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GLdc/gl-clip.c

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Normalize line endings in libgl to LF rather than CRLF.
2014-08-29 19:56:23 +00:00
/* KallistiGL for KallistiOS ##version##
libgl/gl-clip.c
Copyright (C) 2013-2014 Josh "PH3NOM" Pearson
Near-Z Clipping Algorithm (C) 2013-2014 Josh PH3NOM Pearson
Input Primitive Types Supported:
-GL_TRIANGLES
-GL_TRIANGLE_STRIPS
-GL_QUADS
Outputs a mix of Triangles and Triangle Strips for use with the PVR
*/
#include <stdio.h>
#include <string.h>
#include "gl-clip.h"
static float3 CLIP_BUF[1024 * 32];
static inline void glVertexCopy3f(float3 *src, float3 *dst) {
*dst = *src;
}
static inline void glVertexCopyPVR(pvr_vertex_t *src, pvr_vertex_t *dst) {
*dst = *src;
}
static inline void _glKosVertexCopyPVR(pvr_vertex_t *src, pvr_vertex_t *dst) {
*dst = *src;
}
static inline float ZclipMag(float3 *v1, float3 *v2) {
return ((CLIP_NEARZ - v1->z) / (v2->z - v1->z));
}
static inline void glVertexClipZNear(pvr_vertex_t *v1, pvr_vertex_t *v2, float MAG) {
colorui *c1 = (colorui *)&v1->argb;
colorui *c2 = (colorui *)&v2->argb;
v1->x += (v2->x - v1->x) * MAG;
v1->y += (v2->y - v1->y) * MAG;
v1->z += (v2->z - v1->z) * MAG;
v1->u += (v2->u - v1->u) * MAG;
v1->v += (v2->v - v1->v) * MAG;
c1->a += (c2->a - c1->a) * MAG;
c1->r += (c2->r - c1->r) * MAG;
c1->g += (c2->g - c1->g) * MAG;
c1->b += (c2->b - c1->b) * MAG;
}
static inline void _glKosVertexClipZNear3(pvr_vertex_t *v1, pvr_vertex_t *v2, float *w1, float *w2) {
float MAG = ((CLIP_NEARZ - v1->z) / (v2->z - v1->z));
colorui *c1 = (colorui *)&v1->argb;
colorui *c2 = (colorui *)&v2->argb;
v1->x += (v2->x - v1->x) * MAG;
v1->y += (v2->y - v1->y) * MAG;
v1->z += (v2->z - v1->z) * MAG;
v1->u += (v2->u - v1->u) * MAG;
v1->v += (v2->v - v1->v) * MAG;
c1->a += (c2->a - c1->a) * MAG;
c1->r += (c2->r - c1->r) * MAG;
c1->g += (c2->g - c1->g) * MAG;
c1->b += (c2->b - c1->b) * MAG;
*w1 += (*w2 - *w1) * MAG;
}
static GLuint glTransformClip(pvr_vertex_t *v, int count) {
pvr_vertex_t *V = v;
float3 *C = CLIP_BUF;
GLuint in = 0;
while(count--) {
mat_trans_single3_nodiv_nomod(V->x, V->y, V->z, C->x, C->y, C->z);
if(C->z < CLIP_NEARZ) ++in;
++C;
++V;
}
return in;
}
GLuint _glKosClipTriangleStrip(pvr_vertex_t *vin, pvr_vertex_t *vout, unsigned int vertices) {
GLuint i, v = 0, in = glTransformClip(vin, vertices);
float3 *C = CLIP_BUF;
if(in == vertices) {
memcpy(vout, vin, vertices * 0x20);
pvr_vertex_t *v = vout;
while(--in) {
v->flags = PVR_CMD_VERTEX;
++v;
}
v->flags = PVR_CMD_VERTEX_EOL;
return vertices;
}
else if(in == 0)
return 0;
/* Iterate all Triangles of the Strip - Hence looping vertices-2 times */
for(i = 0; i < ((vertices) - 2); i++) {
unsigned short int clip = 0; /* Clip Code for current Triangle */
unsigned char verts_in = 0; /* # of Verteices inside clip plane for current Triangle */
