From 3804b57d27bd67ab1b7d1a6e5b4ce0b75ba97bcb Mon Sep 17 00:00:00 2001
From: Benedict Gaster <benedict.gaster@gmail.com>
Date: Fri, 27 Nov 2020 22:42:37 +0000
Subject: [PATCH] added beginnings of context
---
.gitignore | 1 +
include/graphics.hpp | 38 +++++++++++++
src/graphics.cpp | 133 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 172 insertions(+)
create mode 100644 .gitignore
create mode 100644 include/graphics.hpp
create mode 100644 src/graphics.cpp
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f8305e7
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+a.out
\ No newline at end of file
diff --git a/include/graphics.hpp b/include/graphics.hpp
new file mode 100644
index 0000000..de445fa
--- /dev/null
+++ b/include/graphics.hpp
@@ -0,0 +1,38 @@
+/**
+ *
+ * \author Benedict R. Gaster
+ */
+#pragma once
+
+#include <vector>
+
+#include <SDL2/SDL.h>
+
+namespace uwe {
+ class Context {
+ public:
+ /** \brief Create a context
+ * \param width an integer setting the window width
+ * \param height an integer setting the window height
+ */
+ Context(int width, int height);
+ ~Context();
+
+ /// Output details of GPU backend and texture formats
+ void dump_renderer_info();
+
+ /// run the control loop, returns only when user exits
+ void run();
+ private:
+ int height_; ///< window height
+ int width_; ///< window width
+ int tex_width_; ///< texture width
+ int tex_height_; ///< texture height
+ SDL_Window* window_; ///< window handle
+ SDL_Renderer* renderer_; ///< graphics backend handle
+ SDL_Texture* texture_; ///< pixel buffer texture handle
+
+ std::vector< uint8_t > pixels_; ///< pixels representing framebuffer
+ };
+}
+
diff --git a/src/graphics.cpp b/src/graphics.cpp
new file mode 100644
index 0000000..e4501d1
--- /dev/null
+++ b/src/graphics.cpp
@@ -0,0 +1,133 @@
+#include <iostream>
+
+#include <graphics.hpp>
+#include <iomanip>
+#include <cstring>
+
+namespace uwe {
+
+ Context::Context(int width, int height) :
+ width_{width},
+ height_{height},
+ tex_width_{width},
+ tex_height_{height},
+ pixels_(tex_width_ * tex_height_ * 4, 0) {
+ SDL_Init( SDL_INIT_EVERYTHING );
+
+ window_ = SDL_CreateWindow(
+ "SDL2",
+ SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
+ width_, height_,
+ SDL_WINDOW_SHOWN);
+
+ renderer_ = SDL_CreateRenderer(
+ window_,
+ -1,
+ SDL_RENDERER_ACCELERATED);
+
+ texture_ = SDL_CreateTexture(
+ renderer_,
+ SDL_PIXELFORMAT_ARGB8888,
+ SDL_TEXTUREACCESS_STREAMING,
+ tex_width_,
+ tex_height_);
+ }
+
+ Context::~Context() {
+ SDL_DestroyRenderer( renderer_ );
+ SDL_DestroyWindow( window_ );
+ SDL_Quit();
+ }
+
+ void Context::run() {
+ SDL_Event event;
+ bool running = true;
+ bool useLocktexture = false;
+
+ unsigned int frames = 0;
+ Uint64 start = SDL_GetPerformanceCounter();
+
+ while( running )
+ {
+
+ SDL_SetRenderDrawColor( renderer_, 0, 0, 0, SDL_ALPHA_OPAQUE );
+ SDL_RenderClear( renderer_ );
+
+ while( SDL_PollEvent( &event ) ) {
+ if( ( SDL_QUIT == event.type ) ||
+ ( SDL_KEYDOWN == event.type && SDL_SCANCODE_ESCAPE == event.key.keysym.scancode ) )
+ {
+ running = false;
+ break;
+ }
+ if( SDL_KEYDOWN == event.type && SDL_SCANCODE_L == event.key.keysym.scancode )
+ {
+ useLocktexture = !useLocktexture;
+ std::cout << "Using " << ( useLocktexture ? "SDL_LockTexture() + memcpy()" : "SDL_UpdateTexture()" ) << std::endl;
+ }
+ }
+
+ // splat down some random pixels
+ for( unsigned int i = 0; i < 1000; i++ ) {
+ const unsigned int x = rand() % tex_width_;
+ const unsigned int y = rand() % tex_height_;
+
+ const unsigned int offset = ( tex_width_ * 4 * y ) + x * 4;
+ pixels_[ offset + 0 ] = rand() % 256; // b
+ pixels_[ offset + 1 ] = rand() % 256; // g
+ pixels_[ offset + 2 ] = rand() % 256; // r
+ pixels_[ offset + 3 ] = SDL_ALPHA_OPAQUE; // a
+ }
+
+ if( useLocktexture ) {
+ unsigned char* lockedPixels = nullptr;
+ int pitch = 0;
+ SDL_LockTexture(
+ texture_,
+ NULL,
+ reinterpret_cast< void** >( &lockedPixels ),
+ &pitch
+ );
+ std::memcpy( lockedPixels, pixels_.data(), pixels_.size() );
+ SDL_UnlockTexture( texture_ );
+ }
+ else {
+ SDL_UpdateTexture(
+ texture_,
+ NULL,
+ pixels_.data(),
+ tex_width_ * 4);
+ }
+
+ SDL_RenderCopy( renderer_, texture_, NULL, NULL );
+ SDL_RenderPresent( renderer_ );
+
+ frames++;
+ const uint64_t end = SDL_GetPerformanceCounter();
+ const static uint64_t freq = SDL_GetPerformanceFrequency();
+ const double seconds = ( end - start ) / static_cast< double >( freq );
+ if( seconds > 2.0 )
+ {
+ std::cout
+ << frames << " frames in "
+ << std::setprecision(1) << std::fixed << seconds << " seconds = "
+ << std::setprecision(1) << std::fixed << frames / seconds << " FPS ("
+ << std::setprecision(3) << std::fixed << ( seconds * 1000.0 ) / frames << " ms/frame)"
+ << std::endl;
+ start = end;
+ frames = 0;
+ }
+ }
+
+ }
+
+ void Context::dump_renderer_info() {
+ SDL_RendererInfo info;
+ SDL_GetRendererInfo( renderer_, &info );
+ std::cout << "Renderer name: " << info.name << std::endl;
+ std::cout << "Texture formats: " << std::endl;
+ for( uint32_t i = 0; i < info.num_texture_formats; i++ ) {
+ std::cout << SDL_GetPixelFormatName( info.texture_formats[i] ) << std::endl;
+ }
+ }
+}
\ No newline at end of file
--
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