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GLdc/GL/clip.c
Luke Benstead da97483eee Switch to using 4-byte colours internally rather than floats 
These are stored in BGRA format so they can be directly cast to a uint32_t to get the
correct format for the argb param in pvr_vertex_t (yay endianess)

This results in a performance improvement as it reduces the data requirements.
2018-08-20 09:28:30 +01:00

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C
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#include <float.h>
#include <stdio.h>
#ifdef _arch_dreamcast
#include <dc/pvr.h>
#else
#define PVR_PACK_COLOR(a, r, g, b) {}
#endif
#include "profiler.h"
#include "clip.h"
#include "../containers/aligned_vector.h"
static unsigned char ZCLIP_ENABLED = 1;
unsigned char isClippingEnabled() {
return ZCLIP_ENABLED;
}
void enableClipping(unsigned char v) {
ZCLIP_ENABLED = v;
}
void clipLineToNearZ(const ClipVertex* v1, const ClipVertex* v2, ClipVertex* vout, float* t) __attribute__((optimize("fast-math")));
void clipLineToNearZ(const ClipVertex* v1, const ClipVertex* v2, ClipVertex* vout, float* t) {
const float NEAR_PLANE = 0.2; // FIXME: this needs to be read from the projection matrix.. somehow
*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;
void clipTriangleStrip(AlignedVector* vertices, AlignedVector* outBuffer) __attribute__((optimize("fast-math")));
void clipTriangleStrip(AlignedVector* vertices, AlignedVector* outBuffer) {
/* Clipping triangle strips is *hard* this is the algorithm we follow:
*
* - Treat each triangle in the strip individually.
* - If we find a triangle that needs clipping, treat it in isolation.
* - End the strip at the triangle
* - Generate a new single-triangle strip for it
* - Begin a new strip for the remainder of the strip
*
* There is probably more efficient way but there are so many different cases to handle that it's
* difficult to even write them down!
*/
uint32_t i;
uint32_t stripCount = 2; /* The number of vertices in the source strip so far */
ClipVertex* thisVertex = aligned_vector_at(vertices, 1);
for(i = 2; i < vertices->size; ++i) {
++thisVertex;
if(stripCount < 2) {
stripCount++;
continue;
}
const ClipVertex* sourceTriangle[3] = {
thisVertex - 2,
thisVertex - 1,
thisVertex
};
/* If we're on an odd vertex, we need to swap the order of the first two vertices, as that's what
* triangle strips do */
uint32_t swap = stripCount > 2 && (stripCount % 2 != 0);
const ClipVertex* v1 = swap ? sourceTriangle[1] : sourceTriangle[0];
const ClipVertex* v2 = swap ? sourceTriangle[0] : sourceTriangle[1];
const ClipVertex* v3 = sourceTriangle[2];
uint32_t visible = ((v1->w > 0) ? 4 : 0) | ((v2->w > 0) ? 2 : 0) | ((v3->w > 0) ? 1 : 0);
uint32_t startOfStrip = (i == 2) || (outBuffer->size > 2 && ((ClipVertex*) aligned_vector_back(outBuffer))->flags == VERTEX_CMD_EOL);
/* All visible, we're fine! */
if(visible == 0b111) {
if(startOfStrip) {
aligned_vector_push_back(outBuffer, v1, 1);
aligned_vector_push_back(outBuffer, v2, 1);
}
aligned_vector_push_back(outBuffer, v3, 1);
