+ /* fill pattern offset with a distinctive pattern */\r
+ for (i=0;i < vga_state.vga_width;i++) {\r
+ o = (i >> 2) + pattern_ofs;\r
+ vga_write_sequencer(0x02/*map mask*/,1 << (i&3));\r
+ for (j=0;j < vga_state.vga_height;j++,o += vga_state.vga_stride)\r
+ vga_state.vga_graphics_ram[o] = (i^j)&15; // VRL samples put all colors in first 15!\r
+ }\r
+\r
+ /* starting coords. note: this technique is limited to x coordinates of multiple of 4 */\r
+ x = 0;\r
+ y = 0;\r
+\r
+ /* do it */\r
+ omemptr = vga_state.vga_graphics_ram; // save original mem ptr\r
+ while (1) {\r
+ /* stop animating if the user hits ENTER */\r
+ if (kbhit()) {\r
+ if (getch() == 13) break;\r
+ }\r
+\r
+ /* render box bounds. y does not need modification, but x and width must be multiple of 4 */\r
+ if (x >= overdraw) rx = (x - overdraw) & (~3);\r
+ else rx = 0;\r
+ if (y >= overdraw) ry = (y - overdraw);\r
+ else ry = 0;\r
+ h = vrl_header->height + overdraw + y - ry;\r
+ w = (x + vrl_header->width + (overdraw*2) + 3/*round up*/ - rx) & (~3);\r
+ if ((rx+w) > vga_state.vga_width) w = vga_state.vga_width-rx;\r
+ if ((ry+h) > vga_state.vga_height) h = vga_state.vga_height-ry;\r
+\r
+ /* block copy pattern to where we will draw the sprite */\r
+ vga_setup_wm1_block_copy();\r
+ o2 = offscreen_ofs;\r
+ o = pattern_ofs + (ry * vga_state.vga_stride) + (rx >> 2); // source offscreen\r
+ for (i=0;i < h;i++,o += vga_state.vga_stride,o2 += (w >> 2)) vga_wm1_mem_block_copy(o2,o,w >> 2);\r
+ /* must restore Write Mode 0/Read Mode 0 for this code to continue drawing normally */\r
+ vga_restore_rm0wm0();\r
+\r
+ /* replace VGA stride with our own and mem ptr. then sprite rendering at this stage is just (0,0) */\r
+ vga_state.vga_draw_stride_limit = (vga_state.vga_width + 3/*round up*/ - x) >> 2;\r
+ vga_state.vga_draw_stride = w >> 2;\r
+ vga_state.vga_graphics_ram = omemptr + offscreen_ofs;\r
+\r
+ /* then the sprite. note modding ram ptr means we just draw to (x&3,0) */\r
+ draw_vrl1_vgax_modex(x-rx,y-ry,vrl_header,vrl_lineoffs,buffer+sizeof(*vrl_header),bufsz-sizeof(*vrl_header));\r
+\r
+ /* restore ptr */\r
+ vga_state.vga_graphics_ram = omemptr;\r
+\r
+ /* block copy to visible RAM from offscreen */\r
+ vga_setup_wm1_block_copy();\r
+ o = offscreen_ofs; // source offscreen\r
+ o2 = (ry * vga_state.vga_stride) + (rx >> 2); // dest visible (original stride)\r
+ for (i=0;i < h;i++,o += vga_state.vga_draw_stride,o2 += vga_state.vga_stride) vga_wm1_mem_block_copy(o2,o,w >> 2);\r
+ /* must restore Write Mode 0/Read Mode 0 for this code to continue drawing normally */\r
+ vga_restore_rm0wm0();\r
+\r
+ /* restore stride */\r
+ vga_state.vga_draw_stride_limit = vga_state.vga_draw_stride = vga_state.vga_stride;\r
+\r
+ /* step */\r
+ x += xdir;\r
+ y += ydir;\r
+ if (x >= (vga_state.vga_width - 1) || x == 0)\r
+ xdir = -xdir;\r
+ if (y >= (vga_state.vga_height - 1) || y == 0)\r
+ ydir = -ydir;\r
+ }\r
+ }\r
+\r
+ /* another handy "demo" effect using VGA write mode 1.\r
+ * we can take what's on screen and vertically squash it like an old analog TV set turning off. */\r
+ {\r
+ unsigned int blank_line_ofs = (vga_state.vga_stride * vga_state.vga_height * 2);\r
+ unsigned int copy_ofs = (vga_state.vga_stride * vga_state.vga_height);\r
+ unsigned int display_ofs = 0x0000;\r
+ unsigned int i,y,soh,doh,dstart;\r
+ unsigned int dh_blankfill = 8;\r
+ unsigned int dh_step = 8;\r
+ uint32_t sh,dh,yf,ystep;\r
+\r
+ /* copy active display (0) to offscreen buffer (0x4000) */\r
+ vga_state.vga_draw_stride_limit = vga_state.vga_draw_stride = vga_state.vga_stride;\r
+ vga_setup_wm1_block_copy();\r
+ vga_wm1_mem_block_copy(copy_ofs,display_ofs,vga_state.vga_stride * vga_state.vga_height);\r
+ vga_restore_rm0wm0();\r
+\r
+ /* need a blank line as well */\r
+ for (i=0;i < vga_state.vga_stride;i++) vga_state.vga_graphics_ram[i+blank_line_ofs] = 0;\r
+\r
+ sh = dh = vga_state.vga_height;\r
+ while (dh >= dh_step) {\r
+ /* stop animating if the user hits ENTER */\r
+ if (kbhit()) {\r
+ if (getch() == 13) break;\r
+ }\r
+\r
+ /* wait for vsync end */\r
+ vga_wait_for_vsync_end();\r
+\r
+ /* what scalefactor to use for stretching? */\r
+ ystep = (0x10000UL * sh) / dh;\r
+ dstart = (vga_state.vga_height - dh) / 2; // center the squash effect on screen, otherwise it would squash to top of screen\r
+ doh = display_ofs;\r
+ soh = copy_ofs;\r
+ yf = 0;\r
+ y = 0;\r
+\r
+ /* for performance, keep VGA in write mode 1 the entire render */\r
+ vga_setup_wm1_block_copy();\r
+\r
+ /* blank lines */\r
+ if (dstart >= dh_blankfill) y = dstart - dh_blankfill;\r
+ else y = 0;\r
+ doh = vga_state.vga_stride * y;\r
+\r
+ while (y < dstart) {\r
+ vga_wm1_mem_block_copy(doh,blank_line_ofs,vga_state.vga_stride);\r
+ doh += vga_state.vga_stride;\r
+ y++;\r
+ }\r
+\r
+ /* draw */\r
+ while (y < (dh+dstart)) {\r
+ soh = copy_ofs + ((yf >> 16UL) * vga_state.vga_stride);\r
+ vga_wm1_mem_block_copy(doh,soh,vga_state.vga_stride);\r
+ doh += vga_state.vga_stride;\r
+ yf += ystep;\r
+ y++;\r
+ }\r
+\r
+ /* blank lines */\r
+ while (y < vga_state.vga_height && y < (dh+dstart+dh_blankfill)) {\r
+ vga_wm1_mem_block_copy(doh,blank_line_ofs,vga_state.vga_stride);\r
+ doh += vga_state.vga_stride;\r
+ y++;\r
+ }\r
+\r
+ /* done */\r
+ vga_restore_rm0wm0();\r
+\r
+ /* wait for vsync */\r
+ vga_wait_for_vsync();\r
+\r
+ /* make it shrink */\r
+ dh -= dh_step;\r
+ if (dh < 40) dh_step = 1;\r
+ }\r