadius 6320000 #define OutterRadius 6420000 #define PI 3.141592653 #define Isteps 20 #define Ksteps 10 static float3 RayleighCoeffs = float3(6.55e-6, 1.73e-5, 2.30e-5); RWTexture2D<float4> SkyColors : register (u0); cbuffer CSCONSTANTBUF : register( b0 ) { float fHeight; float3 vSunDir; } float Density(float Height) { return exp(-Height/8340); } float RaySphereIntersection(float3 RayOrigin, float3 RayDirection, float3 SphereOrigin, float Radius) { float t1, t0; float3 L = SphereOrigin - RayOrigin; float tCA = dot(L, RayDirection); if (tCA < 0) return -1; float lenL = length(L); float D2 = (lenL*lenL) - (tCA*tCA); float Radius2 = (Radius*Radius); if (D2<=Radius2) { float tHC = sqrt(Radius2 - D2); t0 = tCA-tHC; t1 = tCA+tHC; } else return -1; return t1; } float RayleighPhaseFunction(float cosTheta) { return ((3/(16*PI))*(1+cosTheta*cosTheta)); } float OpticalDepth(float3 StartPosition, float3 EndPosition) { float3 Direction = normalize(EndPosition - StartPosition); float RayLength = RaySphereIntersection(StartPosition, Direction, float3(0, 0, 0), OutterRadius); float SampleLength = RayLength / Isteps; float3 tmpPos = StartPosition + 0.5 * SampleLength * Direction; float tmp; for (int i=0; i<Isteps; i++) { tmp += Density(length(tmpPos)-InnerRadius); tmpPos += SampleLength * Direction; } return tmp*SampleLength; } static float fExposure = -2; float3 HDR( float3 LDR) { return 1.0f - exp( fExposure * LDR ); } [numthreads(32, 32, 1)] //disptach 8, 8, 1 it's 256 by 256 image void ComputeSky(uint3 DTID : SV_DispatchThreadID) { float X = ((2 * DTID.x) / 255) - 1; float Y = 1 - ((2 * DTID.y) / 255); float r = sqrt(((X*X)+(Y*Y))); float Theta = r * (PI); float Phi = atan2(Y, X); static float3 Eye = float3(0, 10, 0); float ViewOD = 0, SunOD = 0, tmpDensity = 0; float3 Attenuation = 0, tmp = 0, Irgb = 0; //if (r<=1) { float3 ViewDir = normalize(float3(sin(Theta)*cos(Phi), cos(Theta),sin(Theta)*sin(Phi) )); float ViewRayLength = RaySphereIntersection(Eye, ViewDir, float3(0, 0, 0), OutterRadius); float SampleLength = ViewRayLength / Ksteps; //vSunDir = normalize(vSunDir); float cosTheta = dot(normalize(vSunDir), ViewDir); float3 tmpPos = Eye + 0.5 * SampleLength * ViewDir; for(int k=0; k<Ksteps; k++) { float SunRayLength = RaySphereIntersection(tmpPos, vSunDir, float3(0, 0, 0), OutterRadius); float3 TopAtmosphere = tmpPos + SunRayLength*vSunDir; ViewOD = OpticalDepth(Eye, tmpPos); SunOD = OpticalDepth(tmpPos, TopAtmosphere); tmpDensity = Density(length(tmpPos)-InnerRadius); Attenuation = exp(-RayleighCoeffs*(ViewOD+SunOD)); tmp += tmpDensity*Attenuation; tmpPos += SampleLength * ViewDir; } Irgb = RayleighCoeffs*RayleighPhaseFunction(cosTheta)*tmp*SampleLength; SkyColors[DTID.xy] = float4(Irgb, 1); } }  
    • By amadeus12
      I made my obj parser
      and It also calculate tagent space for normalmap.
      it seems calculation is wrong..
      any good suggestion for this?
      I can't upload my pics so I link my question.
      https://gamedev.stackexchange.com/questions/147199/how-to-debug-calculating-tangent-space
      and I uploaded my code here


      ObjLoader.cpp
      ObjLoader.h
    • By Alessandro Pozzer
      Hi guys, 

      I dont know if this is the right section, but I did not know where to post this. 
      I am implementing a day night cycle on my game engine and I was wondering if there was a nice way to interpolate properly between warm colors, such as orange (sunset) and dark blue (night) color. I am using HSL format.
      Thank  you.
    • By thefoxbard
      I am aiming to learn Windows Forms with the purpose of creating some game-related tools, but since I know absolutely nothing about Windows Forms yet, I wonder:
      Is it possible to render a Direct3D 11 viewport inside a Windows Form Application? I see a lot of game editors that have a region of the window reserved for displaying and manipulating a 3D or 2D scene. That's what I am aiming for.
      Otherwise, would you suggest another library to create a GUI for game-related tools?
       
      EDIT:
      I've found a tutorial here in gamedev that shows a solution:
      Though it's for D3D9, I'm not sure if it would work for D3D11?
       
  • Popular Now