C->z >= CLIP_NEARZ ? clip |= FIRST : ++verts_in;
(C + 1)->z >= CLIP_NEARZ ? clip |= SECOND : ++verts_in;
(C + 2)->z >= CLIP_NEARZ ? clip |= THIRD : ++verts_in;
switch(verts_in) { /* Start by examining # of vertices inside clip plane */
case 0: /* All Vertices of Triangle are outside of clip plne */
break;
case 3: /* All Vertices of Triangle are inside of clip plne */
memcpy(&vout[v], &vin[i], 96);
vout[v].flags = vout[v + 1].flags = PVR_CMD_VERTEX;
vout[v + 2].flags = PVR_CMD_VERTEX_EOL;
v += 3;
break;
case 1:/* 1 Vertex of Triangle is inside of clip plane = output 1 Triangle */
memcpy(&vout[v], &vin[i], 96);
switch(clip) {
case FIRST_TWO_OUT:
glVertexClipZNear(&vout[v], &vout[v + 2], ZclipMag(&CLIP_BUF[i], &CLIP_BUF[i + 2]));
glVertexClipZNear(&vout[v + 1], &vout[v + 2], ZclipMag(&CLIP_BUF[i + 1], &CLIP_BUF[i + 2]));
break;
case FIRST_AND_LAST_OUT:
glVertexClipZNear(&vout[v], &vout[v + 1], ZclipMag(&CLIP_BUF[i], &CLIP_BUF[i + 1]));
glVertexClipZNear(&vout[v + 2], &vout[v + 1], ZclipMag(&CLIP_BUF[i + 2], &CLIP_BUF[i + 1]));
break;
case LAST_TWO_OUT:
glVertexClipZNear(&vout[v + 1], &vout[v], ZclipMag(&CLIP_BUF[i + 1], &CLIP_BUF[i + 0]));
glVertexClipZNear(&vout[v + 2], &vout[v], ZclipMag(&CLIP_BUF[i + 2], &CLIP_BUF[i + 0]));
break;
}
vout[v].flags = vout[v + 1].flags = PVR_CMD_VERTEX;
vout[v + 2].flags = PVR_CMD_VERTEX_EOL;
v += 3;
break;
case 2:/* 2 Vertices of Triangle are inside of clip plane = output 2 Triangles */
switch(clip) {
case FIRST:
glVertexCopyPVR(&vin[i + 0], &vout[v + 0]);
glVertexCopyPVR(&vin[i + 1], &vout[v + 1]);
glVertexCopyPVR(&vin[i + 0], &vout[v + 2]);
glVertexCopyPVR(&vin[i + 2], &vout[v + 3]);
glVertexClipZNear(&vout[v + 0], &vout[v + 1], ZclipMag(&CLIP_BUF[i], &CLIP_BUF[i + 1]));
glVertexClipZNear(&vout[v + 2], &vout[v + 3], ZclipMag(&CLIP_BUF[i], &CLIP_BUF[i + 2]));
break;
case SECOND:
glVertexCopyPVR(&vin[i + 1], &vout[v + 0]);
glVertexCopyPVR(&vin[i + 0], &vout[v + 1]);
glVertexCopyPVR(&vin[i + 1], &vout[v + 2]);
glVertexCopyPVR(&vin[i + 2], &vout[v + 3]);
glVertexClipZNear(&vout[v + 0], &vout[v + 1], ZclipMag(&CLIP_BUF[i + 1], &CLIP_BUF[i + 0]));
glVertexClipZNear(&vout[v + 2], &vout[v + 3], ZclipMag(&CLIP_BUF[i + 1], &CLIP_BUF[i + 2]));
break;
case THIRD:
glVertexCopyPVR(&vin[i + 2], &vout[v + 0]);
glVertexCopyPVR(&vin[i + 0], &vout[v + 1]);
glVertexCopyPVR(&vin[i + 2], &vout[v + 2]);
glVertexCopyPVR(&vin[i + 1], &vout[v + 3]);
glVertexClipZNear(&vout[v + 0], &vout[v + 1], ZclipMag(&CLIP_BUF[i + 2], &CLIP_BUF[i]));
glVertexClipZNear(&vout[v + 2], &vout[v + 3], ZclipMag(&CLIP_BUF[i + 2], &CLIP_BUF[i + 1]));
break;
}
vout[v + 0].flags = vout[v + 1].flags = vout[v + 2].flags = PVR_CMD_VERTEX;
vout[v + 3].flags = PVR_CMD_VERTEX_EOL;
v += 4;
break;
}
C++;
}
return v;
}
static inline unsigned char _glKosClipTri(pvr_vertex_t *vin, pvr_vertex_t *vout) {
unsigned short int clip = 0; /* Clip Code for current Triangle */
