Determining texture coordinates in computer graphics

Claim 1

A method for obtaining a texture coordinate TC1 of a point Q' to be displayed by a computer, the method comprsing: obtaining signals representing a modified texture coordinate TC1' and a value w' such that TC1=TC1'/w'; providing the signal representing the value w' to a circuit which includes a look-up table storing inverses of selected values; the circuit obtaining an inverse value from the look-up table and using interpolation to generate an inverse value 1/w; the circuit multiplying the modified texture coordinate TC1' by 1/w and obtaining the texture coordinate TC1; using the texture coordinate TC1 to obtain a texel value, and using the texel value to modify an image of the point Q', and displaying the modified image of the point Q' on a computer device which displays computer graphics images; wherein: the point Q' is in a segment Q 1 'Q 2 ' which is an image of a segment Q 1 Q 2 , wherein Q 1 ' is the image of a point Q 1 having world coordinates (x 1 ,y 1 ,z 1 ), and Q 2 ' is the image of a point Q 2 having world coordinates (x 2 ,y 2 ,z 2 ), and wherein the point Q 1 ' has screen coordinates (x 1 /z 1 /y 1 /z 1 ) and the point Q 2 ' has screen coordinates (x 2 /z 2 , y 2 /z 2 ); w'=(1-t)/z 1 +t/z 2 wherein t is such that the point Q' has screen coordinates (1-t)*(x 1 /z 1 , y 1 /z 1 )+t(x 2 /z 2 , y 2 /z 2 ); TC1 is either the u coordinate or the v coordinate of the point Q'; and TC1' is either (1-t)u 1 /z 1 +tu 2 /z 2 or (1-t)v 1 /z 1 +tv 2 /z 2 , wherein (u 1 ,v 1 ) are texture coordinates of the point Q 1 ' and (u 2 ,v 2 ) are texture coordinates of the point Q 2 '.

Claim 2

A method for obtaining a texture coordinate TC1 of a point Q' to be displayed by a computer, the method comprsing: obtaining signals representing a modified texture coordinate TC1' and a value w' such that TC1=TC1'/w'; providing the signal representing the value w' to a circuit which includes a look-up table storing inverses of selected values; the circuit obtaining an inverse value from the look-up table and using interpolation to generate an inverse value 1/w; the circuit multiplying the modified texture coordinate TC1' by 1/w and obtaining the texture coordinate TC1; using the texture coordinate TC1 to obtain a texel value, and using the texel value to modify an image of the point Q', and displaying the modified image of the point Q' on a computer device which displays computer graphics images; wherein: the point Q' is in a segment Q 1 'Q 2 ' which is an image of a segment Q 1 Q 2 , wherein Q 1 ' is the image of a point Q 1 having world coordinates (x 1 ,y 1 ,z 1 ), and Q 2 ' is the image of a point Q 2 having world coordinates (x 2 ,y 2 ,z 2 ), and wherein the point Q 1 ' has screen coordinates (x 1 /z 1 /y 1 /z 1 ) and the point Q 2 ' has screen coordinates (x 2 /z 2 , y 2 /z 2 ); w'=(1-t)/z 1 +t/z 2 wherein t is such that the point Q' has screen coordinates (1-t)*(x 1 /z 1 , y 1 /z 1 )+t(x 2 /z 2 , y 2 /z 2 ); TC1 is either the u coordinate or the v coordinate of the point Q'; and TC1' is either (1-t)u 1 /z 1 +tu 2 /z 2 or (1-t)v 1 /z 1 +tv 2 /z 2 , wherein (u 1 ,v 1 ) are texture coordinates of the point Q 1 ' and (u 2 ,v 2 ) are texture coordinates of the point Q 2 '.

