float3 Camera::transform_raster_to_world(float raster_x, float raster_y)
{
float3 D, P;
if(type == CAMERA_PERSPECTIVE) {
D = transform_perspective(&rastertocamera,
make_float3(raster_x, raster_y, 0.0f));
float3 Pclip = normalize(D);
P = make_float3(0.0f, 0.0f, 0.0f);
/* TODO(sergey): Aperture support? */
P = transform_point(&cameratoworld, P);
D = normalize(transform_direction(&cameratoworld, D));
/* TODO(sergey): Clipping is conditional in kernel, and hence it could
* be mistakes in here, currently leading to wrong camera-in-volume
* detection.
*/
P += nearclip * D / Pclip.z;
}
else if(type == CAMERA_ORTHOGRAPHIC) {
D = make_float3(0.0f, 0.0f, 1.0f);
/* TODO(sergey): Aperture support? */
P = transform_perspective(&rastertocamera,
make_float3(raster_x, raster_y, 0.0f));
P = transform_point(&cameratoworld, P);
D = normalize(transform_direction(&cameratoworld, D));
}
else {
assert(!"unsupported camera type");
}
return P;
}
float Camera::world_to_raster_size(float3 P)
{
if(type == CAMERA_ORTHOGRAPHIC) {
return min(len(full_dx), len(full_dy));
}
else if(type == CAMERA_PERSPECTIVE) {
/* Calculate as if point is directly ahead of the camera. */
float3 raster = make_float3(0.5f*width, 0.5f*height, 0.0f);
float3 Pcamera = transform_perspective(&rastertocamera, raster);
/* dDdx */
float3 Ddiff = transform_direction(&cameratoworld, Pcamera);
float3 dx = len_squared(full_dx) < len_squared(full_dy) ? full_dx : full_dy;
float3 dDdx = normalize(Ddiff + dx) - normalize(Ddiff);
/* dPdx */
float dist = len(transform_point(&worldtocamera, P));
float3 D = normalize(Ddiff);
return len(dist*dDdx - dot(dist*dDdx, D)*D);
}
else {
// TODO(mai): implement for CAMERA_PANORAMA
assert(!"pixel width calculation for panoramic projection not implemented yet");
}
return 1.0f;
}
float3 DiagSplit::project(Patch *patch, float2 uv)
{
float3 P;
patch->eval(&P, NULL, NULL, uv.x, uv.y);
if(params.camera)
P = transform_perspective(¶ms.camera->worldtoraster, P);
return P;
}
void Camera::update()
{
if(!need_update)
return;
/* Full viewport to camera border in the viewport. */
Transform fulltoborder = transform_from_viewplane(viewport_camera_border);
Transform bordertofull = transform_inverse(fulltoborder);
/* ndc to raster */
Transform screentocamera;
Transform ndctoraster = transform_scale(width, height, 1.0f) * bordertofull;
/* raster to screen */
Transform screentondc = fulltoborder * transform_from_viewplane(viewplane);
Transform screentoraster = ndctoraster * screentondc;
Transform rastertoscreen = transform_inverse(screentoraster);
/* screen to camera */
if(type == CAMERA_PERSPECTIVE)
screentocamera = transform_inverse(transform_perspective(fov, nearclip, farclip));
else if(type == CAMERA_ORTHOGRAPHIC)
screentocamera = transform_inverse(transform_orthographic(nearclip, farclip));
else
screentocamera = transform_identity();
Transform cameratoscreen = transform_inverse(screentocamera);
rastertocamera = screentocamera * rastertoscreen;
cameratoraster = screentoraster * cameratoscreen;
cameratoworld = matrix;
screentoworld = cameratoworld * screentocamera;
rastertoworld = cameratoworld * rastertocamera;
ndctoworld = rastertoworld * ndctoraster;
/* note we recompose matrices instead of taking inverses of the above, this
* is needed to avoid inverting near degenerate matrices that happen due to
* precision issues with large scenes */
worldtocamera = transform_inverse(matrix);
worldtoscreen = cameratoscreen * worldtocamera;
worldtondc = screentondc * worldtoscreen;
worldtoraster = ndctoraster * worldtondc;
/* differentials */
if(type == CAMERA_ORTHOGRAPHIC) {
dx = transform_direction(&rastertocamera, make_float3(1, 0, 0));
dy = transform_direction(&rastertocamera, make_float3(0, 1, 0));
}
else if(type == CAMERA_PERSPECTIVE) {
dx = transform_perspective(&rastertocamera, make_float3(1, 0, 0)) -
transform_perspective(&rastertocamera, make_float3(0, 0, 0));
dy = transform_perspective(&rastertocamera, make_float3(0, 1, 0)) -
transform_perspective(&rastertocamera, make_float3(0, 0, 0));
}
else {
dx = make_float3(0.0f, 0.0f, 0.0f);
dy = make_float3(0.0f, 0.0f, 0.0f);
}
dx = transform_direction(&cameratoworld, dx);
dy = transform_direction(&cameratoworld, dy);
need_update = false;
need_device_update = true;
need_flags_update = true;
}