unsigned char verts_in = 0; /* # of Vertices inside clip plane for current Triangle */
float3 clip_buf[3]; /* Store the Vertices for each Triangle Translated into Clip Space */
/* Transform all 3 Vertices of Triangle */
{
register float __x __asm__("fr12") = vin->x;
register float __y __asm__("fr13") = vin->y;
register float __z __asm__("fr14") = vin->z;
mat_trans_fv12_nodiv();
clip_buf[0].x = __x;
clip_buf[0].y = __y;
clip_buf[0].z = __z;
__x = (vin + 1)->x;
__y = (vin + 1)->y;
__z = (vin + 1)->z;
mat_trans_fv12_nodiv();
clip_buf[1].x = __x;
clip_buf[1].y = __y;
clip_buf[1].z = __z;
__x = (vin + 2)->x;
__y = (vin + 2)->y;
__z = (vin + 2)->z;
mat_trans_fv12_nodiv();
clip_buf[2].x = __x;
clip_buf[2].y = __y;
clip_buf[2].z = __z;
/* Compute Clip Code for Triangle */
(clip_buf[0].z >= CLIP_NEARZ) ? clip |= FIRST : ++verts_in;
(clip_buf[1].z >= CLIP_NEARZ) ? clip |= SECOND : ++verts_in;
(clip_buf[2].z >= CLIP_NEARZ) ? clip |= THIRD : ++verts_in;
}
switch(verts_in) { /* Start by examining # of vertices inside clip plane */
case 0: /* All Vertices of Triangle are Outside of clip plne */
return 0;
case 3: /* All Vertices of Triangle are inside of clip plne */
memcpy(vout, vin, 96);
vout->flags = (vout + 1)->flags = PVR_CMD_VERTEX;
(vout + 2)->flags = PVR_CMD_VERTEX_EOL;
return 3;
case 1:/* 1 Vertex of Triangle is inside of clip plane = output 1 Triangle */
memcpy(vout, vin, 96);
switch(clip) {
case FIRST_TWO_OUT:
glVertexClipZNear(vout, vout + 2, ZclipMag(&clip_buf[0], &clip_buf[2]));
glVertexClipZNear(vout + 1, vout + 2, ZclipMag(&clip_buf[1], &clip_buf[2]));
break;
case FIRST_AND_LAST_OUT:
glVertexClipZNear(vout, vout + 1, ZclipMag(&clip_buf[0], &clip_buf[1]));
glVertexClipZNear(vout + 2, vout + 1, ZclipMag(&clip_buf[2], &clip_buf[1]));
break;
case LAST_TWO_OUT:
glVertexClipZNear(vout + 1, vout, ZclipMag(&clip_buf[1], &clip_buf[0]));
glVertexClipZNear(vout + 2, vout, ZclipMag(&clip_buf[2], &clip_buf[0]));
break;
}
vout->flags = (vout + 1)->flags = PVR_CMD_VERTEX;
(vout + 2)->flags = PVR_CMD_VERTEX_EOL;
return 3;
case 2:/* 2 Vertices of Triangle are inside of clip plane = output 2 Triangles */
switch(clip) {
case FIRST:
memcpy(vout, vin, 64);
glVertexCopyPVR(vin, vout + 2);
glVertexCopyPVR(vin + 2, vout + 3);
glVertexClipZNear(vout, vout + 1, ZclipMag(&clip_buf[0], &clip_buf[1]));
glVertexClipZNear(vout + 2, vout + 3, ZclipMag(&clip_buf[0], &clip_buf[2]));
break;
case SECOND:
glVertexCopyPVR(vin + 1, vout);
glVertexCopyPVR(vin, vout + 1);
memcpy(vout + 2, vin + 1, 64);
glVertexClipZNear(vout, vout + 1, ZclipMag(&clip_buf[1], &clip_buf[0]));
glVertexClipZNear(vout + 2, vout + 3, ZclipMag(&clip_buf[1], &clip_buf[2]));
break;
case THIRD:
glVertexCopyPVR(vin + 2, vout);
glVertexCopyPVR(vin, vout + 1);
glVertexCopyPVR(vin + 2, vout + 2);
glVertexCopyPVR(vin + 1, vout + 3);