Claim 8

A system for obtaining a texture coordinate TC1 of a point Q' to be displayed by a computer, the system comprising: a terminal for receiving signals representing a modified texture coordinate TC1' and a value w' such that TC1=TC1'/w'; a circuit connected to the terminal, for receiving the signal representing the value w', the circuit comprising a look-up table storing inverses of selected values, the circuit being for obtaining an inverse value from the look-up table and for using interpolation to generate an inverse value 1/w, and for multiplying the modified texture coordinate TC1' by 1/w and obtaining the texture coordinate TC1, wherein: the point Q' is in a segment Q 1 'Q 2 ' which is an image of a segment Q 1 Q 2 , wherein Q 1 ' is the image of a point Q 1 having world coordinates (x 1 , y 1 , z 1 ), and Q 2 ' is the image of a point Q 2 having world coordinates (x 2 , y 2 , z 2 ), and wherein the point Q 1 ' has screen coordinates (x1/z 1 , y 1 /z 1 ) and the point Q 2 ' has screen coordinates (x 2 /z 2 , y 2 /z 2 ); w'=(1-t)/z 1 +t/z 2 wherein t is such that the point Q' has screen coordinates (1-t)*(x 1 /z 1 , y 1 /z 1 )+t(x 2 /z 2 , y 2 /z 2 ); TC1 is either the u coordinate or the v coordinate of the point Q'; and TC1' is either (1-t)u 1 /z 1 +tu 2 /z 2 or (1-t)v 1 z 1 +tv 2 /z 2 , wherein (u 1 ,v 1 ) are texture coordinates of the point Q 1 ' and (u 2 ,v 2 ) are texture coordinates of the point Q 2 '.

Claim 9

A system for obtaining a texture coordinate TC1 of a point Q' to be displayed by a computer, the system comprising: a terminal for receiving signals representing a modified texture coordinate TC1' and a value w' such that TC1=TC1'/w'; a circuit connected to the terminal, for receiving the signal representing the value w', the circuit comprising a look-up table storing inverses of selected values, the circuit being for obtaining an inverse value from the look-up table and for using interpolation to generate an inverse value 1/w, and for multiplying the modified texture coordinate TC1' by 1/w and obtaining the texture coordinate TC1, wherein: the point Q' is in a segment Q 1 'Q 2 ' which is an image of a segment Q 1 Q 2 , wherein Q 1 ' is the image of a point Q 1 having world coordinates (x 1 , y 1 , z 1 ), and Q 2 ' is the image of a point Q 2 having world coordinates (x 2 , y 2 , z 2 ), and wherein the point Q 1 ' has screen coordinates (x1/z 1 , y 1 /z 1 ) and the point Q 2 ' has screen coordinates (x 2 /z 2 , y 2 /z 2 ); w'=(1-t)/z 1 +t/z 2 wherein t is such that the point Q' has screen coordinates (1-t)*(x 1 /z 1 , y 1 /z 1 )+t(x 2 /z 2 , y 2 /z 2 ); TC1 is either the u coordinate or the v coordinate of the point Q'; and TC1' is either (1-t)u 1 /z 1 +tu 2 /z 2 or (1-t)v 1 z 1 +tv 2 /z 2 , wherein (u 1 ,v 1 ) are texture coordinates of the point Q 1 ' and (u 2 ,v 2 ) are texture coordinates of the point Q 2 '.

Claim 14

A system for obtaining a texture coordinate TC1 of a point Q' to be displayed by a computer, wherein TC1=TC1'/w', wherein TC1 is a modified texture coordinate, the system comprising: a first lookup table storing inverse values 1/w i of selected values w i which are in a a normalizer for receiving the signal w' and generating an index i for the first lookup table to obtain the signal 1/w wherein w is in the predetermined interval and w=w'*F for some factor F; an interpolation circuit for receiving the signal 1/w i from the lookup table, performing an interpolation, and generating the signal 1/w; and a result generation circuit for generating the texture coordinate TC1 from TC1' and 1/w, wherein the interpolation circuit comprises: a second lookup table for storing the values 1(w i w i+1 ) and providing one of these values in response to the index i; a multiplier for receiving the value 1/(w i w i+1 ) and for receiving from the normalizer a signal representative of the value (w-w i ) and for generating a signal representative of the product (w-w i )*{1/(w i w i+1 )}; and a subtractor for subtracting the mulliplier output from the output 1/w i of the first lookup table and thus generating the signal 1/w.

