Advertisement

Ray from screen coord (in worldspace) to farplane

Started by September 30, 2015 04:15 PM
24 comments, last by _WeirdCat_ 9 years ago

ok I guess I found you're problem:

matrix.m[8] = -forward.x;
matrix.m[9] = -forward.y;
matrix.m[10] = -forward.z;

you have the forward in the opposite direction (this is the right way I do it like this too but references and actual related math don't do like this) so you need to negate the z value of the starting point after calculating it

code will be like:


TRay RayFromScreen(int x, int y, int sw, int sh, float fov, float z_near, float z_far, float aspect)
{

	vec2 NormalizedCoordinates;
	NormalizedCoordinates.x = (float(x) / float(sw) ) * 2.0 - 1.0;
	NormalizedCoordinates.y = (float(y) / float(sh) ) * 2.0 - 1.0;

	vec4 NDC=vec4(NormalizedCoordinates.x, NormalizedCoordinates.y,-1.0, 1.0); //z=-1 because its on near plane

	TRay res;
	mat4 ProjectionMatrix = CAM_PROJECTION;
	ProjectionMatrix.Transpose();
	mat4 ViewMatrix = CAM_VIEW;
	ViewMatrix.Transpose();
	mat4 pvm = ProjectionMatrix*ViewMatrix;
	pvm.Inverse();
	res.start=pvm*NDC;
	res.start.z=res.start.z*-1.0f;

	vec3 RayDirection=res.start-FPP_CAM->pos;
	RayDirection=(RayDirection/RayDirection.z)*(z_far-z_near);//normalize by Z resize the z by farZ-nearZ so that it hits the far plane

	res.end=res.start+RayDirection;

return 

gluperspective function accepts fov as fovy not fov for xz plane

Advertisement

I'm not getting your point, maybe chat'd be better

for gluPerspecitve you define a fov angle which is between top and bottom clipplanes,

yes I understand that, but where are you getting with that? it's supposed to be like that in other functions too, you have fovy, D3D does the same too

proper results....

This topic is closed to new replies.

Advertisement