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GLdc/GL/clip.c
Luke Benstead e39632bcc4 Refactor matrix management and clipping
2019-09-14 20:51:47 +01:00

386 lines
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#include <float.h>
#include <stdio.h>
#include <assert.h>
#include <string.h>
#ifdef _arch_dreamcast
#include <dc/pvr.h>
#else
#define PVR_PACK_COLOR(a, r, g, b) {}
#endif
#include "profiler.h"
#include "private.h"
#include "../containers/aligned_vector.h"
static unsigned char ZCLIP_ENABLED = 1;
unsigned char _glIsClippingEnabled() {
return ZCLIP_ENABLED;
}
void _glEnableClipping(unsigned char v) {
ZCLIP_ENABLED = v;
}
void _glClipLineToNearZ(const Vertex* v1, const Vertex* v2, Vertex* vout, float* t) __attribute__((optimize("fast-math")));
void _glClipLineToNearZ(const Vertex* v1, const Vertex* v2, Vertex* vout, float* t) {
const float NEAR_PLANE = NEAR_PLANE_DISTANCE + 0.0001f;
*t = (NEAR_PLANE - v1->w) / (v2->w - v1->w);
float vec [] = {v2->xyz[0] - v1->xyz[0], v2->xyz[1] - v1->xyz[1], v2->xyz[2] - v1->xyz[2]};
vout->xyz[0] = v1->xyz[0] + (vec[0] * (*t));
vout->xyz[1] = v1->xyz[1] + (vec[1] * (*t));
vout->xyz[2] = v1->xyz[2] + (vec[2] * (*t));
}
static inline void interpolateFloat(const float v1, const float v2, const float t, float* out) {
float v = v2 - v1;
*out = (v * t) + v1;
}
static inline void interpolateVec2(const float* v1, const float* v2, const float t, float* out) {
/* FIXME: SH4 has an asm instruction for this */
interpolateFloat(v1[0], v2[0], t, &out[0]);
interpolateFloat(v1[1], v2[1], t, &out[1]);
}
static inline void interpolateVec3(const float* v1, const float* v2, const float t, float* out) {
/* FIXME: SH4 has an asm instruction for this */
interpolateFloat(v1[0], v2[0], t, &out[0]);
interpolateFloat(v1[1], v2[1], t, &out[1]);
interpolateFloat(v1[2], v2[2], t, &out[2]);
}
static inline void interpolateVec4(const float* v1, const float* v2, const float t, float* out) {
/* FIXME: SH4 has an asm instruction for this */
interpolateFloat(v1[0], v2[0], t, &out[0]);
interpolateFloat(v1[1], v2[1], t, &out[1]);
interpolateFloat(v1[2], v2[2], t, &out[2]);
interpolateFloat(v1[3], v2[3], t, &out[3]);
}
static inline void interpolateColour(const uint8_t* v1, const uint8_t* v2, const float t, uint8_t* out) {
out[0] = v1[0] + (uint32_t) (((float) (v2[0] - v1[0])) * t);
out[1] = v1[1] + (uint32_t) (((float) (v2[1] - v1[1])) * t);
out[2] = v1[2] + (uint32_t) (((float) (v2[2] - v1[2])) * t);
out[3] = v1[3] + (uint32_t) (((float) (v2[3] - v1[3])) * t);
}
const uint32_t VERTEX_CMD_EOL = 0xf0000000;
const uint32_t VERTEX_CMD = 0xe0000000;
typedef struct {
Vertex vertex[3];
VertexExtra extra[3];
uint8_t visible;
} Triangle;
void _glClipTriangle(const Triangle* triangle, const uint8_t visible, SubmissionTarget* target, const uint8_t flatShade) __attribute__((optimize("fast-math")));
void _glClipTriangle(const Triangle* triangle, const uint8_t visible, SubmissionTarget* target, const uint8_t flatShade) {
uint8_t i, c = 0;
uint8_t lastVisible = 255;
Vertex* last = NULL;
VertexExtra* veLast = NULL;
const Vertex* vertices = triangle->vertex;
const VertexExtra* extras = triangle->extra;
/* Used when flat shading is enabled */
uint32_t finalColour = *((uint32_t*) vertices[2].bgra);
for(i = 0; i < 4; ++i) {
uint8_t thisIndex = (i == 3) ? 0 : i;
Vertex next;
VertexExtra veNext;
next.flags = VERTEX_CMD;
uint8_t thisVisible = (visible & (1 << (2 - thisIndex))) > 0;
if(i > 0) {
uint8_t lastIndex = (i == 3) ? 2 : thisIndex - 1;
if(lastVisible < 255 && lastVisible != thisVisible) {
const Vertex* v1 = &vertices[lastIndex];
const Vertex* v2 = &vertices[thisIndex];