Claim 15

A system for obtaining a texture coordinate TC1 of a point Q' to be displayed by a computer, wherein TC1=TC1'/w', wherein TC1 is a modified texture coordinate, the system comprising: a first lookup table storing inverse values 1/w i of selected values w i which are in a a normalizer for receiving the signal w' and generating an index i for the first lookup table to obtain the signal 1/w wherein w is in the predetermined interval and w=w'*F for some factor F; an interpolation circuit for receiving the signal 1/w i from the lookup table, performing an interpolation, and generating the signal 1/w; and a result generation circuit for generating the texture coordinate TC1 from TC1' and 1/w, wherein the interpolation circuit comprises: a second lookup table for storing the values 1(w i w i+1 ) and providing one of these values in response to the index i; a multiplier for receiving the value 1/(w i w i+1 ) and for receiving from the normalizer a signal representative of the value (w-w i ) and for generating a signal representative of the product (w-w i )*{1/(w i w i+1 )}; and a subtractor for subtracting the mulliplier output from the output 1/w i of the first lookup table and thus generating the signal 1/w.

Claim 17

A method for generating an image of one or more objects by a computer graphics system, the one or more objects ircluding points Q 1 and Q 2 and a point Q in a segment Q 1 Q 2 , wherein the point Q, has world coordinates (x 1 , y 1 , z 1 ), the point Q 2 has world coordinates (x 2 , y 2 , z 2 ), and the point Q has world coordinates (x, y, z), the method comprising: obtaining first signals representing screen coordinates (x 1 ', y 1 ')=(x 1 /z 1 , y 1 /z 1 ) corresponding to the point Q 1 , screen coordinates (x 2 ', y 2 ')=(x 2 /z 2 , y 2 /z 2 ) corresponding to the point Q 2 , and screen coordinates (x', y')=(x/z, y/z) corresponding to the point Q; using the first signals to generate a second signal representing at least one of values t, 1-t such that: (x', y')=(1-t)*(x 1 ', y 1 ')+t(x 2 ', y 2 ') obtaining third signals representing modified texture coordinates TC1'=TC1 1 /z 1 , TC1 2 '=TC1 2 /z 2 , wherein TC 1 1 is a texture coordinate of the point Q 1 , and TC1 2 is a texture coordinate of the point Q 2 ; using the second and third signals to generate a fourth signal representing a value TC1'=(1-t)*TC1 1 '+t*TC1 2 '; obtaining fifth signals representing 1/z 1 and 1/z 2 ; using the second and fifth signals to generate a sixth signal representing a value w'=(1-t)/z 1 +t/z 2 ; using the fourth and sixth signals to generate a signal representing a value TC1=TC1'/w'; using TC1 as a texture coordinate of the point Q to determine a texture corresponding to the point Q, and modifying an image of the point Q with said texture, and displaying the modified image of the point Q on a computer device.

Claim 18

A method for generating an image of one or more objects by a computer graphics system, the one or more objects ircluding points Q 1 and Q 2 and a point Q in a segment Q 1 Q 2 , wherein the point Q, has world coordinates (x 1 , y 1 , z 1 ), the point Q 2 has world coordinates (x 2 , y 2 , z 2 ), and the point Q has world coordinates (x, y, z), the method comprising: obtaining first signals representing screen coordinates (x 1 ', y 1 ')=(x 1 /z 1 , y 1 /z 1 ) corresponding to the point Q 1 , screen coordinates (x 2 ', y 2 ')=(x 2 /z 2 , y 2 /z 2 ) corresponding to the point Q 2 , and screen coordinates (x', y')=(x/z, y/z) corresponding to the point Q; using the first signals to generate a second signal representing at least one of values t, 1-t such that: (x', y')=(1-t)*(x 1 ', y 1 ')+t(x 2 ', y 2 ') obtaining third signals representing modified texture coordinates TC1'=TC1 1 /z 1 , TC1 2 '=TC1 2 /z 2 , wherein TC 1 1 is a texture coordinate of the point Q 1 , and TC1 2 is a texture coordinate of the point Q 2 ; using the second and third signals to generate a fourth signal representing a value TC1'=(1-t)*TC1 1 '+t*TC1 2 '; obtaining fifth signals representing 1/z 1 and 1/z 2 ; using the second and fifth signals to generate a sixth signal representing a value w'=(1-t)/z 1 +t/z 2 ; using the fourth and sixth signals to generate a signal representing a value TC1=TC1'/w'; using TC1 as a texture coordinate of the point Q to determine a texture corresponding to the point Q, and modifying an image of the point Q with said texture, and displaying the modified image of the point Q on a computer device.