ppapi_simple

native_client_sdk/src/examples/demo/life/life.c

+// Copyright 2011 The Native Client SDK Authors. All rights reserved.

[binji, 2013/05/23 18:06:49]

2013

[noelallen1, 2013/05/30 18:07:18]

Done.

+// Use of this source code is governed by a BSD-style license that can
+// be found in the LICENSE file.
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "ppapi/c/pp_resource.h"
+#include "ppapi/c/ppb_core.h"
+#include "ppapi/c/ppb_graphics_2d.h"
+#include "ppapi/c/ppb_image_data.h"
+#include "ppapi/c/ppb_input_event.h"
+#include "ppapi/c/ppb_instance.h"
+#include "ppapi/c/ppb_view.h"
+
+#include "ppapi_simple/ppapi_event.h"
+#include "ppapi_simple/ppapi_simple_main.h"
+
+PPB_Core* g_pCore;
+PPB_Graphics2D* g_pGraphics2D;
+PPB_ImageData* g_pImageData;
+PPB_Instance* g_pInstance;
+PPB_View* g_pView;
+PPB_InputEvent* g_pInputEvent;
+PPB_KeyboardInputEvent* g_pKeyboardInput;
+PPB_MouseInputEvent* g_pMouseInput;
+PPB_TouchInputEvent* g_pTouchInput;
+
+struct {

[binji, 2013/05/23 18:06:49]

why store this is a struct instead of individual globals?

[noelallen1, 2013/05/23 22:01:24]

Just for organization reasons.

+  PP_Resource ctx_;

[binji, 2013/05/23 18:06:49]

public members for structs don't have trailing _

[noelallen1, 2013/05/23 22:01:24]

Done.

+  struct PP_Size size_;
+  int bound_;
+  uint8_t* cell_in_;
+  uint8_t* cell_out_;
+} g_Context;
+
+
+const unsigned int kInitialRandSeed = 0xC0DE533D;
+
+#define MakeRGBA(r, g, b, a)  \
+  (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))
+
+// Map of neighboring colors.

[binji, 2013/05/23 18:06:49]

these numbers seem pretty random. Maybe explain a bit more?

[noelallen1, 2013/05/23 22:01:24]

Done.

+const uint32_t kNeighborColors[] = {
+    MakeRGBA(0x00, 0x00, 0x00, 0xff),
+    MakeRGBA(0x00, 0x40, 0x00, 0xff),
+    MakeRGBA(0x00, 0x60, 0x00, 0xff),
+    MakeRGBA(0x00, 0x80, 0x00, 0xff),
+    MakeRGBA(0x00, 0xA0, 0x00, 0xff),
+    MakeRGBA(0x00, 0xC0, 0x00, 0xff),
+    MakeRGBA(0x00, 0xE0, 0x00, 0xff),
+    MakeRGBA(0x00, 0x00, 0x00, 0xff),
+    MakeRGBA(0x00, 0x40, 0x00, 0xff),
+    MakeRGBA(0x00, 0x60, 0x00, 0xff),
+    MakeRGBA(0x00, 0x80, 0x00, 0xff),
+    MakeRGBA(0x00, 0xA0, 0x00, 0xff),
+    MakeRGBA(0x00, 0xC0, 0x00, 0xff),
+    MakeRGBA(0x00, 0xE0, 0x00, 0xff),
+    MakeRGBA(0x00, 0xFF, 0x00, 0xff),
+    MakeRGBA(0x00, 0xFF, 0x00, 0xff),
+    MakeRGBA(0x00, 0xFF, 0x00, 0xff),
+    MakeRGBA(0x00, 0xFF, 0x00, 0xff),
+};
+
+// These represent the new health value of a cell based on its neighboring
+// values.  The health is binary: either alive or dead.
+const uint8_t kIsAlive[] = {
+      0, 0, 0, 1, 0, 0, 0, 0, 0,  // Values if the center cell is dead.
+      0, 0, 1, 1, 0, 0, 0, 0, 0  // Values if the center cell is alive.
+};
+
+
+void UpdateContext(uint32_t width, uint32_t height) {
+  size_t size = width * height;
+  size_t index;
+
+  free(g_Context.cell_in_);
+  free(g_Context.cell_out_);
+
+  //
+  // Create a new context
+  //
+  g_Context.cell_in_ = (uint8_t*) malloc(size);
+  g_Context.cell_out_ = (uint8_t*) malloc(size);
+
+  memset(g_Context.cell_out_, 0, size);
+  for (index = 0; index < size; index++) {
+    g_Context.cell_in_[index] = rand() & 1;
+  }
+}
+
+void ProcessEvent(PSEvent* event) {
+  static int mouse_down = 0;

[binji, 2013/05/23 18:06:49]

unused

[noelallen1, 2013/05/23 22:01:24]

Done.