glVertexClipZNear(vout, vout + 1, ZclipMag(&clip_buf[2], &clip_buf[0]));
glVertexClipZNear(vout + 2, vout + 3, ZclipMag(&clip_buf[2], &clip_buf[1]));
break;
}
vout->flags = (vout + 1)->flags = (vout + 2)->flags = PVR_CMD_VERTEX;
(vout + 3)->flags = PVR_CMD_VERTEX_EOL;
return 4;
}
return 0;
}
unsigned int _glKosClipTriangles(pvr_vertex_t *vin, pvr_vertex_t *vout, unsigned int vertices) {
unsigned int i, v = 0;
for(i = 0; i < vertices; i += 3) /* Iterate all Triangles */
v += _glKosClipTri(vin + i, vout + v);
return v;
}
unsigned int _glKosClipQuads(pvr_vertex_t *vin, pvr_vertex_t *vout, unsigned int vertices) {
unsigned int i, v = 0;
pvr_vertex_t qv;
for(i = 0; i < vertices; i += 4) { /* Iterate all Quads, Rearranging into Triangle Strips */
glVertexCopyPVR(vin + i + 3, &qv);
glVertexCopyPVR(vin + i + 2, vin + i + 3);
glVertexCopyPVR(&qv, vin + i + 2);
v += _glKosClipTriangleStrip(vin + i, vout + v, 4);
}
return v;
}
static inline void _glKosVertexPerspectiveDivide(pvr_vertex_t *dst, float w) {
dst->z = 1.0f / w;
dst->x *= dst->z;
dst->y *= dst->z;
}
GLuint _glKosClipTrianglesTransformed(pvr_vertex_t *src, float *w, pvr_vertex_t *dst, GLuint count) {
pvr_vertex_t *vin = src;
pvr_vertex_t *vout = dst;
unsigned short int clip;
unsigned char verts_in = 0;
GLuint verts_out = 0;
GLuint i;
for(i = 0; i < count; i += 3) {
clip = 0; /* Clip Code for current Triangle */
verts_in = 0; /* # of Vertices inside clip plane for current Triangle */
float W[4] = { w[i], w[i + 1], w[i + 2] }; /* W Component for Perspective Divide */
(vin[0].z >= CLIP_NEARZ) ? clip |= FIRST : ++verts_in;
(vin[1].z >= CLIP_NEARZ) ? clip |= SECOND : ++verts_in;
(vin[2].z >= CLIP_NEARZ) ? clip |= THIRD : ++verts_in;
switch(verts_in) { /* Start by examining # of vertices inside clip plane */
case 0: /* All Vertices of Triangle are Outside of clip plne */
break;
case 3: /* All Vertices of Triangle are inside of clip plne */
_glKosVertexCopyPVR(&vin[0], &vout[0]);
_glKosVertexCopyPVR(&vin[1], &vout[1]);
_glKosVertexCopyPVR(&vin[2], &vout[2]);
_glKosVertexPerspectiveDivide(&vout[0], W[0]);
_glKosVertexPerspectiveDivide(&vout[1], W[1]);
_glKosVertexPerspectiveDivide(&vout[2], W[2]);
vout[0].flags = vout[1].flags = PVR_CMD_VERTEX;
vout[2].flags = PVR_CMD_VERTEX_EOL;
vout += 3;
verts_out += 3;
break;
case 1:/* 1 Vertex of Triangle is inside of clip plane = output 1 Triangle */
_glKosVertexCopyPVR(&vin[0], &vout[0]);
_glKosVertexCopyPVR(&vin[1], &vout[1]);
_glKosVertexCopyPVR(&vin[2], &vout[2]);
switch(clip) {
case FIRST_TWO_OUT:
_glKosVertexClipZNear3(&vout[0], &vout[2], &W[0], &W[2]);
_glKosVertexClipZNear3(&vout[1], &vout[2], &W[1], &W[2]);
break;
case FIRST_AND_LAST_OUT:
_glKosVertexClipZNear3(&vout[0], &vout[1], &W[0], &W[1]);
_glKosVertexClipZNear3(&vout[2], &vout[1], &W[2], &W[1]);
break;
case LAST_TWO_OUT:
_glKosVertexClipZNear3(&vout[1], &vout[0], &W[1], &W[0]);