const VertexExtra* ve1 = &extras[lastIndex];
const VertexExtra* ve2 = &extras[thisIndex];
float t;
_glClipLineToNearZ(v1, v2, &next, &t);
interpolateFloat(v1->w, v2->w, t, &next.w);
interpolateVec2(v1->uv, v2->uv, t, next.uv);
interpolateVec3(ve1->nxyz, ve2->nxyz, t, veNext.nxyz);
interpolateVec2(ve1->st, ve2->st, t, veNext.st);
if(flatShade) {
*((uint32_t*) next.bgra) = finalColour;
} else {
interpolateColour(v1->bgra, v2->bgra, t, next.bgra);
}
/* Push back the new vertices to the end of both the ClipVertex and VertexExtra lists */
last = aligned_vector_push_back(&target->output->vector, &next, 1);
last->flags = VERTEX_CMD;
veLast = aligned_vector_push_back(target->extras, &veNext, 1);
++c;
}
}
if(thisVisible && i != 3) {
last = aligned_vector_push_back(&target->output->vector, &vertices[thisIndex], 1);
last->flags = VERTEX_CMD;
veLast = aligned_vector_push_back(target->extras, &extras[thisIndex], 1);
++c;
}
lastVisible = thisVisible;
}
if(last) {
if(c == 4) {
/* Convert to two triangles */
Vertex newVerts[3];
newVerts[0] = *(last - 3);
newVerts[1] = *(last - 1);
newVerts[2] = *(last);
VertexExtra newExtras[3];
newExtras[0] = *(veLast - 3);
newExtras[1] = *(veLast - 1);
newExtras[2] = *(veLast);
(last - 1)->flags = VERTEX_CMD_EOL;
newVerts[0].flags = VERTEX_CMD;
newVerts[1].flags = VERTEX_CMD;
newVerts[2].flags = VERTEX_CMD_EOL;
aligned_vector_resize(&target->output->vector, target->output->vector.size - 1);
aligned_vector_push_back(&target->output->vector, newVerts, 3);
aligned_vector_resize(target->extras, target->extras->size - 1);
aligned_vector_push_back(target->extras, newExtras, 3);
} else {
last->flags = VERTEX_CMD_EOL;
}
}
}
static inline void markDead(Vertex* vert) {
vert->flags = VERTEX_CMD_EOL;
// If we're debugging, wipe out the xyz
#ifndef NDEBUG
*((uint32_t*) &vert->xyz[0]) = 0xDEADBEEF;
*((uint32_t*) &vert->xyz[1]) = 0xDEADBEEF;
*((uint32_t*) &vert->xyz[2]) = 0xDEADBEEF;
#endif
}
#define B000 0
#define B111 7
#define B100 4
#define B010 2
#define B001 1
#define B101 5
#define B011 3
#define B110 6
#define MAX_CLIP_TRIANGLES 255
void _glClipTriangleStrip(SubmissionTarget* target, uint8_t fladeShade) {
static Triangle TO_CLIP[MAX_CLIP_TRIANGLES];
static uint8_t CLIP_COUNT = 0;
CLIP_COUNT = 0;
Vertex* vertex = _glSubmissionTargetStart(target);
const Vertex* end = _glSubmissionTargetEnd(target);
const Vertex* start = vertex;
int32_t triangle = -1;
/* Go to the (potential) end of the first triangle */
vertex++;
uint32_t vi1, vi2, vi3;
while(vertex < end) {
vertex++;
triangle++;
uint8_t even = (triangle % 2) == 0;
Vertex* v1 = (even) ? vertex - 2 : vertex - 1;
Vertex* v2 = (even) ? vertex - 1 : vertex - 2;
Vertex* v3 = vertex;
/* Skip ahead if we don't have a complete triangle yet */
if(v1->flags != VERTEX_CMD || v2->flags != VERTEX_CMD) {
triangle = -1;
continue;
}
/* Indexes into extras array */
vi1 = v1 - start;
vi2 = v2 - start;
vi3 = v3 - start;
uint8_t visible = ((v1->w > 0) ? 4 : 0) | ((v2->w > 0) ? 2 : 0) | ((v3->w > 0) ? 1 : 0);
switch(visible) {
case B111:
/* All visible? Do nothing */
continue;
break;
case B000:
/*
It is not possible that this is any trangle except the first
in a strip. That's because:
- It's either the first triangle submitted
- A previous triangle must have been clipped and the strip
restarted behind the plane
So, we effectively reboot the strip. We mark the first vertex
as the end (so it's ignored) then mark the next two as the
start of a new strip. Then if the next triangle crosses
back into view, we clip correctly. This will potentially
result in a bunch of pointlessly submitted vertices.
