x68000:screen_control
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— | x68000:screen_control [2014/06/29 22:45] – eidis | ||
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+ | ====== Screen Control ====== | ||
+ | |||
+ | [p.161] | ||
+ | |||
+ | Screen Control mechanism, | ||
+ | In this chapter, it is explained about several screen modes, | ||
+ | |||
+ | ====== 1. Screen construction of X68000 ====== | ||
+ | |||
+ | |||
+ | | ||
+ | On the other hand, X68000 is designed for deeling with several requirement about " | ||
+ | window system with several character fonts, without overload of CPU. | ||
+ | |||
+ | | ||
+ | | ||
+ | |||
+ | [p.162] | ||
+ | |||
+ | {{: | ||
+ | |||
+ | These screens have respective characters and make it possible to be | ||
+ | variegated expression by using properly for purposes or using combined. | ||
+ | Here it is collected each of construction and characters, about every | ||
+ | graphic, | ||
+ | Figure 2(p.163) shows constructions of each screen, | ||
+ | |||
+ | [p.163] | ||
+ | |||
+ | {{: | ||
+ | |||
+ | [p.164] | ||
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+ | ====== 1-1 Graphic screen ====== | ||
+ | |||
+ | Graphic screen is suitable for the occasion such as paint soft or ray tracing soft that uses many colors.65536 colors at the same time is shown in this screen. | ||
+ | Else 65536 colors mode,it has 256 colors mode,16 colors mode.In all mode, | ||
+ | 1 dot on screen always shown by 1 word(16 bits). | ||
+ | When we draw figures ,bit arrays of data are easy understood when they are | ||
+ | virtical to screen, so it is also called " | ||
+ | We can define a color of the dot by writing color code in memory address | ||
+ | correspond to ordered dot position, and we can take the color code by reading the memory of the ordered dot position. | ||
+ | When we use more colors, | ||
+ | |||
+ | ====== 1-2 Text screen ====== | ||
+ | |||
+ | Text screen has the just opposite character of graphics screen. | ||
+ | By The name "Text screen" | ||
+ | but text screen of X68000 is a kind of graphics screens.It is useful that | ||
+ | we can put dots on free position or elase them. | ||
+ | The Difference of the text screen and graphic screen is that ,in text screen ,bit arrays are in horizontal direction.That is 1 word data correspond to horizontal 16 dots. | ||
+ | In graphic screen we must write 16 times to draw 16 dots even in monochrome mode,but in text screen we can write 1 time.So it is useful to show previouly prepareted patterns such as character patterns . | ||
+ | X68000 has 4 such text planes, and each plane corresponds to each bit of color code. Then max 16 colors selected from 65536 colors it can show. | ||
+ | |||
+ | [p.165] | ||
+ | |||
+ | ====== 1-3 BG screen ====== | ||
+ | |||
+ | BG(Back Ground)screen is a screen mainly made for game alike Sprite screen. | ||
+ | In game screen,it is usual not only moving characters but showing backgrounds such as cities or maps. | ||
+ | We can use text or graphic screens for such purpose,but in case of game, BG screen is made for more efficient screen control paying attention to using many alike patterns. | ||
+ | BG screen consists of 64x64 squares ,and 32x32 regions shown on display. | ||
+ | Each square has corrensponding memory area and when we write pattern number | ||
+ | (0-255), | ||
+ | We can show each pattern indivisually in wanted area, but BG can show at the same time 32x32=1024 pattern(but we can use 192 pattern). | ||
+ | X68000 has 2 BG screen and we can select where we want to show by 1 unit dot about each 2 screen indivisually.So we can scroll smoothly backgrounds. | ||
+ | |||
+ | ====== 1-4 Sprite screen ====== | ||
+ | |||
+ | Sprite shows defined patterns on free position of the screen. | ||
+ | X68000 can define 256 patterns (16dot x 16dot)and show max 128s. | ||
+ | (but 32s on a horizontal line).Graphic screen or Text screen point to | ||
+ | relative motion-less screen ,and sprite screen is confortable for the purpose | ||
+ | such as action games which moves quickly patternd characters. | ||
+ | If we try to such games on graphic screen or text screen,we must read the pattern data which a character moves to, and then we draw back the data after | ||
+ | moving a character other position. | ||
+ | By using sprite,such overlap is processed by hardware,so software only have to | ||
+ | write designation resister of sprite position, | ||
+ | " | ||
+ | of this Sprite function. | ||
+ | |||
+ | |||
x68000/screen_control.txt · Last modified: 2019/08/27 20:45 by 127.0.0.1