_glKosVertexClipZNear3(&vout[2], &vout[0], &W[2], &W[0]);
break;
}
_glKosVertexPerspectiveDivide(&vout[0], W[0]);
_glKosVertexPerspectiveDivide(&vout[1], W[1]);
_glKosVertexPerspectiveDivide(&vout[2], W[2]);
vout[0].flags = vout[1].flags = PVR_CMD_VERTEX;
vout[2].flags = PVR_CMD_VERTEX_EOL;
vout += 3;
verts_out += 3;
break;
case 2:/* 2 Vertices of Triangle are inside of clip plane = output 2 Triangles */
switch(clip) {
case FIRST:
_glKosVertexCopyPVR(&vin[0], &vout[0]);
_glKosVertexCopyPVR(&vin[1], &vout[1]);
_glKosVertexCopyPVR(&vin[0], &vout[2]);
_glKosVertexCopyPVR(&vin[2], &vout[3]);
W[3] = W[2];
W[2] = W[0];
break;
case SECOND:
_glKosVertexCopyPVR(&vin[1], &vout[0]);
_glKosVertexCopyPVR(&vin[2], &vout[1]);
_glKosVertexCopyPVR(&vin[1], &vout[2]);
_glKosVertexCopyPVR(&vin[0], &vout[3]);
W[3] = W[0];
W[0] = W[1];
W[1] = W[2];
W[2] = W[0];
break;
case THIRD:
_glKosVertexCopyPVR(&vin[2], &vout[0]);
_glKosVertexCopyPVR(&vin[0], &vout[1]);
_glKosVertexCopyPVR(&vin[2], &vout[2]);
_glKosVertexCopyPVR(&vin[1], &vout[3]);
W[3] = W[1];
W[1] = W[0];
W[0] = W[2];
break;
}
_glKosVertexClipZNear3(&vout[0], &vout[1], &W[0], &W[1]);
_glKosVertexClipZNear3(&vout[2], &vout[3], &W[2], &W[3]);
_glKosVertexPerspectiveDivide(&vout[0], W[0]);
_glKosVertexPerspectiveDivide(&vout[1], W[1]);
_glKosVertexPerspectiveDivide(&vout[2], W[2]);
_glKosVertexPerspectiveDivide(&vout[3], W[3]);
vout[0].flags = vout[1].flags = vout[2].flags = PVR_CMD_VERTEX;
vout[3].flags = PVR_CMD_VERTEX_EOL;
vout += 4;
verts_out += 4;
break;
}
vin += 3;
}
return verts_out;
}
GLuint _glKosClipTriangleStripTransformed(pvr_vertex_t *src, float *w, pvr_vertex_t *dst, GLuint count) {
pvr_vertex_t *vin = src;
pvr_vertex_t *vout = dst;
unsigned short int clip;
unsigned char verts_in = 0;
GLuint verts_out = 0;
GLuint i;
for(i = 0; i < (count - 2); i ++) {
clip = 0; /* Clip Code for current Triangle */
verts_in = 0; /* # of Vertices inside clip plane for current Triangle */
float W[4] = { w[i], w[i + 1], w[i + 2] }; /* W Component for Perspective Divide */
(vin[0].z >= CLIP_NEARZ) ? clip |= FIRST : ++verts_in;
(vin[1].z >= CLIP_NEARZ) ? clip |= SECOND : ++verts_in;
(vin[2].z >= CLIP_NEARZ) ? clip |= THIRD : ++verts_in;
switch(verts_in) { /* Start by examining # of vertices inside clip plane */
case 0: /* All Vertices of Triangle are Outside of clip plne */
break;
case 3: /* All Vertices of Triangle are inside of clip plne */
_glKosVertexCopyPVR(&vin[0], &vout[0]);
_glKosVertexCopyPVR(&vin[1], &vout[1]);
_glKosVertexCopyPVR(&vin[2], &vout[2]);
_glKosVertexPerspectiveDivide(&vout[0], W[0]);
_glKosVertexPerspectiveDivide(&vout[1], W[1]);
_glKosVertexPerspectiveDivide(&vout[2], W[2]);
vout[0].flags = vout[1].flags = PVR_CMD_VERTEX;
vout[2].flags = PVR_CMD_VERTEX_EOL;
vout += 3;
verts_out += 3;
break;
case 1:/* 1 Vertex of Triangle is inside of clip plane = output 1 Triangle */
_glKosVertexCopyPVR(&vin[0], &vout[0]);
