使用SOIL在openGL中显示图像

Question

我正在尝试使用SDL和SOIL在openGL中显示图像，但它无法正常工作。

Globals.h

#include <SDL.h>
#include <SDL_OpenGL.h>
#include <SOIL.h>

#include "player.h"

的main.cpp

#include "Globals.h"

int main(int argc, char** argv){
    //Begin SDL initialization
    SDL_Init(SDL_INIT_EVERYTHING);
    SDL_Surface* Screen = SDL_SetVideoMode(800, 600, 32, SDL_SWSURFACE|SDL_OPENGL);
    SDL_Event Event;
    //End SDL initialization

    //Begin OpenGL initialization
    glClearColor(1, 1, 1, 1);//Set colour for empty screen
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glEnable(GL_BLEND);//Enable transparency
    glEnable(GL_TEXTURE_2D);

    glShadeModel(GL_SMOOTH);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    glOrtho(-400, 400, -300, 300, -1, 1);//Set grid for display

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    //End OpenGL initialization

    Player Player(0, 0, 32, 64, 1, 0, 0, 0.5);
    bool gameRunning = true;

    while(gameRunning){
        while(SDL_PollEvent(&Event)){
            if(Event.type == SDL_QUIT)
                gameRunning = false;
                //If user closed the window in any way stop gameRunning
            Player.Events(Event);
        }
        Player.Update();

        glClear(GL_COLOR_BUFFER_BIT);//Clear screen

        glPushMatrix();

        Player.DisplayWithImage("Brick.png", 32, 64);

        glPopMatrix();

        SDL_GL_SwapBuffers();//Update screen with new shit
    }

    SDL_Quit();//Quit SDL
    return 0;//End program
}

player.h

#pragma once

class Player{
public:
    GLfloat X, Y, W, H, R, G, B, A;
    bool movingUp, movingRight, movingDown, movingLeft;
    GLuint image;

    Player(GLfloat x, GLfloat y, GLfloat w, GLfloat h,
        GLfloat r, GLfloat g, GLfloat b, GLfloat a);
    void Events(SDL_Event &Event);
    void Update();
    void Display();
    void DisplayWithImage(const char* filename, GLsizei w, GLsizei h);
};

player.cpp

#include "Globals.h"

Player::Player(GLfloat x, GLfloat y, GLfloat w, GLfloat h, GLfloat r, GLfloat g, GLfloat b, GLfloat a){
    X = x;
    Y = y;
    W = w;
    H = h;
    R = r;
    G = g;
    B = b;
    A = a;

    movingUp = false;
    movingRight = false;
    movingDown = false;
    movingLeft = false;
}

void Player::Events(SDL_Event &Event){
    if(Event.type == SDL_KEYDOWN){
        if(Event.key.keysym.sym == SDLK_w)
            movingUp = true;
        if(Event.key.keysym.sym == SDLK_d)
            movingRight = true;
        if(Event.key.keysym.sym == SDLK_s)
            movingDown = true;
        if(Event.key.keysym.sym == SDLK_a)
            movingLeft = true;
    }
    if(Event.type == SDL_KEYUP){
        if(Event.key.keysym.sym == SDLK_w)
            movingUp = false;
        if(Event.key.keysym.sym == SDLK_d)
            movingRight = false;
        if(Event.key.keysym.sym == SDLK_s)
            movingDown = false;
        if(Event.key.keysym.sym == SDLK_a)
            movingLeft = false;
    }
}

void Player::Update(){
    if(movingUp)
        Y ++;
    if(movingRight)
        X ++;
    if(movingDown)
        Y --;
    if(movingLeft)
        X --;
}

void Player::Display(){
    glBegin(GL_QUADS);

        glColor4f(R, G, B, A);

        //bottom right
        glVertex2f(X+(W/2), Y-(H/2));
        //top right
        glVertex2f(X+(W/2), Y+(H/2));
        //top left
        glVertex2f(X-(W/2), Y+(H/2));
        //bottom left
        glVertex2f(X-(W/2), Y-(H/2));

    glEnd();
}

void Player::DisplayWithImage(const char* filename, GLsizei w, GLsizei h){
    image = SOIL_load_OGL_texture // load an image file directly as a new OpenGL texture
    (
        filename,
        SOIL_LOAD_AUTO,
        SOIL_CREATE_NEW_ID,
        SOIL_FLAG_MIPMAPS | SOIL_FLAG_INVERT_Y | SOIL_FLAG_NTSC_SAFE_RGB | SOIL_FLAG_COMPRESS_TO_DXT
    );

    glBindTexture(GL_TEXTURE_2D, image);

    glBegin(GL_QUADS);

        //bottom right
        glTexCoord2f(0, 0); glVertex2f(X+(W/2), Y-(H/2));
        //top right
        glTexCoord2f(0, H); glVertex2f(X+(W/2), Y+(H/2));
        //top left
        glTexCoord2f(W, H); glVertex2f(X-(W/2), Y+(H/2));
        //bottom left
        glTexCoord2f(W, 0); glVertex2f(X-(W/2), Y-(H/2));

    glEnd();
}

Answer 1

您的代码中有三个问题：

1. GL_TEXTURE_2D使用规范化纹理坐标（ 0.0 - 1.0 ）。除非H和W 1.0 或更少，否则您不希望将它们用于纹理坐标。如果您只想在四边形中拉伸此纹理一次，请使用 1.0 代替W和H。

2. 最严重的问题： 您正在每个帧上创建一个新纹理，您应该加载纹理一次，然后将加载的纹理句柄传递给{ {1}}而不是让每次调用时都加载一个纹理。

3. DisplayWithImage (...)创建一个拼写 投影 矩阵，任何单独使用投影矩阵的GL操作（例如不

您可以通过以这种方式重写部分代码来更正项目符号3：

glOrtho (...)