shadow map sampling

main.c

#include <3ds.h>
#include <stdio.h>
#include <citro3d.h>
#include <string.h>
#include "vshader_shbin.h"

#define CLEAR_COLOR 0x68B0D8FF

#define DISPLAY_TRANSFER_FLAGS \
	(GX_TRANSFER_FLIP_VERT(0) | GX_TRANSFER_OUT_TILED(0) | GX_TRANSFER_RAW_COPY(0) | \
	GX_TRANSFER_IN_FORMAT(GX_TRANSFER_FMT_RGBA8) | GX_TRANSFER_OUT_FORMAT(GX_TRANSFER_FMT_RGB8) | \
	GX_TRANSFER_SCALING(GX_TRANSFER_SCALE_NO))

typedef struct { float x, y, z; } vertex;

static const vertex vertex_list[] =
{
	{ 200.0f, 200.0f, 0.5f },
	{ 100.0f, 40.0f, 0.5f },
	{ 300.0f, 40.0f, 0.5f },
};

#define vertex_list_count (sizeof(vertex_list)/sizeof(vertex_list[0]))

static DVLB_s* vshader_dvlb;
static shaderProgram_s program;
static int uLoc_projection, uLoc_texcoord;
static C3D_Mtx projection;

static void* vbo_data;

C3D_Tex tex;

void FillTex(u32 color) {
	u32* data = tex.data;
	for (unsigned i = 0; i < 8 * 8; ++i) {
		data[i] = color;
	}
	GSPGPU_FlushDataCache(data, 8 * 8 * 4);
}

void FillTexShadow(float d, float s) {
	u32 D = d * 0xFFFFFF;
	u8 S = s * 0xFF;
	u32 color = (u32)S << 24;
	color |= (D & 0xFF) << 16;
	color |= (D & 0xFF00);
	color |= (D & 0xFF0000) >> 16;
	FillTex(color);
}

float xTexZ = 0.8f, xBias = 0.2f;

static void sceneInit(void)
{
	// Load the vertex shader, create a shader program and bind it
	vshader_dvlb = DVLB_ParseFile((u32*)vshader_shbin, vshader_shbin_size);
	shaderProgramInit(&program);
	shaderProgramSetVsh(&program, &vshader_dvlb->DVLE[0]);
	C3D_BindProgram(&program);

	// Get the location of the uniforms
	uLoc_projection = shaderInstanceGetUniformLocation(program.vertexShader, "projection");
	uLoc_texcoord = shaderInstanceGetUniformLocation(program.vertexShader, "texcoord");

	// Configure attributes for use with the vertex shader
	C3D_AttrInfo* attrInfo = C3D_GetAttrInfo();
	AttrInfo_Init(attrInfo);
	AttrInfo_AddLoader(attrInfo, 0, GPU_FLOAT, 3); // v0=position
	AttrInfo_AddFixed(attrInfo, 1); // v1=color

	// Set the fixed attribute (color) to solid white
	C3D_FixedAttribSet(1, 1.0, 1.0, 1.0, 1.0);

	// Compute the projection matrix
	Mtx_OrthoTilt(&projection, 0.0, 400.0, 0.0, 240.0, 0.0, 1.0, true);

	// Create the VBO (vertex buffer object)
	vbo_data = linearAlloc(sizeof(vertex_list));
	memcpy(vbo_data, vertex_list, sizeof(vertex_list));

	// Configure buffers
	C3D_BufInfo* bufInfo = C3D_GetBufInfo();
	BufInfo_Init(bufInfo);
	BufInfo_Add(bufInfo, vbo_data, sizeof(vertex), 1, 0x0);

	// Configure the first fragment shading substage to just pass through the vertex color
	// See https://www.opengl.org/sdk/docs/man2/xhtml/glTexEnv.xml for more insight
	C3D_TexEnv* env = C3D_GetTexEnv(0);
	C3D_TexEnvSrc(env, C3D_Both, GPU_TEXTURE0, 0, 0);
	C3D_TexEnvOp(env, C3D_Both, 0, 0, 0);
	C3D_TexEnvFunc(env, C3D_Both, GPU_REPLACE);