_glKosVertexCopyPVR(&vin[1], &vout[1]);
_glKosVertexCopyPVR(&vin[2], &vout[2]);
switch(clip) {
case FIRST_TWO_OUT:
_glKosVertexClipZNear3(&vout[0], &vout[2], &W[0], &W[2]);
_glKosVertexClipZNear3(&vout[1], &vout[2], &W[1], &W[2]);
break;
case FIRST_AND_LAST_OUT:
_glKosVertexClipZNear3(&vout[0], &vout[1], &W[0], &W[1]);
_glKosVertexClipZNear3(&vout[2], &vout[1], &W[2], &W[1]);
break;
case LAST_TWO_OUT:
_glKosVertexClipZNear3(&vout[1], &vout[0], &W[1], &W[0]);
_glKosVertexClipZNear3(&vout[2], &vout[0], &W[2], &W[0]);
break;
}
_glKosVertexPerspectiveDivide(&vout[0], W[0]);
_glKosVertexPerspectiveDivide(&vout[1], W[1]);
_glKosVertexPerspectiveDivide(&vout[2], W[2]);
vout[0].flags = vout[1].flags = PVR_CMD_VERTEX;
vout[2].flags = PVR_CMD_VERTEX_EOL;
vout += 3;
verts_out += 3;
break;
case 2:/* 2 Vertices of Triangle are inside of clip plane = output 2 Triangles */
switch(clip) {
case FIRST:
_glKosVertexCopyPVR(&vin[0], &vout[0]);
_glKosVertexCopyPVR(&vin[1], &vout[1]);
_glKosVertexCopyPVR(&vin[0], &vout[2]);
_glKosVertexCopyPVR(&vin[2], &vout[3]);
W[3] = W[2];
W[2] = W[0];
break;
case SECOND:
_glKosVertexCopyPVR(&vin[1], &vout[0]);
_glKosVertexCopyPVR(&vin[2], &vout[1]);
_glKosVertexCopyPVR(&vin[1], &vout[2]);
_glKosVertexCopyPVR(&vin[0], &vout[3]);
W[3] = W[0];
W[0] = W[1];
W[1] = W[2];
W[2] = W[0];
break;
case THIRD:
_glKosVertexCopyPVR(&vin[2], &vout[0]);
_glKosVertexCopyPVR(&vin[0], &vout[1]);
_glKosVertexCopyPVR(&vin[2], &vout[2]);
_glKosVertexCopyPVR(&vin[1], &vout[3]);
W[3] = W[1];
W[1] = W[0];
W[0] = W[2];
break;
}
_glKosVertexClipZNear3(&vout[0], &vout[1], &W[0], &W[1]);
_glKosVertexClipZNear3(&vout[2], &vout[3], &W[2], &W[3]);
_glKosVertexPerspectiveDivide(&vout[0], W[0]);
_glKosVertexPerspectiveDivide(&vout[1], W[1]);
_glKosVertexPerspectiveDivide(&vout[2], W[2]);
_glKosVertexPerspectiveDivide(&vout[3], W[3]);
vout[0].flags = vout[1].flags = vout[2].flags = PVR_CMD_VERTEX;
vout[3].flags = PVR_CMD_VERTEX_EOL;
vout += 4;
verts_out += 4;
break;
}
++vin;
}
return verts_out;
}
GLubyte _glKosClipTriTransformed(pvr_vertex_t *vin, float *w, pvr_vertex_t *vout) {
unsigned short int clip = 0; /* Clip Code for current Triangle */
unsigned char verts_in = 0; /* # of Vertices inside clip plane for current Triangle */
float W[4] = { w[0], w[1], w[2] }; /* W Component for Perspective Divide */
(vin[0].z >= CLIP_NEARZ) ? clip |= FIRST : ++verts_in;
(vin[1].z >= CLIP_NEARZ) ? clip |= SECOND : ++verts_in;
(vin[2].z >= CLIP_NEARZ) ? clip |= THIRD : ++verts_in;
switch(verts_in) { /* Start by examining # of vertices inside clip plane */
case 0: /* All Vertices of Triangle are Outside of clip plne */
return 0;
case 3: /* All Vertices of Triangle are inside of clip plne */
_glKosVertexCopyPVR(&vin[0], &vout[0]);
_glKosVertexCopyPVR(&vin[1], &vout[1]);
_glKosVertexCopyPVR(&vin[2], &vout[2]);
_glKosVertexPerspectiveDivide(&vout[0], W[0]);
