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/**
* @file z_viszbuf.c
*
* This file implements a full-screen framebuffer effect for visualizing the z-buffer (AKA depth buffer), using either
* cycling RGBA or a single fading color.
*
* This is done by reading the z-buffer as if it were a color image, the format of which is specified by the selected
* vis type:
* - VIS_ZBUF_TYPE_IA : Produces a monotonic fade from primColor to envColor as depth increases.
* - VIS_ZBUF_TYPE_RGBA : Produces vibrant almost-periodic-looking bands.
*
* In both cases this occurs because of the format the depth information takes: it is 18-bit, and is a nonnegative
* floating-point number with
* bbb mmmmmmmmmmm dd|dd
* exponent mantissa dz value (only first 16 bits visible to CPU, the least significant 2 bits of dz are ignored)
*
* Reading z-buffer as IA16:
* bbbmmmmm mmmmmmdd
* iiiiiiii aaaaaaaa
*
* Since floating-point numbers of this format have the same ordering as their binary/hex representation, increasing
* the depth also increases the intensity in the IA16 representation and hence the interpolation parameter used to
* combine primColor and envColor. The alpha is ignored by the RenderMode.
*
* Reading z-buffer as RGBA16:
* bbbmm mmmmm mmmmd d
* rrrrr ggggg bbbbb a
*
* The red increases monotonically with the depth. The significant visible oscillation is the green component, because
* it rolls over every time the second-most-significant bit of the mantissa increments. The blue component oscillates
* too rapidly to be particularly visible (it rolls over when the 7th-most-significant bit increments). The alpha is
* again ignored by the RenderMode.
*/
#include "gfx.h"
#include "vis.h"
// Height of the fragments the z-buffer is split into.
// It is the maximum amount of lines such that all rgba16 SCREEN_WIDTH-long lines fit into TMEM.
#define VISZBUF_ZBUFFRAG_HEIGHT (TMEM_SIZE / (SCREEN_WIDTH * G_IM_SIZ_16b_BYTES))
// z-buffer
extern u16 D_0E000000[];
/**
* Initialise to IA type with white and black as default colors.
*/
void VisZBuf_Init(VisZBuf* this) {
this->vis.type = VIS_ZBUF_TYPE_IA;
this->vis.scissorType = VIS_NO_SETSCISSOR;
this->vis.primColor.r = 255;
this->vis.primColor.g = 255;
this->vis.primColor.b = 255;
this->vis.primColor.a = 255;
// clang-format off
this->vis.envColor.r = 0; \
this->vis.envColor.g = 0; \
this->vis.envColor.b = 0; \
this->vis.envColor.a = 255;
// clang-format on
}
void VisZBuf_Destroy(VisZBuf* this) {
}
void VisZBuf_Draw(VisZBuf* this, Gfx** gfxP) {
Gfx* gfx = *gfxP;
s32 pad;
u16* zbufFrag = D_0E000000;
s32 fmt;
s32 y;
s32 height;
if (this->vis.type == VIS_ZBUF_TYPE_IA) {
fmt = G_IM_FMT_IA;
} else { // VIS_ZBUF_TYPE_RGBA
fmt = G_IM_FMT_RGBA;
}
height = VISZBUF_ZBUFFRAG_HEIGHT;
gDPPipeSync(gfx++);
// Scissoring is only required if the scissor has not been set prior.
if (this->vis.scissorType == VIS_SETSCISSOR) {
gDPSetScissor(gfx++, G_SC_NON_INTERLACE, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
}
// No palette so can use all of TMEM.
// G_RM_OPA_SURF discards all information previously in the pixel, and the current alpha, leaving only the color
// from this filter.
gDPSetOtherMode(gfx++,
G_AD_DISABLE | G_CD_MAGICSQ | G_CK_NONE | G_TC_FILT | G_TF_POINT | G_TT_NONE | G_TL_TILE |
G_TD_CLAMP | G_TP_NONE | G_CYC_1CYCLE | G_PM_NPRIMITIVE,
G_AC_NONE | G_ZS_PRIM | G_RM_OPA_SURF | G_RM_OPA_SURF2);
// LERP between primColor and envColor in 1-cycle mode using the z-buffer value.
gDPSetCombineLERP(gfx++, PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT, PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT,
PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT, PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT);
gDPSetColor(gfx++, G_SETPRIMCOLOR, this->vis.primColor.rgba);
gDPSetColor(gfx++, G_SETENVCOLOR, this->vis.envColor.rgba);
for (y = 0; y <= SCREEN_HEIGHT - height; y += height) {
// Load a few lines of the z-buffer, as many as can fit in TMEM at once.
gDPLoadTextureBlock(gfx++, zbufFrag, fmt, G_IM_SIZ_16b, SCREEN_WIDTH, height, 0, G_TX_NOMIRROR | G_TX_CLAMP,
G_TX_NOMIRROR | G_TX_CLAMP, G_TX_NOMASK, G_TX_NOMASK, G_TX_NOLOD, G_TX_NOLOD);
// Overwrite them with the calculated colors.
gSPTextureRectangle(gfx++, 0, y << 2, SCREEN_WIDTH << 2, (y + height) << 2, G_TX_RENDERTILE, 0, 0, 1 << 10,
1 << 10);
zbufFrag += SCREEN_WIDTH * height;
}
gDPPipeSync(gfx++);
*gfxP = gfx;
}
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