270 lines
7.3 KiB
C++
270 lines
7.3 KiB
C++
// Project64 - A Nintendo 64 emulator
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// http://www.pj64-emu.com/
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// Copyright(C) 2001-2021 Project64
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// Copyright(C) 2003-2009 Sergey 'Gonetz' Lipski
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// Copyright(C) 2002 Dave2001
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// GNU/GPLv2 licensed: https://gnu.org/licenses/gpl-2.0.html
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#include "Gfx_1.3.h"
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#include "rdp.h"
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#include "DepthBufferRender.h"
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uint16_t * zLUT = 0;
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void ZLUT_init()
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{
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if (zLUT)
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return;
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zLUT = new uint16_t[0x40000];
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for (int i = 0; i < 0x40000; i++)
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{
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uint32_t exponent = 0;
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uint32_t testbit = 1 << 17;
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while ((i & testbit) && (exponent < 7))
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{
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exponent++;
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testbit = 1 << (17 - exponent);
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}
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uint32_t mantissa = (i >> (6 - (6 < exponent ? 6 : exponent))) & 0x7ff;
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zLUT[i] = (uint16_t)(((exponent << 11) | mantissa) << 2);
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}
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}
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void ZLUT_release()
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{
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delete[] zLUT;
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zLUT = 0;
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}
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static vertexi * max_vtx; // Max y vertex (ending vertex)
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static vertexi * start_vtx, *end_vtx; // First and last vertex in array
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static vertexi * right_vtx, *left_vtx; // Current right and left vertex
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static int right_height, left_height;
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static int right_x, right_dxdy, left_x, left_dxdy;
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static int left_z, left_dzdy;
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__inline int imul16(int x, int y) // (x * y) >> 16
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{
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return ((int64_t)x * (int64_t)y) >> 16;
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}
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__inline int imul14(int x, int y) // (x * y) >> 14
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{
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return ((int64_t)x * (int64_t)y) >> 14;
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}
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__inline int idiv16(int x, int y) // (x << 16) / y
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{
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x = ((int64_t)x << 16) / (int64_t)y;
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return x;
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}
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__inline int iceil(int x)
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{
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x += 0xffff;
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return (x >> 16);
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}
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static void RightSection(void)
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{
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// Walk backwards trough the vertex array
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vertexi * v2, *v1 = right_vtx;
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if (right_vtx > start_vtx) v2 = right_vtx - 1;
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else v2 = end_vtx; // Wrap to end of array
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right_vtx = v2;
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// v1 = top vertex
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// v2 = bottom vertex
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// Calculate number of scanlines in this section
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right_height = iceil(v2->y) - iceil(v1->y);
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if (right_height <= 0) return;
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// Guard against possible div overflows
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if (right_height > 1) {
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// OK, no worries, we have a section that is at least
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// one pixel high. Calculate slope as usual.
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int height = v2->y - v1->y;
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right_dxdy = idiv16(v2->x - v1->x, height);
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}
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else {
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// Height is less or equal to one pixel.
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// Calculate slope = width * 1/height
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// using 18:14 bit precision to avoid overflows.
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int inv_height = (0x10000 << 14) / (v2->y - v1->y);
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right_dxdy = imul14(v2->x - v1->x, inv_height);
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}
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// Prestep initial values
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int prestep = (iceil(v1->y) << 16) - v1->y;
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right_x = v1->x + imul16(prestep, right_dxdy);
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}
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static void LeftSection(void)
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{
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// Walk forward trough the vertex array
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vertexi * v2, *v1 = left_vtx;
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if (left_vtx < end_vtx) v2 = left_vtx + 1;
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else v2 = start_vtx; // Wrap to start of array
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left_vtx = v2;
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// v1 = top vertex
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// v2 = bottom vertex
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// Calculate number of scanlines in this section
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left_height = iceil(v2->y) - iceil(v1->y);
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if (left_height <= 0) return;
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// Guard against possible div overflows
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if (left_height > 1) {
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// OK, no worries, we have a section that is at least
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// one pixel high. Calculate slope as usual.
