Modified 3DS composite_scene example demonstrating GPU hang when one shader has a geo part and the other doesn't

main.c

#include <3ds.h>
#include <citro3d.h>
#include <citro2d.h>
#include <string.h>
#include "vshader_shbin.h"
#include "lenny.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))

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

static C3D_LightEnv lightEnv;
static C3D_Light light;
static C3D_LightLut lut_Spec;

static C3D_AttrInfo vbo_attrInfo;
static C3D_BufInfo vbo_bufInfo;
static void* vbo_data;
static float angleX = 0.0, angleY = 0.0;

static C2D_TextBuf staticTextBuf;
static C2D_Text txt_helloWorld;

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]);
  shaderProgramSetGsh(&program, &vshader_dvlb->DVLE[1], 4*3);

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

  // Configure attributes for use with the vertex shader
  AttrInfo_Init(&vbo_attrInfo);
  AttrInfo_AddLoader(&vbo_attrInfo, 0, GPU_FLOAT, 3); // v0=position
  AttrInfo_AddLoader(&vbo_attrInfo, 1, GPU_FLOAT, 3); // v1=normal

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

  // Configure buffers
  BufInfo_Init(&vbo_bufInfo);
  BufInfo_Add(&vbo_bufInfo, vbo_data, sizeof(vertex), 2, 0x10);

  static const C3D_Material material =
  {
    { 0.1f, 0.1f, 0.1f }, //ambient
    { 0.4f, 0.4f, 0.4f }, //diffuse
    { 0.5f, 0.5f, 0.5f }, //specular0
    { 0.0f, 0.0f, 0.0f }, //specular1
    { 0.0f, 0.0f, 0.0f }, //emission
  };

  C3D_LightEnvInit(&lightEnv);
  C3D_LightEnvMaterial(&lightEnv, &material);

  LightLut_Phong(&lut_Spec, 20.0f);
  C3D_LightEnvLut(&lightEnv, GPU_LUT_D0, GPU_LUTINPUT_NH, false, &lut_Spec);

  C3D_LightInit(&light, &lightEnv);

  // Create text buffer
  staticTextBuf = C2D_TextBufNew(128);
  C2D_TextParse(&txt_helloWorld, staticTextBuf, "Hello, citro2d world!");
  C2D_TextOptimize(&txt_helloWorld);
}

static void sceneBind(void)
{
  C3D_BindProgram(&program);
  C3D_SetAttrInfo(&vbo_attrInfo);
  C3D_SetBufInfo(&vbo_bufInfo);
  C3D_LightEnvBind(&lightEnv);
  C3D_DepthTest(true, GPU_GREATER, GPU_WRITE_ALL);
  C3D_CullFace(GPU_CULL_BACK_CCW);

  // Configure the first fragment shading substage to blend the fragment primary color
  // with the fragment secondary color.
  // See https://www.opengl.org/sdk/docs/man2/xhtml/glTexEnv.xml for more insight
  C3D_TexEnv* env = C3D_GetTexEnv(0);
  C3D_TexEnvInit(env);
  C3D_TexEnvSrc(env, C3D_Both, GPU_FRAGMENT_PRIMARY_COLOR, GPU_FRAGMENT_SECONDARY_COLOR, 0);
  C3D_TexEnvFunc(env, C3D_Both, GPU_ADD);

  // Clear out the other texenvs
  C3D_TexEnvInit(C3D_GetTexEnv(1));
  C3D_TexEnvInit(C3D_GetTexEnv(2));
  C3D_TexEnvInit(C3D_GetTexEnv(3));
  C3D_TexEnvInit(C3D_GetTexEnv(4));
  C3D_TexEnvInit(C3D_GetTexEnv(5));
}

static void sceneRender(float iod)
{
  // Bind the program to render the VBO scene
  sceneBind();

  // Compute the projection matrix
  Mtx_PerspStereoTilt(&projection, C3D_AngleFromDegrees(40.0f), C3D_AspectRatioTop, 0.01f, 1000.0f, iod, 2.0f, false);

  C3D_FVec objPos   = FVec4_New(0.0f, 0.0f, -3.0f, 1.0f);
  C3D_FVec lightPos = FVec4_New(0.0f, 0.0f, -0.5f, 1.0f);

