160 lines
4.6 KiB
C++
160 lines
4.6 KiB
C++
#include <SDL.h>
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#include <SDL_image.h>
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#include <GLES/gl.h>
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GLuint texture;
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// I've tweaked coordinates a bit to my taste
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GLfloat textureCoordinates[] = { 0.0f, 1.0f,
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0.0f, 0.0f,
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1.0f, 0.0f,
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1.0f, 1.0f };
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GLfloat vertices[] = {
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100, 100,
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100, 300,
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300, 300,
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300, 100 };
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int loadImage() {
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SDL_Surface *pic;
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SDL_Surface *tmp;
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glGenTextures(1, &texture);
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glBindTexture(GL_TEXTURE_2D, texture);
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glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
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glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
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glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
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pic = IMG_Load("gradient.png");
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// check power of 2
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if (!pic || !pic->w || !pic->h || (pic->w & 1) || (pic->h & 1)) {
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return -1;
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}
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//uncomment for 32bit
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tmp = SDL_CreateRGBSurface(0, pic->w, pic->h, 32, 0x000000FF, 0x0000FF00, 0x00FF0000, 0xFF000000 );
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SDL_BlitSurface(pic, NULL, tmp, NULL);
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glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, pic->w, pic->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, tmp->pixels);
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/*
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//uncomment for 16bit
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tmp = SDL_CreateRGBSurface(0, pic->w, pic->h, 16, 0xF800, 0x7E0, 0x1F, 0); // Correct bits of RGB565 color format
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SDL_BlitSurface(pic, NULL, tmp, NULL);
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glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, pic->w, pic->h, 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, tmp->pixels);
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*/
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SDL_FreeSurface(pic);
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SDL_FreeSurface(tmp);
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return 0;
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}
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int width = 640;
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int height = 480;
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static void
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initGL()
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{
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glViewport(0, 0, width, height);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glOrthof(0.0f, width, 0.0f, height, -1.0f, 1.0f);
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glMatrixMode(GL_MODELVIEW);
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glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
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glDisable(GL_DEPTH_TEST);
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glEnable(GL_TEXTURE_2D);
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glEnableClientState(GL_VERTEX_ARRAY);
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glEnableClientState(GL_TEXTURE_COORD_ARRAY);
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glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
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}
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static void
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draw()
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{
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glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); // Always clear your scene before rendering, unless you're sure that you'll fill whole screen with textures/models etc
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// You have to this each frame, because SDL messes up with your GL context when drawing on-screen keyboard, however is taves/restores your matrices
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glColor4f(1.0f, 1.0f, 1.0f, 1.0f); // Just to be sure
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glEnable(GL_TEXTURE_2D);
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glDisable(GL_BLEND);
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glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
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glBindTexture(GL_TEXTURE_2D, texture);
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glEnableClientState(GL_VERTEX_ARRAY);
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glEnableClientState(GL_TEXTURE_COORD_ARRAY);
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glVertexPointer(2, GL_FLOAT, 0, vertices);
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glTexCoordPointer(2, GL_FLOAT, 0, textureCoordinates);
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glDrawArrays(GL_TRIANGLE_FAN, 0, 4); // You may just replace all your GL_QUADS with GL_TRIANGLE_FAN and it will draw absolutely identically with same coordinates, if you have just 4 coords.
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glDisableClientState(GL_VERTEX_ARRAY);
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glDisableClientState(GL_TEXTURE_COORD_ARRAY);
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}
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int
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main(int argc, char *argv[])
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{
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SDL_Surface *screen;
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int done;
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Uint8 *keys;
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SDL_Init(SDL_INIT_VIDEO);
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// Set native device screen resolution, if you want 640x480 select SdlVideoResize=y in AndroidAppSettings.cfg
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width = SDL_ListModes(NULL, 0)[0]->w;
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height = SDL_ListModes(NULL, 0)[0]->h;
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//32bit video mode
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screen = SDL_SetVideoMode(width, height, 16, SDL_OPENGL|SDL_DOUBLEBUF);
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if ( ! screen ) {
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fprintf(stderr, "Couldn't set GL video mode: %s\n", SDL_GetError());
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SDL_Quit();
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exit(2);
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}
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SDL_WM_SetCaption("test", "test");
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initGL();
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loadImage();
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while ( ! SDL_GetKeyState(NULL)[SDLK_ESCAPE] ) // Exit by pressing Back button
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{
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draw();
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SDL_GL_SwapBuffers();
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SDL_Event event;
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while( SDL_PollEvent(&event) ) ; // Do nothing, just process keyboard/mouse events internally
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// Some kinda animation
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SDL_Delay(10000);
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static float diff = 1.0f;
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vertices[0] += diff;
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vertices[2] += diff;
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vertices[4] += diff;
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vertices[6] += diff;
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if( vertices[4] > width )
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diff = -1.0f;
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if( vertices[0] < 0 )
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diff = 1.0f;
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}
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SDL_Quit();
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return 0;
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}
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