mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-09-12 01:54:33 +00:00
251 lines
4.7 KiB
C
251 lines
4.7 KiB
C
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#include <string.h>
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typedef unsigned char byte;
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typedef signed char sbyte;
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typedef unsigned short word;
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word __at(0xa000) dvgram[0x1000];
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byte __at(0x8840) _dvgstart;
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volatile int __at(0x8100) mathbox_sum;
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sbyte __at(0x8102) mathbox_arg1;
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sbyte __at(0x8103) mathbox_arg2;
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byte __at(0x810f) mathbox_go_mul;
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//
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void main();
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void start() {
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__asm
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LD SP,#0x0
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DI
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__endasm;
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main();
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}
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int dvgwrofs; // write offset for DVG buffer
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inline word ___swapw(word j) {
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return ((j << 8) | (j >> 8));
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}
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inline void dvgreset() {
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dvgwrofs = 0;
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}
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inline void dvgstart() {
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_dvgstart = 0;
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}
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void dvgwrite(word w) {
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dvgram[dvgwrofs++] = w;
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}
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inline void VCTR(int dx, int dy, byte bright) {
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dvgwrite((dy & 0x1fff));
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dvgwrite(((bright & 7) << 13) | (dx & 0x1fff));
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}
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inline void SVEC(sbyte dx, sbyte dy, byte bright) {
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dvgwrite(0x4000 | (dx & 0x1f) | ((bright&7)<<5) | ((dy & 0x1f)<<8));
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}
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inline void JSRL(word offset) {
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dvgwrite(0xa000 | offset);
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}
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inline void JMPL(word offset) {
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dvgwrite(0xe000 | offset);
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}
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inline void RTSL() {
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dvgwrite(0xc000);
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}
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inline void CNTR() {
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dvgwrite(0x8000);
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}
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inline void HALT() {
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dvgwrite(0x2000);
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}
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inline void STAT(byte rgb, byte intens) {
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dvgwrite(0x6000 | ((intens & 0xf)<<4) | (rgb & 7));
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}
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inline void STAT_sparkle(byte intens) {
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dvgwrite(0x6800 | ((intens & 0xf)<<4));
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}
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inline void SCAL(word scale) {
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dvgwrite(0x7000 | scale);
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}
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enum {
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BLACK, BLUE, GREEN, CYAN, RED, MAGENTA, YELLOW, WHITE
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} Color;
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///
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typedef struct {
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sbyte m[3][3];
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} Matrix;
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typedef struct {
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sbyte x,y,z;
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} Vector8;
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typedef struct {
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int x,y,z;
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} Vector16;
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typedef struct {
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byte numverts;
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const Vector8* verts; // array of vertices
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const sbyte* edges; // array of vertex indices (edges)
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} Wireframe;
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void mat_identity(Matrix* m) {
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memset(m, 0, sizeof(*m));
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m->m[0][0] = 127;
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m->m[1][1] = 127;
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m->m[2][2] = 127;
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}
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inline void mul16(sbyte a, sbyte b) {
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mathbox_arg1 = a;
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mathbox_arg2 = b;
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mathbox_go_mul=0;
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}
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void vec_mat_transform(Vector16* dest, const Vector8* v, const Matrix* m) {
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byte i;
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int* result = &dest->x;
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const sbyte* mval = &m->m[0][0];
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for (i=0; i<3; i++) {
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mathbox_sum = 0;
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mul16(*mval++, v->x);
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mul16(*mval++, v->y);
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mul16(*mval++, v->z);
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*result++ = mathbox_sum;
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}
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}
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/*
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void vec_mat_transform2(Vector16* dest, const Vector8* v, const Matrix* m) {
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dest->x = v->x*m->m[0][0] + v->y*m->m[0][1] + v->z*m->m[0][2];
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dest->y = v->x*m->m[1][0] + v->y*m->m[1][1] + v->z*m->m[1][2];
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dest->z = v->x*m->m[2][0] + v->y*m->m[2][1] + v->z*m->m[2][2];
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}
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*/
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const sbyte sintbl[64] = {
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0, 3, 6, 9, 12, 16, 19, 22, 25, 28, 31, 34, 37, 40, 43, 46,
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49, 51, 54, 57, 60, 63, 65, 68, 71, 73, 76, 78, 81, 83, 85, 88,
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90, 92, 94, 96, 98, 100, 102, 104, 106, 107, 109, 111, 112, 113, 115, 116,
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117, 118, 120, 121, 122, 122, 123, 124, 125, 125, 126, 126, 126, 127, 127, 127,
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};
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sbyte isin(byte x0) {
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byte x = x0;
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if (x0 & 0x40) x = 127-x;
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if (x0 & 0x80) {
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return -sintbl[x+128];
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} else {
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return sintbl[x];
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}
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}
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sbyte icos(byte x) {
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return isin(x+64);
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}
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void mat_rotate(Matrix* m, byte axis, byte angle) {
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sbyte sin = isin(angle);
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sbyte cos = icos(angle);
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mat_identity(m);
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switch (axis) {
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case 0:
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m->m[1][1] = cos;
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m->m[2][1] = sin;
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m->m[1][2] = -sin;
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m->m[2][2] = cos;
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break;
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case 1:
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m->m[2][2] = cos;
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m->m[0][2] = sin;
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m->m[2][0] = -sin;
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m->m[0][0] = cos;
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break;
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case 2:
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m->m[0][0] = cos;
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m->m[1][0] = sin;
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m->m[0][1] = -sin;
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m->m[1][1] = cos;
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break;
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}
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}
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const Vector8 tetra_v[] = { {0,-86,86},{86,86,86},{-86,86,86},{0,0,-86} };
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const char tetra_e[] = { 0, 1, 2, 0, 3, 1, -1, 3, 2, -2 };
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const Wireframe tetra = { 4, tetra_v, tetra_e };
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void xform_vertices(Vector16* dest, const Vector8* src, const Matrix* m, byte nv) {
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byte i;
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for (i=0; i<nv; i++) {
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vec_mat_transform(dest++, src++, m);
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}
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}
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void draw_wireframe_ortho(const Wireframe* wf, const Matrix* m) {
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const char* e = wf->edges;
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byte bright = 0;
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int x1 = 0;
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int y1 = 0;
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Vector16 scrnverts[16];
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xform_vertices(scrnverts, wf->verts, m, wf->numverts);
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do {
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sbyte i = *e++;
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if (i == -1)
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bright = 0;
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else if (i == -2)
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break;
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else {
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int x2 = scrnverts[i].x>>8;
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int y2 = scrnverts[i].y>>8;
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VCTR(x2-x1, y2-y1, bright);
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x1 = x2;
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y1 = y2;
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}
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bright = 2;
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} while (1);
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}
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///
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word frame;
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void main() {
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int x,y;
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Matrix m;
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mat_identity(&m);
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while (1) {
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dvgreset();
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CNTR();
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SCAL(0x1f);
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STAT(RED, 5);
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x = isin(frame/8);
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y = icos(frame/8);
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VCTR(x, y, 2);
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STAT(GREEN, 15);
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mat_rotate(&m, (frame>>8)&3, frame);
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draw_wireframe_ortho(&tetra, &m);
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HALT();
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dvgstart();
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frame++;
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}
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}
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