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int height = v2->y - v1->y;
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left_dxdy = idiv16(v2->x - v1->x, height);
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left_dzdy = idiv16(v2->z - v1->z, height);
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}
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else {
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// Height is less or equal to one pixel.
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// Calculate slope = width * 1/height
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// using 18:14 bit precision to avoid overflows.
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int inv_height = (0x10000 << 14) / (v2->y - v1->y);
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left_dxdy = imul14(v2->x - v1->x, inv_height);
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left_dzdy = imul14(v2->z - v1->z, inv_height);
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}
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// Prestep initial values
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int prestep = (iceil(v1->y) << 16) - v1->y;
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left_x = v1->x + imul16(prestep, left_dxdy);
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left_z = v1->z + imul16(prestep, left_dzdy);
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}
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void Rasterize(vertexi * vtx, int vertices, int dzdx)
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{
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start_vtx = vtx; // First vertex in array
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// Search trough the vtx array to find min y, max y
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// and the location of these structures.
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vertexi * min_vtx = vtx;
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max_vtx = vtx;
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int min_y = vtx->y;
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int max_y = vtx->y;
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vtx++;
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for (int n = 1; n < vertices; n++) {
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if (vtx->y < min_y) {
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min_y = vtx->y;
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min_vtx = vtx;
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}
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else
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if (vtx->y > max_y) {
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max_y = vtx->y;
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max_vtx = vtx;
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}
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vtx++;
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}
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// OK, now we know where in the array we should start and
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// where to end while scanning the edges of the polygon
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left_vtx = min_vtx; // Left side starting vertex
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right_vtx = min_vtx; // Right side starting vertex
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end_vtx = vtx - 1; // Last vertex in array
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// Search for the first usable right section
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do {
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if (right_vtx == max_vtx) return;
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RightSection();
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} while (right_height <= 0);
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// Search for the first usable left section
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do {
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if (left_vtx == max_vtx) return;
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LeftSection();
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} while (left_height <= 0);
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uint16_t * destptr = (uint16_t*)(gfx.RDRAM + rdp.zimg);
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int y1 = iceil(min_y);
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if (y1 >= (int)rdp.scissor_o.lr_y) return;
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int shift;
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for (;;)
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{
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int x1 = iceil(left_x);
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if (x1 < (int)rdp.scissor_o.ul_x)
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x1 = rdp.scissor_o.ul_x;
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int width = iceil(right_x) - x1;
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if (x1 + width >= (int)rdp.scissor_o.lr_x)
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width = rdp.scissor_o.lr_x - x1 - 1;
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if (width > 0 && y1 >= (int)rdp.scissor_o.ul_y) {
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// Prestep initial z
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int prestep = (x1 << 16) - left_x;
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int z = left_z + imul16(prestep, dzdx);
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shift = x1 + y1*rdp.zi_width;
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//draw to depth buffer
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int trueZ;
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int idx;
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uint16_t encodedZ;
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for (int x = 0; x < width; x++)
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{
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trueZ = z / 8192;
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if (trueZ < 0) trueZ = 0;
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else if (trueZ > 0x3FFFF) trueZ = 0x3FFFF;
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encodedZ = zLUT[trueZ];
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idx = (shift + x) ^ 1;
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if (encodedZ < destptr[idx])
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destptr[idx] = encodedZ;
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z += dzdx;
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}
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}
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//destptr += rdp.zi_width;
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y1++;
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if (y1 >= (int)rdp.scissor_o.lr_y) return;
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// Scan the right side
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if (--right_height <= 0) { // End of this section?
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do {
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if (right_vtx == max_vtx) return;
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RightSection();
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} while (right_height <= 0);
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}
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else
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right_x += right_dxdy;
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// Scan the left side
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if (--left_height <= 0) { // End of this section?
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do {
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if (left_vtx == max_vtx) return;
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LeftSection();
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} while (left_height <= 0);
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}
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else {
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left_x += left_dxdy;
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left_z += left_dzdy;
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}
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}
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}
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