	//C3D_TexInitShadow(&tex, 8, 8);
	C3D_TexInitWithParams(&tex, NULL,
		(C3D_TexInitParams){ 8, 8, 0, GPU_RGBA8, GPU_TEX_SHADOW_2D, false });
	C3D_TexBind(0, &tex);
	FillTexShadow(0.7, 0.6);
}



static void sceneRender(void)
{
	// Update the uniforms
	C3D_FVUnifMtx4x4(GPU_VERTEX_SHADER, uLoc_projection, &projection);

	C3D_FVUnifSet(GPU_VERTEX_SHADER, uLoc_texcoord, 0.1f, 0.1f, xTexZ, 0.0f);

	C3D_TexShadowParams(false, xBias);

	// Draw the VBO
	C3D_DrawArrays(GPU_TRIANGLES, 0, vertex_list_count);
}

static void sceneExit(void)
{
	// Free the VBO
	linearFree(vbo_data);

	// Free the shader program
	shaderProgramFree(&program);
	DVLB_Free(vshader_dvlb);
}

void updateText() {
    consoleClear();
	printf("TexZ = %f\n", xTexZ);
	printf("Bias = %f\n", xBias);
}

static PrintConsole bottomScreen;
int main()
{
	// Initialize graphics
	gfxInitDefault();
	consoleInit(GFX_BOTTOM, &bottomScreen);
	consoleSelect(&bottomScreen);
	gfxSetDoubleBuffering(GFX_BOTTOM, true);
	C3D_Init(C3D_DEFAULT_CMDBUF_SIZE);

	// Initialize the render target
	C3D_RenderTarget* target = C3D_RenderTargetCreate(240, 400, GPU_RB_RGBA8, GPU_RB_DEPTH24_STENCIL8);
	C3D_RenderTargetSetClear(target, C3D_CLEAR_ALL, CLEAR_COLOR, 0);
	C3D_RenderTargetSetOutput(target, GFX_TOP, GFX_LEFT, DISPLAY_TRANSFER_FLAGS);

	// Initialize the scene
	sceneInit();

	// Main loop
	while (aptMainLoop())
	{
		hidScanInput();

		// Respond to user input
		u32 kDown = hidKeysDown();
		if (kDown & KEY_START)
			break; // break in order to return to hbmenu

		if (kDown & KEY_A) {
			xTexZ += 0.2f;
			if (xTexZ > 2.0f)
				xTexZ = -1.0f;
		}

		if (kDown & KEY_B) {
			xBias += 0.2f;
			if (xBias > 1.0f)
				xBias = 0.0f;
		}

		// Render the scene
		C3D_FrameBegin(C3D_FRAME_SYNCDRAW);
			C3D_FrameDrawOn(target);
			sceneRender();
		C3D_FrameEnd(0);

		static int k = 0;

		if (k == 4)updateText();
		++k;
		k %= 8;
	}

	// Deinitialize the scene
	sceneExit();

	// Deinitialize graphics
	C3D_Fini();
	gfxExit();
	return 0;
}

vshader.v.pica

; Example PICA200 vertex shader

; Uniforms
.fvec projection[4]

; Constants
.constf myconst(0.0, 1.0, -1.0, 0.1)
.constf myconst2(0.3, 0.0, 0.0, 0.0)
.alias  zeros myconst.xxxx ; Vector full of zeros
.alias  ones  myconst.yyyy ; Vector full of ones

; Outputs
.out outpos position
.out outclr color
.out tex texcoord0
.out texw texcoord0w

; Inputs (defined as aliases for convenience)
.alias inpos v0
.alias inclr v1

.bool test

.fvec texcoord

.proc main
	; Force the w component of inpos to be 1.0
	mov r0.xyz, inpos
	mov r0.w,   ones

	; outpos = projectionMatrix * inpos
	dp4 outpos.x, projection[0], r0
	dp4 outpos.y, projection[1], r0
	dp4 outpos.z, projection[2], r0
	dp4 outpos.w, projection[3], r0

	; outclr = inclr
	mov outclr, inclr
	
	mov tex, texcoord
	mov texw, texcoord.zzzz

	; We're finished
	end
.end