  // Calculate the modelView matrix
  C3D_Mtx modelView;
  Mtx_Identity(&modelView);
  Mtx_Translate(&modelView, objPos.x, objPos.y, objPos.z, true);
  Mtx_RotateY(&modelView, C3D_Angle(angleY), true);
  Mtx_Scale(&modelView, 2.0f, 2.0f, 2.0f);

  C3D_LightPosition(&light, &lightPos);

  // Update the uniforms
  C3D_FVUnifMtx4x4(GPU_VERTEX_SHADER, uLoc_projection, &projection);
  C3D_FVUnifMtx4x4(GPU_VERTEX_SHADER, uLoc_modelView,  &modelView);

  // Draw the VBO
  C3D_DrawArrays(GPU_GEOMETRY_PRIM, 0, vertex_list_count);

  // Draw the 2d scene
  C2D_Prepare();
  C2D_DrawText(&txt_helloWorld, 0, 8.0f, 8.0f, 1.0f, 1.0f, 1.0f);
  C2D_Flush();
}

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

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

int main()
{
  // Initialize graphics
  gfxInitDefault();
  gfxSet3D(true); // Enable stereoscopic 3D
  consoleInit(GFX_BOTTOM, NULL);
  C3D_Init(C3D_DEFAULT_CMDBUF_SIZE);
  C2D_Init(C2D_DEFAULT_MAX_OBJECTS);

  // Initialize the render targets
  C3D_RenderTarget* targetLeft  = C3D_RenderTargetCreate(240, 400, GPU_RB_RGBA8, GPU_RB_DEPTH24_STENCIL8);
  C3D_RenderTarget* targetRight = C3D_RenderTargetCreate(240, 400, GPU_RB_RGBA8, GPU_RB_DEPTH24_STENCIL8);
  C3D_RenderTargetSetOutput(targetLeft,  GFX_TOP, GFX_LEFT,  DISPLAY_TRANSFER_FLAGS);
  C3D_RenderTargetSetOutput(targetRight, GFX_TOP, GFX_RIGHT, DISPLAY_TRANSFER_FLAGS);

  // Initialize the scene
  sceneInit();

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

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

    float slider = osGet3DSliderState();
    float iod = slider/3;

    // Rotate the model
    if (!(kHeld & KEY_A))
    {
      angleX += 1.0f/64;
      angleY += 1.0f/256;
    }

    // Render the scene
    C3D_FrameBegin(C3D_FRAME_SYNCDRAW);
    {
      C3D_RenderTargetClear(targetLeft, C3D_CLEAR_ALL, CLEAR_COLOR, 0);
      C3D_FrameDrawOn(targetLeft);
      C2D_SceneTarget(targetLeft);
      sceneRender(-iod);

      if (iod > 0.0f)
      {
        C3D_RenderTargetClear(targetRight, C3D_CLEAR_ALL, CLEAR_COLOR, 0);
        C3D_FrameDrawOn(targetRight);
        C2D_SceneTarget(targetRight);
        sceneRender(iod);
      }
    }
    C3D_FrameEnd(0);
  }

  // Deinitialize the scene
  sceneExit();

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

vshader.g.pica

; Example PICA200 geometry shader
.gsh point c0

; Constants

; Outputs - this time the type *is* used
.out oPosition  position
.out oColor     color
.out oView      view
.out oNQ        normalquat

; Inputs: we will receive the following inputs:
; v0-v3:  data of the first vertex
; v4-v7:  data of the second vertex
; v8-v11: data of the third vertex

; Inputs
.in iPosition_1 v0
.in iColor_1    v1
.in iView_1     v2
.in iNQ_1       v3
.in iPosition_2 v4
.in iColor_2    v5
.in iView_2     v6
.in iNQ_2       v7
.in iPosition_3 v8
.in iColor_3    v9
.in iView_3     v10
.in iNQ_3       v11

.entry render2d_gmain
.proc render2d_gmain
  setemit 0
  mov oPosition, iPosition_1
  mov oColor,    iColor_1
  mov oView,     iView_1
  mov oNQ,       iNQ_1
  emit

  ; Emit the second vertex
  setemit 1
  mov oPosition, iPosition_2
  mov oColor,    iColor_2
  mov oView,     iView_2
  mov oNQ,       iNQ_2
  emit

  ; Emit the third vertex and finish the primitive
  setemit 2, prim
  mov oPosition, iPosition_3
  mov oColor,    iColor_3
  mov oView,     iView_3
  mov oNQ,       iNQ_3
  emit

  end
.end