+
+  switch(event->type_) {
+    /* If the view updates, build a new Graphics 2D Context */
+    case PS_VIEW_EVENT: {
+      struct PP_Rect rect;
+      int32_t width;
+      int32_t height;
+      if (g_Context.ctx_) {
+        g_pCore->ReleaseResource(g_Context.ctx_);
+        g_Context.ctx_ = 0;
+      }
+
+      g_pView->GetRect(event->resource_, &rect);
+      width = rect.size.width;
+      height = rect.size.height;
+
+      if (width != g_Context.size_.width || height != g_Context.size_.height) {
+        UpdateContext(rect.size.width, rect.size.height);
+      }
+      if (width != g_Context.size_.width || height != g_Context.size_.height ||
+          !g_Context.bound_) {
+        g_Context.ctx_ =
+            g_pGraphics2D->Create(PSGetInstanceId(), &rect.size, PP_TRUE);
+        g_Context.bound_ =
+            g_pInstance->BindGraphics(PSGetInstanceId(), g_Context.ctx_);
+        g_Context.size_ = rect.size;
+      }
+      break;
+    }
+
+    case PS_INPUT_EVENT: {

[nfullagar1, 2013/05/23 21:58:36]

I'm not super keen on how PS is defining a PS_INPUT_EVENT, but then further
below using PP_INPUTEVENT_TYPE_MOUSEMOVE.  For people new to PPAPI and PS,
there's a fairly subtle line here between the two.

[noelallen1, 2013/05/30 18:07:18]

Done.

+      PP_InputEvent_Type type = g_pInputEvent->GetType(event->resource_);
+      PP_InputEvent_Modifier modifiers =
+          g_pInputEvent->GetModifiers(event->resource_);
+      int32_t width = g_Context.size_.width;
+      int32_t height = g_Context.size_.height;
+
+      switch(type) {
+        case PP_INPUTEVENT_TYPE_MOUSEMOVE:
+          {
+            struct PP_Point location =
+                g_pMouseInput->GetPosition(event->resource_);
+
+            if (!g_Context.cell_in_) break;
+
+            // If the button is down, draw
+            if (modifiers & PP_INPUTEVENT_MODIFIER_LEFTBUTTONDOWN) {
+              int x = location.x;
+              int y = location.y;
+
+              if (x > 0 && x < width && y > 0 && y < height) {

[binji, 2013/05/23 18:06:49]

x < width - 1
y < height - 1

[noelallen1, 2013/05/23 22:01:24]

Done.

[binji, 2013/05/30 05:07:50]

Missed this one.

[noelallen1, 2013/05/30 18:07:18]

Done.

+                g_Context.cell_in_[x-1 + y * width] = 1;
+                g_Context.cell_in_[x+1 + y * width] = 1;
+                g_Context.cell_in_[x + (y - 1) * width] = 1;
+                g_Context.cell_in_[x + (y + 1) * width] = 1;
+              }
+            }
+          }
+          break;
+
+        case PP_INPUTEVENT_TYPE_KEYUP: {
+          if (g_pKeyboardInput->GetKeyCode(event->resource_) == 13) {

[binji, 2013/05/23 18:06:49]

enter key

[noelallen1, 2013/05/30 18:07:18]

Done.

+            // PSToggleFullscreen();

[binji, 2013/05/23 18:06:49]

does this not work?

[noelallen1, 2013/05/23 22:01:24]

Done.

+          }
+          break;
+        }
+
+        default:
+          break;
+      }
+      break;
+    }
+
+    default:
+      break;
+  }
+}
+
+
+void Stir(uint32_t width, uint32_t height) {
+  int i;
+  if (g_Context.cell_in_ == NULL || g_Context.cell_out_ == NULL)
+    return;
+
+  for (i = 0; i < width; ++i) {
+    g_Context.cell_in_[i] = rand() & 1;

[binji, 2013/05/23 18:06:49]

probably not a big deal, but I always heard that the low bits of rand() were
less random than the high bits...

+    g_Context.cell_in_[i + (height - 1) * width] = rand() & 1;
+  }
+  for (i = 0; i < height; ++i) {
+    g_Context.cell_in_[i * width] = rand() & 1;
+    g_Context.cell_in_[i * width + (width - 1)] = rand() & 1;
+  }
+}
+
+void Render() {
+  struct PP_Size* psize = &g_Context.size_;
+  PP_ImageDataFormat format = g_pImageData->GetNativeImageDataFormat();
+  PP_Resource image =
+      g_pImageData->Create(PSGetInstanceId(), format, psize, PP_FALSE);

[binji, 2013/05/23 18:06:49]

seems strange to create a new image every frame. Maybe explain that this is
cached...?

[noelallen1, 2013/05/23 22:01:24]

Done.

+  uint8_t* pixels = g_pImageData->Map(image);
+
+  struct PP_ImageDataDesc desc;
+  uint8_t* cell_temp;
+  uint32_t x, y;
+
+  // If we somehow have not allocated these pointers yet, skip this frame.
+  if (!g_Context.cell_in_ || !g_Context.cell_out_) return;
+
+  // Get the stride
+  g_pImageData->Describe(image, &desc);

[nfullagar1, 2013/05/23 21:58:36]

For consistency, use the desc.size.width & height for the rest of this function,
instead of mixing psize->width, psize->height with desc.stride.  It is a bit
clearer, as the |desc| is from imagedata -- same as |pixels| (whereas psize came
from context.)