} else if(visible == 0b000) {
/* Do nothing */
continue;
} else if(visible == 0b100) {
/* Only the first vertex is visible */
float t1 = 0, t2 = 0;
ClipVertex output[3];
clipLineToNearZ(v1, v2, &output[1], &t1);
clipLineToNearZ(v1, v3, &output[2], &t2);
interpolateFloat(v1->w, v2->w, t1, &output[1].w);
interpolateFloat(v1->w, v3->w, t2, &output[2].w);
output[0] = *v1;
/* Interpolate normals */
interpolateVec3(v1->nxyz, v2->nxyz, t1, output[1].nxyz);
interpolateVec3(v1->nxyz, v3->nxyz, t2, output[2].nxyz);
/* Interpolate texcoords */
interpolateVec2(v1->uv, v2->uv, t1, output[1].uv);
interpolateVec2(v1->uv, v3->uv, t2, output[2].uv);
interpolateVec2(v1->st, v2->st, t1, output[1].st);
interpolateVec2(v1->st, v3->st, t2, output[2].st);
interpolateColour(v1->bgra, v2->bgra, t1, output[1].bgra);
interpolateColour(v1->bgra, v3->bgra, t2, output[2].bgra);
output[0].flags = VERTEX_CMD;
output[1].flags = VERTEX_CMD;
output[2].flags = VERTEX_CMD_EOL;
aligned_vector_push_back(outBuffer, output, 3);
} else if(visible == 0b010) {
/* Only the second vertex is visible */
float t1 = 0, t2 = 0;
ClipVertex output[3];
clipLineToNearZ(v2, v1, &output[0], &t1);
clipLineToNearZ(v2, v3, &output[2], &t2);
interpolateFloat(v2->w, v1->w, t1, &output[0].w);
interpolateFloat(v2->w, v3->w, t2, &output[2].w);
output[1] = *v2;
/* Interpolate normals */
interpolateVec3(v2->nxyz, v1->nxyz, t1, output[0].nxyz);
interpolateVec3(v2->nxyz, v3->nxyz, t2, output[2].nxyz);
/* Interpolate texcoords */
interpolateVec2(v2->uv, v1->uv, t1, output[0].uv);
interpolateVec2(v2->uv, v3->uv, t2, output[2].uv);
interpolateVec2(v2->st, v1->st, t1, output[0].st);
interpolateVec2(v2->st, v3->st, t2, output[2].st);
interpolateColour(v2->bgra, v1->bgra, t1, output[0].bgra);
interpolateColour(v2->bgra, v3->bgra, t2, output[2].bgra);
output[0].flags = VERTEX_CMD;
output[1].flags = VERTEX_CMD;
output[2].flags = VERTEX_CMD_EOL;
aligned_vector_push_back(outBuffer, output, 3);
} else if(visible == 0b001) {
/* Only the third vertex is visible */
float t1 = 0, t2 = 0;
ClipVertex output[3];
clipLineToNearZ(v3, v1, &output[0], &t1);
clipLineToNearZ(v3, v2, &output[1], &t2);
interpolateFloat(v3->w, v1->w, t1, &output[0].w);
interpolateFloat(v3->w, v2->w, t2, &output[1].w);
output[2] = *v3;
/* Interpolate normals */
interpolateVec3(v3->nxyz, v1->nxyz, t1, output[0].nxyz);
interpolateVec3(v3->nxyz, v2->nxyz, t2, output[1].nxyz);
/* Interpolate texcoords */
interpolateVec2(v3->uv, v1->uv, t1, output[0].uv);
interpolateVec2(v3->uv, v2->uv, t2, output[1].uv);
interpolateVec2(v3->st, v1->st, t1, output[0].st);
interpolateVec2(v3->st, v2->st, t2, output[1].st);
interpolateColour(v3->bgra, v1->bgra, t1, output[0].bgra);
interpolateColour(v3->bgra, v2->bgra, t2, output[1].bgra);
output[0].flags = VERTEX_CMD;
output[1].flags = VERTEX_CMD;
output[2].flags = VERTEX_CMD_EOL;
aligned_vector_push_back(outBuffer, output, 3);
} else if(visible == 0b110) {
/* Third vertex isn't visible */
float t1 = 0, t2 = 0;
ClipVertex output[4];
clipLineToNearZ(v2, v3, &output[2], &t1);