_glKosVertexPerspectiveDivide(&vout[1], W[1]);
_glKosVertexPerspectiveDivide(&vout[2], W[2]);
vout[0].flags = vout[1].flags = PVR_CMD_VERTEX;
vout[2].flags = PVR_CMD_VERTEX_EOL;
return 3;
case 1:/* 1 Vertex of Triangle is inside of clip plane = output 1 Triangle */
_glKosVertexCopyPVR(&vin[0], &vout[0]);
_glKosVertexCopyPVR(&vin[1], &vout[1]);
_glKosVertexCopyPVR(&vin[2], &vout[2]);
switch(clip) {
case FIRST_TWO_OUT:
_glKosVertexClipZNear3(&vout[0], &vout[2], &W[0], &W[2]);
_glKosVertexClipZNear3(&vout[1], &vout[2], &W[1], &W[2]);
break;
case FIRST_AND_LAST_OUT:
_glKosVertexClipZNear3(&vout[0], &vout[1], &W[0], &W[1]);
_glKosVertexClipZNear3(&vout[2], &vout[1], &W[2], &W[1]);
break;
case LAST_TWO_OUT:
_glKosVertexClipZNear3(&vout[1], &vout[0], &W[1], &W[0]);
_glKosVertexClipZNear3(&vout[2], &vout[0], &W[2], &W[0]);
break;
}
_glKosVertexPerspectiveDivide(&vout[0], W[0]);
_glKosVertexPerspectiveDivide(&vout[1], W[1]);
_glKosVertexPerspectiveDivide(&vout[2], W[2]);
vout[0].flags = vout[1].flags = PVR_CMD_VERTEX;
vout[2].flags = PVR_CMD_VERTEX_EOL;
return 3;
case 2:/* 2 Vertices of Triangle are inside of clip plane = output 2 Triangles */
switch(clip) {
case FIRST:
_glKosVertexCopyPVR(&vin[0], &vout[0]);
_glKosVertexCopyPVR(&vin[1], &vout[1]);
_glKosVertexCopyPVR(&vin[0], &vout[2]);
_glKosVertexCopyPVR(&vin[2], &vout[3]);
W[3] = W[2];
W[2] = W[0];
break;
case SECOND:
_glKosVertexCopyPVR(&vin[1], &vout[0]);
_glKosVertexCopyPVR(&vin[2], &vout[1]);
_glKosVertexCopyPVR(&vin[1], &vout[2]);
_glKosVertexCopyPVR(&vin[0], &vout[3]);
W[3] = W[0];
W[0] = W[1];
W[1] = W[2];
W[2] = W[0];
break;
case THIRD:
_glKosVertexCopyPVR(&vin[2], &vout[0]);
_glKosVertexCopyPVR(&vin[0], &vout[1]);
_glKosVertexCopyPVR(&vin[2], &vout[2]);
_glKosVertexCopyPVR(&vin[1], &vout[3]);
W[3] = W[1];
W[1] = W[0];
W[0] = W[2];
break;
}
_glKosVertexClipZNear3(&vout[0], &vout[1], &W[0], &W[1]);
_glKosVertexClipZNear3(&vout[2], &vout[3], &W[2], &W[3]);
_glKosVertexPerspectiveDivide(&vout[0], W[0]);
_glKosVertexPerspectiveDivide(&vout[1], W[1]);
_glKosVertexPerspectiveDivide(&vout[2], W[2]);
_glKosVertexPerspectiveDivide(&vout[3], W[3]);
vout[0].flags = vout[1].flags = vout[2].flags = PVR_CMD_VERTEX;
vout[3].flags = PVR_CMD_VERTEX_EOL;
return 4;
}
return 0;
}
unsigned int _glKosClipQuadsTransformed(pvr_vertex_t *vin, float *w, pvr_vertex_t *vout, unsigned int vertices) {
unsigned int i, v = 0;
pvr_vertex_t qv[3];
float W[3];
for(i = 0; i < vertices; i += 4) { /* Iterate all Quads, Rearranging into Triangle Strips */
_glKosVertexCopyPVR(&vin[i + 0], &qv[0]);
_glKosVertexCopyPVR(&vin[i + 2], &qv[1]);
_glKosVertexCopyPVR(&vin[i + 3], &qv[2]);
W[0] = w[0];
W[1] = w[2];
W[2] = w[3];
v += _glKosClipTriTransformed(&vin[i], &w[i], &vout[v]);
v += _glKosClipTriTransformed(&qv[i], &W[i], &vout[v]);
}
return v;
}
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