Bi tp 5Nm hc 2014 - 2015 Lu : Tt c cc bi tp u phi VIT TAY

CU 1:Bit rng th tch nhn ca camera c thit lp bng hm:

glOrtho(-1.2, 1.2, -1.2, 1.2, 0.1, 100);

Gi s hm DrawTeapot() v m tr c trng tm trng vi gc ta , vi m nm trn trc z dng, quai m nm trn trc z m.

Vi mi hnh v di y, hy chn tham s thch hp cho hm gluLookAt(...)glMatrixMode(GL_MODELVIEW);

glLoadIdentity();

gluLookAt(.);

DrawTeapot();

Hnh 1

Hnh 2

Hnh 3 Hnh 4

Hnh 5

CU 2:

Cho mt camera c v tr mt nhn (view reference point) E = (4, 4, 4), vector n v n nm trn ng thng x = y = z, vector n v u nm trong mt phng x = z, mt phng chiu (view plan) vung gc vi ng thng x = y = z v i qua im (8, 8, 8) (xem hnh v).

a) Tm ba vector u, v, n ca h ta camera.

b) Tm ma trn V bin i t ta th gii sang ta camera.

c) Tm ma trn M bin i t ta th gii sang ta trn mt phng chiu ca camera. Lu , cn phi chia lm hai trng hp : php chiu trc giao v php chiu phi cnh.

CU 3:

c trang 271 - 273 trong cun sch Interactive Computer Graphics A Top-Down Approach Using OpenGL.

Gi s ta dng nhng cu lnh sau thit lp th tch nhn:

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

glOrtho(-2.5, 1.5, -2.3, 2.7, 0.3, 300);

a) Hy tm ma trn chiu (projection matrix) bin i th tch nhn thnh th tch nhn chun.b) Hy nu ra 2 cch lm khc (yu cu vit cu lnh), thit lp c th tch nhn ging nh th tch nhn trn.

CU 4: c trang 273-276 trong cun sch Interactive Computer Graphics A Top-Down Approach Using OpenGL.

Gi s ta s dng php chiu xin vi cc gc (=1350 , (=450. Mt phng gn nm cch mt nhn 1, mt phng xa nm cch mt nhn 101. Mt phng chiu trng vi mt phng gn. Th tch nhn l mt hnh hp xin ABCDEFGH, vi mt ABCD nm trn mt phng chiu, vi cc ta nh sau (trong h ta camera): A = (-2.5, 1.5, -1), B = (1.5, 1.5, -1), C = (1.5, -2.5, -1), D = (-2.5, -2.5,- 1).

a) Tnh ta cc nh E, F, G, Hb) Tm ma trn bin i th tch nhn ABCDEFGH (hnh hp xin), thnh th th tch nhn l hnh hp ng

c) Tm ma trn chiu bin i th tch nhn ABCDEFGH (hnh hp xin), thnh th tch nhn chun.

CU 5:Cho t din ABCD trong khng gian i tng (Object Space) nh sau:A (1, 0, 0), B (-1, -1, 1), C (-1, 1, 1), D (-1, 0, -1)

Cc nh ca t din c bin i vo khng gian th gii (World Space) bng cch thc hin ln lt cc php bin i sau:

Quay quanh trc Z mt gc 90 ngc chiu kim ng h.

Phng to hai ln theo c 3 trc ta (vi tm ca php bin i l gc ta ): S(2, 2, 2)

Tnh tin theo trc X : T(2, 0, 0)

S dng hm gluLookAt() thit lp Camera vi tham s nh sau:

gluLookAt(-10, 0, 10, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

Thit lp php chiu phi cnh (Perspective Viewing) bng hm glFrustum() vi cc tham s nh sau:

glFrustum(-5, 5, -5, 5, 5, 15);1) Tnh ma trn Model (Model Matrix) chuyn cc nh t khng gian i tng vo khng gian th gii2) Tnh ma trn View (View Matrix) chuyn cc nh t khng gian th gii vo khng gian Camera3) Tnh ma trn Model-View (Model-View Matrix) chuyn t khng gian i tng vo khng gian Camera.

4) Tnh ma trn chiu (Projection Matrix) a cc nh vo khng gian ct

5) Tnh ta trong khng gian th gii, khng gian Camera v khng gian ct ca hai nh B v D.y

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