clipLineToNearZ(v1, v3, &output[3], &t2);
interpolateFloat(v2->w, v3->w, t1, &output[2].w);
interpolateFloat(v1->w, v3->w, t2, &output[3].w);
output[0] = *v1;
output[1] = *v2;
/* Interpolate normals */
interpolateVec3(v2->nxyz, v3->nxyz, t1, output[2].nxyz);
interpolateVec3(v1->nxyz, v3->nxyz, t2, output[3].nxyz);
/* Interpolate texcoords */
interpolateVec2(v2->uv, v3->uv, t1, output[2].uv);
interpolateVec2(v1->uv, v3->uv, t2, output[3].uv);
interpolateVec2(v2->st, v3->st, t1, output[2].st);
interpolateVec2(v1->st, v3->st, t2, output[3].st);
interpolateColour(v2->bgra, v3->bgra, t1, output[2].bgra);
interpolateColour(v1->bgra, v3->bgra, t2, output[3].bgra);
output[0].flags = VERTEX_CMD;
output[1].flags = VERTEX_CMD;
output[2].flags = VERTEX_CMD;
output[3].flags = VERTEX_CMD_EOL;
aligned_vector_push_back(outBuffer, output, 4);
} else if(visible == 0b011) {
/* First vertex isn't visible, so let's clip along the lines to the second and third */
float t1 = 0, t2 = 0;
ClipVertex output[4];
clipLineToNearZ(v1, v2, &output[0], &t1);
clipLineToNearZ(v1, v3, &output[2], &t2);
interpolateFloat(v1->w, v2->w, t1, &output[0].w);
interpolateFloat(v1->w, v3->w, t2, &output[2].w);
output[1] = *v2;
output[3] = *v3;
/* Interpolate normals */
interpolateVec3(v1->nxyz, v2->nxyz, t1, output[0].nxyz);
interpolateVec3(v1->nxyz, v3->nxyz, t2, output[2].nxyz);
/* Interpolate texcoords */
interpolateVec2(v1->uv, v2->uv, t1, output[0].uv);
interpolateVec2(v1->uv, v3->uv, t2, output[2].uv);
interpolateVec2(v1->st, v2->st, t1, output[0].st);
interpolateVec2(v1->st, v3->st, t2, output[2].st);
interpolateColour(v1->bgra, v2->bgra, t1, output[0].bgra);
interpolateColour(v1->bgra, v3->bgra, t2, output[2].bgra);
output[0].flags = VERTEX_CMD;
output[1].flags = VERTEX_CMD;
output[2].flags = VERTEX_CMD;
output[3].flags = VERTEX_CMD_EOL;
aligned_vector_push_back(outBuffer, output, 4);
} else if(visible == 0b101) {
/* Second vertex isn't visible */
float t1 = 0, t2 = 0;
ClipVertex output[4];
clipLineToNearZ(v1, v2, &output[1], &t1);
clipLineToNearZ(v3, v2, &output[3], &t2);
interpolateFloat(v1->w, v2->w, t1, &output[1].w);
interpolateFloat(v3->w, v2->w, t2, &output[3].w);
output[0] = *v1;
output[2] = *v3;
/* Interpolate normals */
interpolateVec3(v1->nxyz, v2->nxyz, t1, output[1].nxyz);
interpolateVec3(v3->nxyz, v2->nxyz, t2, output[3].nxyz);
/* Interpolate texcoords */
interpolateVec2(v1->uv, v2->uv, t1, output[1].uv);
interpolateVec2(v3->uv, v2->uv, t2, output[3].uv);
interpolateVec2(v1->st, v2->st, t1, output[1].st);
interpolateVec2(v3->st, v2->st, t2, output[3].st);
interpolateColour(v1->bgra, v2->bgra, t1, output[1].bgra);
interpolateColour(v3->bgra, v2->bgra, t2, output[3].bgra);
output[0].flags = VERTEX_CMD;
output[1].flags = VERTEX_CMD;
output[2].flags = VERTEX_CMD;
output[3].flags = VERTEX_CMD_EOL;
aligned_vector_push_back(outBuffer, output, 4);
}
/* If this vertex was the last in the list, reset the stripCount */
if(thisVertex->flags == VERTEX_CMD_EOL) {
stripCount = 0;
} else {
stripCount++;
}
}
}
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