Jump to content
  • Advertisement
Sign in to follow this  

Head tracking projection matrix

This topic is 3215 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, I have been mucking around re-writing Jonny Lee's wiimote vr desktop in c++. Could somebody please explain why, when you move your head CLOSER to the screen, the back wall appears FURTHER away?! Here is the code I am using to Render a single frame. headDist, headX, and headY are values for the head being tracked. They are respectivelt the distance of head from screen, head x position and headY position. //------------------------------------------------- void RenderFrame() { float screenAspect = (float)SCREEN_WIDTH / (float)SCREEN_HEIGHT; // clear the window d3ddev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0); d3ddev->BeginScene(); // begins the 3D scene // select which vertex format we are using d3ddev->SetFVF(CUSTOMFVF); // select the vertex buffer to display d3ddev->SetStreamSource(0, vertexBuffer, 0, sizeof(CUSTOMVERTEX)); RenderWorldTransform(screenAspect); if(world._wiimoteConnected) { RenderViewTransform(world.GetHeadX(), world.GetHeadY(), world.GetHeadDist()); RenderProjTransform(world.GetHeadX(), world.GetHeadY(), world.GetHeadDist(), screenAspect); } else { RenderViewTransform(0, 0, 90.0); RenderProjTransform(0, 0, 90.0, screenAspect); } d3ddev->EndScene(); // ends the 3D scene d3ddev->Present(NULL, NULL, NULL, NULL); // displays the created frame on the screen return; } void RenderWorldTransform(float screenAspect) { int NumberOfLines; float boxdepth; D3DXMATRIX matTranslate1; D3DXMATRIX matTranslate2; D3DXMATRIX matTranslate3; D3DXMATRIX matTranslate4; D3DXMATRIX matTranslate5; D3DXMATRIX matTranslate6; D3DXMATRIX matTranslate7; D3DXMATRIX matScale1; D3DXMATRIX matScale2; D3DXMATRIX matScale3; D3DXMATRIX matScale4; D3DXMATRIX matRot1; D3DXMATRIX matRot2; D3DXMATRIX flipY; boxdepth = 15; NumberOfLines = 18; D3DXMatrixTranslation(&matTranslate1, -0.5f, -0.5f, -1*boxdepth/2); D3DXMatrixTranslation(&matTranslate2, -0.5f, -0.5f, 0); D3DXMatrixTranslation(&matTranslate3, 0.5f * screenAspect, 0, -.5f*boxdepth/2); D3DXMatrixTranslation(&matTranslate4, -1.0f * screenAspect, 0, 0); D3DXMatrixTranslation(&matTranslate5, 0, 0.5f, -0.5f*boxdepth/2); D3DXMatrixTranslation(&matTranslate6, 0, -1.0f, 0); D3DXMatrixTranslation(&matTranslate7, -0.5f, -0.25f, 3.0f); D3DXMatrixScaling(&matScale1, screenAspect, 1.0f, 1.0f); D3DXMatrixScaling(&matScale2, 1 * boxdepth / 2, 1.0f, 1.0f); D3DXMatrixScaling(&matScale3,screenAspect , 1 * boxdepth / 2, 1.0f); D3DXMatrixScaling(&matScale4, screenAspect/2, screenAspect/2, 1.0f); D3DXMatrixRotationY(&matRot1, D3DXToRadian(90)); D3DXMatrixRotationX(&matRot2, D3DXToRadian(90)); D3DXMatrixRotationY(&flipY, D3DXToRadian(180)); //draw back wall d3ddev->SetTransform(D3DTS_WORLD, &(matTranslate1 * matScale1) ); d3ddev->DrawPrimitive(D3DPT_LINELIST,0,NumberOfLines); //draw left wall d3ddev->SetTransform(D3DTS_WORLD, &(matTranslate2 * matScale2 * matRot1 * matTranslate3) ); d3ddev->DrawPrimitive(D3DPT_LINELIST, 0, NumberOfLines); //draw right wall d3ddev->SetTransform(D3DTS_WORLD, &(matTranslate2 * matScale2 * matRot1 * matTranslate3 * matTranslate4) ); d3ddev->DrawPrimitive(D3DPT_LINELIST, 0, NumberOfLines); //draw top wall d3ddev->SetTransform(D3DTS_WORLD, &(matTranslate2 * matScale3 * matRot2 * matTranslate5) ); d3ddev->DrawPrimitive(D3DPT_LINELIST, 0, NumberOfLines); //draw bottom wall d3ddev->SetTransform(D3DTS_WORLD, &(matTranslate2 * matScale3 * matRot2 * matTranslate5 * matTranslate6) ); d3ddev->DrawPrimitive(D3DPT_LINELIST, 0, NumberOfLines); } void RenderProjTransform(float headX, float headY, float headDist, float screenAspect) { D3DXMATRIX matProjection; float nearPlane = .05f; D3DXMatrixPerspectiveOffCenterLH(&matProjection, nearPlane*((-.5f * screenAspect) + headX)/headDist,//Minimum x-value of the view volume. nearPlane*((.5f * screenAspect) + headX)/headDist, //Maximum x-value of the view volume. nearPlane*(-.5f - headY)/headDist, //Minimum y-value of the view volume. nearPlane*(.5f - headY)/headDist, //Maximum y-value of the view volume. nearPlane, //Minimum z-value of the view volume. 100); //Maximum z-value of the view volume. d3ddev->SetTransform(D3DTS_PROJECTION, &matProjection); } void RenderViewTransform(float headX, float headY, float headDist) { D3DXMATRIX matView; // the view transform matrix D3DXMatrixLookAtLH(&matView, &D3DXVECTOR3 (headX, headY, headDist), // the camera position &D3DXVECTOR3 (headX, headY, 0.0f), // the look-at position &D3DXVECTOR3 (0.0f, 1.0f, 0.0f)); // the up direction d3ddev->SetTransform(D3DTS_VIEW, &matView); // set the view transform to matView } //-------------------------------------------------- [Edited by - joe90p on December 27, 2009 5:19:18 AM]

Share this post

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

  • Advertisement

Important Information

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

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!