FIXME: Skip submitting those verts
*/
/* Even though this is always the first in the strip, it can also
* be the last */
if(v3->flags == VERTEX_CMD_EOL) {
/* Wipe out the triangle */
markDead(v1);
markDead(v2);
markDead(v3);
} else {
markDead(v1);
swapVertex(v2, v3);
triangle = -1;
v2->flags = VERTEX_CMD;
v3->flags = VERTEX_CMD;
}
break;
case B100:
case B010:
case B001:
case B101:
case B011:
case B110:
assert(CLIP_COUNT < MAX_CLIP_TRIANGLES);
/* Store the triangle for clipping */
TO_CLIP[CLIP_COUNT].vertex[0] = *v1;
TO_CLIP[CLIP_COUNT].vertex[1] = *v2;
TO_CLIP[CLIP_COUNT].vertex[2] = *v3;
VertexExtra* ve1 = (VertexExtra*) aligned_vector_at(target->extras, vi1);
VertexExtra* ve2 = (VertexExtra*) aligned_vector_at(target->extras, vi2);
VertexExtra* ve3 = (VertexExtra*) aligned_vector_at(target->extras, vi3);
TO_CLIP[CLIP_COUNT].extra[0] = *ve1;
TO_CLIP[CLIP_COUNT].extra[1] = *ve2;
TO_CLIP[CLIP_COUNT].extra[2] = *ve3;
TO_CLIP[CLIP_COUNT].visible = visible;
++CLIP_COUNT;
/*
OK so here's the clever bit. If any triangle except
the first or last needs clipping, then the next one does aswell
(you can't draw a plane through a single triangle in the middle of a
strip, only 2+). This means we can clip in pairs which frees up two
vertices in the middle of the strip, which is exactly the space
we need to restart the triangle strip after the next triangle
*/
if(v3->flags == VERTEX_CMD_EOL) {
/* Last triangle in strip so end a vertex early */
if(triangle == 0) {
// Wipe out the triangle completely
markDead(v1);
markDead(v2);
} else {
// End the strip
(vertex - 1)->flags = VERTEX_CMD_EOL;
}
markDead(vertex);
triangle = -1;
} else if(triangle == 0) {
/* First triangle in strip, remove first vertex */
markDead(v1);
v2->flags = VERTEX_CMD;
v3->flags = VERTEX_CMD;
triangle = -1;
} else {
Vertex* v4 = v3 + 1;
uint32_t vi4 = v4 - start;
TO_CLIP[CLIP_COUNT].vertex[0] = *v3;
TO_CLIP[CLIP_COUNT].vertex[1] = *v2;
TO_CLIP[CLIP_COUNT].vertex[2] = *v4;
VertexExtra* ve4 = (VertexExtra*) aligned_vector_at(target->extras, vi4);
TO_CLIP[CLIP_COUNT].extra[0] = *(VertexExtra*) aligned_vector_at(target->extras, vi3);
TO_CLIP[CLIP_COUNT].extra[1] = *(VertexExtra*) aligned_vector_at(target->extras, vi2);
TO_CLIP[CLIP_COUNT].extra[2] = *ve4;
visible = ((v3->w > 0) ? 4 : 0) | ((v2->w > 0) ? 2 : 0) | ((v4->w > 0) ? 1 : 0);
TO_CLIP[CLIP_COUNT].visible = visible;
++CLIP_COUNT;
// Restart strip
triangle = -1;
// Mark the second vertex as the end of the strip
(vertex - 1)->flags = VERTEX_CMD_EOL;
if(v4->flags == VERTEX_CMD_EOL) {
markDead(v3);
markDead(v4);
} else {
// Swap the next vertices to start a new strip
swapVertex(v3, v4);
v3->flags = VERTEX_CMD;
v4->flags = VERTEX_CMD;
/* Swap the extra data too */
VertexExtra t = *ve4;
*ve3 = *ve4;
*ve4 = t;
}
}
break;
default:
break;
}
}
/* Now, clip all the triangles and append them to the output */
GLushort i;
for(i = 0; i < CLIP_COUNT; ++i) {
_glClipTriangle(&TO_CLIP[i], TO_CLIP[i].visible, target, fladeShade);
}
}
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