[noelallen1, 2013/05/24 18:08:31]

Done.

+
+  // Stir up the edges to prevent the simulation from reaching steady state.
+  Stir(psize->width, psize->height);
+
+  // Do neighbor sumation; apply rules, output pixel color.

[binji, 2013/05/23 18:06:49]

sp: summation

[noelallen1, 2013/05/23 22:01:24]

Done.

+  for (y = 1; y < (psize->height - 1); ++y) {

[binji, 2013/05/23 18:06:49]

why ()?

[noelallen1, 2013/05/23 22:01:24]

Done.

+    uint8_t *src0 = (g_Context.cell_in_ + (y - 1) * psize->width) + 1;
+    uint8_t *src1 = src0 + psize->width;
+    uint8_t *src2 = src1 + psize->width;
+    int count;
+    uint32_t color;
+    uint8_t *dst = (g_Context.cell_out_ + (y) * psize->width) + 1;

[binji, 2013/05/23 18:06:49]

why (y)?

[noelallen1, 2013/05/23 22:01:24]

Done.

+    uint32_t *pixel_line =  (uint32_t*) (pixels + y * desc.stride);
+
+    for (x = 1; x < (psize->width - 1); ++x) {
+      // Build sum, weight center by 9x.
+      count = src0[-1] + src0[0] +     src0[1] +
+              src1[-1] + src1[0] * 9 + src1[1] +
+              src2[-1] + src2[0] +     src2[1];
+      color = kNeighborColors[count];
+
+      *pixel_line++ = color;
+      *dst++ = kIsAlive[count];
+      ++src0;
+      ++src1;
+      ++src2;
+    }
+  }
+
+  cell_temp = g_Context.cell_in_;
+  g_Context.cell_in_ = g_Context.cell_out_;
+  g_Context.cell_out_ = cell_temp;
+
+  /* Unmap the range, we no longer need it. */
+  g_pImageData->Unmap(image);
+
+  /* Replace the contexts, and block until it's on the screen. */
+  g_pGraphics2D->ReplaceContents(g_Context.ctx_, image);
+  g_pGraphics2D->Flush(g_Context.ctx_, PP_BlockUntilComplete());
+
+  /* Release the image data, we no longer need it. */
+  g_pCore->ReleaseResource(image);
+}
+
+
+int my_main(int argc, const char *argv[]) {

[binji, 2013/05/23 18:06:49]

might want to mention this can be called anything but main.

[noelallen1, 2013/05/23 22:01:24]

Done.

+  fprintf(stdout,"Started main.\n");
+  g_pCore = (PPB_Core*)PSGetInterface(PPB_CORE_INTERFACE);
+  g_pGraphics2D = (PPB_Graphics2D*)PSGetInterface(PPB_GRAPHICS_2D_INTERFACE);
+  g_pInstance = (PPB_Instance*)PSGetInterface(PPB_INSTANCE_INTERFACE);
+  g_pImageData = (PPB_ImageData*)PSGetInterface(PPB_IMAGEDATA_INTERFACE);
+  g_pView = (PPB_View*)PSGetInterface(PPB_VIEW_INTERFACE);
+
+  g_pInputEvent =
+      (PPB_InputEvent*) PSGetInterface(PPB_INPUT_EVENT_INTERFACE);
+  g_pKeyboardInput = (PPB_KeyboardInputEvent*)
+      PSGetInterface(PPB_KEYBOARD_INPUT_EVENT_INTERFACE);
+  g_pMouseInput =
+      (PPB_MouseInputEvent*) PSGetInterface(PPB_MOUSE_INPUT_EVENT_INTERFACE);
+  g_pTouchInput =

[binji, 2013/05/23 18:06:49]

unused

[noelallen1, 2013/05/30 18:07:18]

Done.

+      (PPB_TouchInputEvent*) PSGetInterface(PPB_TOUCH_INPUT_EVENT_INTERFACE);
+
+  PSSetEventFilter(PS_ALL_EVENTS);
+  while (1) {
+    /* Process all waiting events without blocking */
+    PSEvent* event;
+    while ((event = PSAcquireEvent(0)) != NULL) {

[binji, 2013/05/23 18:06:49]

what is 0?

[noelallen1, 2013/05/23 22:01:24]

Means don't block, see comment above.

+      ProcessEvent(event);
+      PSReleaseEvent(event);
+    }
+
+    /* Render a frame, blocking until complete. */
+    if (g_Context.bound_) {
+      Render();
+    }
+  }
+  return 0;
+}
+

[nfullagar1, 2013/05/23 21:58:36]

How would this sample differ if PPAPI_SIMPLE_MAIN2D was used? (below)

[noelallen1, 2013/05/24 18:08:31]

The idea is that PPAPI_SIMPLE_MAIN2D would automate more of this.  It would
provide helpers for building and maintaining the 2D context, and for allocating
and freeing the image data.  It should be possible to re-write this without
g_pView, g_pImageData, and g_pGraphics2D.

+PPAPI_SIMPLE_MAIN(my_main);

[binji, 2013/05/23 18:06:49]

what is this doing? Maybe a little comment.

[noelallen1, 2013/05/23 22:01:24]

Done.