[英]How to Load Multiple Texture using OpenGL and C++?
在我之前的問題在這里使用OpenGL和Obj-C交換圖像之后,我決定也繼續使用帶有着色器和紋理的C ++的原始教程 。 我想做的是切換不同的紋理。 這是我的[更新]代碼
#include <iostream>
#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include "SOIL2/SOIL2.h"
#include "Shader.h"
using namespace std;
//window
const GLuint WIDTH = 750, HEIGHT = 750;
int main( )
{
glfwInit( );
//GLFW
glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 3 );
glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 3 );
glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );
glfwWindowHint( GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE ); //only for mac
glfwWindowHint( GLFW_RESIZABLE, GL_FALSE );
GLFWwindow *window = glfwCreateWindow( WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr );
int screenWidth, screenHeight;
glfwGetFramebufferSize( window, &screenWidth, &screenHeight );
if ( nullptr == window )
{
cout << "Failed to create GLFW window" << endl;
glfwTerminate( );
return EXIT_FAILURE;
}
glfwMakeContextCurrent( window );
//ModernOpenGL
glewExperimental = GL_TRUE;
if ( GLEW_OK != glewInit( ) )
{
cout << "Failed to initialize GLEW" << endl;
return EXIT_FAILURE;
}
//viewport
glViewport( 0, 0, screenWidth, screenHeight );
//enable alpha
glEnable( GL_BLEND );
glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
//shaders
Shader ourShader( "resources/shaders/core.vs", "resources/shaders/core.frag" );
//vertices
GLfloat vertices[] =
{
//position //color //texture Coords
1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // Top Right
1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // Bottom Right
-1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // Bottom Left
-1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // Top Left
};
GLuint indices[] =
{
0, 1, 3, // 1st triangle
1, 2, 3 // 2nd triangle
};
GLuint VBO, VAO, EBO;
glGenVertexArrays( 1, &VAO );
glGenBuffers( 1, &VBO );
glGenBuffers( 1, &EBO );
glBindVertexArray( VAO );
glBindBuffer( GL_ARRAY_BUFFER, VBO );
glBufferData( GL_ARRAY_BUFFER, sizeof( vertices ), vertices, GL_STATIC_DRAW );
glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, EBO );
glBufferData( GL_ELEMENT_ARRAY_BUFFER, sizeof( indices ), indices, GL_STATIC_DRAW );
//position
glVertexAttribPointer( 0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof( GLfloat ), ( GLvoid * ) 0 );
glEnableVertexAttribArray(0);
//color
glVertexAttribPointer( 1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof( GLfloat ), ( GLvoid * )( 3 * sizeof( GLfloat )));
glEnableVertexAttribArray(1);
//texture Coord
glVertexAttribPointer( 2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof( GLfloat ), ( GLvoid * )( 6 * sizeof( GLfloat )));
glEnableVertexAttribArray( 2 );
glBindVertexArray( 0 ); // unbind VAO
//CREATE TEXTURE
GLuint textures[2];
glGenTextures(2, textures);
int width, height;
unsigned char * image;
//texture1
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textures[0]);
image = SOIL_load_image("resources/res/images/green.png", &width, &height, 0, SOIL_LOAD_RGBA);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);
SOIL_free_image_data(image);
// glUniform1i(glGetUniformLocation(ourShader.Program, "ourTexture1"), 0);
glBindTexture(GL_TEXTURE_2D, textures[0]);
//texture2
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, textures[1]);
image = SOIL_load_image("resources/res/images/img1.png", &width, &height, 0, SOIL_LOAD_RGBA);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);
SOIL_free_image_data(image);
glUniform1i(glGetUniformLocation(ourShader.Program, "ourTexture2"), 1);
glBindTexture(GL_TEXTURE_2D, textures[1]);
//parameters
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
//filtering
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glGenerateMipmap( GL_TEXTURE_2D );
//loop
while ( !glfwWindowShouldClose( window ) )
{
glfwPollEvents( );
//render
glClearColor( 0.2f, 0.3f, 0.3f, 1.0f );
glClear( GL_COLOR_BUFFER_BIT );
//draw triangle
//if
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textures[0]);
glUniform1i(glGetUniformLocation(ourShader.Program, "ourTexture1"), 0);
//draw container
glBindVertexArray( VAO );
glDrawElements( GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0 );
glBindVertexArray( 0 );
glfwSwapBuffers( window );
}
//de-alocated stuff
glDeleteVertexArrays( 1, &VAO );
glDeleteBuffers( 1, &VBO );
glDeleteBuffers( 1, &EBO );
glfwTerminate( );
return EXIT_SUCCESS;
}
這是質地碎片
#version 330 core
in vec3 ourColor;
in vec2 TexCoord;
out vec4 color;
uniform sampler2D ourTexture1;
uniform sampler2D ourTexture2;
uniform int usetexture = 0;
void main()
{
if (usetexture == 0)
color = texture(ourTexture1, TexCoord);
if (usetexture == 1)
color = texture(ourTexture1, TexCoord);
}
如何正確調用它們並使其切換? 甚至沒有一種紋理也沒有顯示。 我想從SOIL加載圖像中的img1和img2之間切換。 但是已經被卡住了。 有什么建議嗎?
您必須將第一個紋理綁定到紋理單元0( GL_TEXTURE0
),並將第二個紋理綁定到紋理單元1( GL_TEXTURE1
):
GLuint textures[2];
int width, height;
unsigned char * image;
glGenTextures(2, textures);
// testure 1
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textures[0]);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
image = SOIL_load_image("resources/res/images/green.png", &width, &height, 0, SOIL_LOAD_RGBA);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);
SOIL_free_image_data(image);
// texture 2
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, textures[1]);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
image = SOIL_load_image("resources/res/images/red.png", &width, &height, 0, SOIL_LOAD_RGBA);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
SOIL_free_image_data(image);
紋理采樣器的ourTexture1
值ourTexture1
和ourTexture2
的值,分別是紋理單元0和1的編號。在將着色器程序對象作為當前渲染狀態的一部分安裝后,可以設置glUseProgram
( glUseProgram
):
// complie shaders and link shader program (glLinkProgram)
Shader ourShader( "resources/shaders/core.vs", "resources/shaders/core.frag" );
GLint tex1_loc = glGetUniformLocation( ourShader.Program, "ourTexture1" );
GLint tex2_loc = glGetUniformLocation( ourShader.Program, "ourTexture2" );
glUseProgram( ourShader.Program );
glUniform1i( tex1_loc, 0 );
glUniform1i( tex2_loc, 1 );
要在紋理之間選擇/切換,我建議使用glsl函數mix
。 該函數在2個值之間插值。
第3個參數是[0.0,1.0]范圍內的浮點值,它定義第1個參數和第2個參數之間的線性插值。 如果mix
的第三個參數為0.0,則函數的結果為第一個參數。 如果為1.0,則結果為第二個參數。
這使您可以創建兩種紋理的混合或完全利用它們。
片段着色器可能如下所示:
#version 330 core
in vec3 ourColor;
in vec2 TexCoord;
out vec4 color;
uniform sampler2D ourTexture1;
uniform sampler2D ourTexture2;
uniform float mixtexture;
void main()
{
vec4 color1 = texture(ourTexture1, TexCoord);
vec4 color2 = texture(ourTexture2, TexCoord);
color = mix(color1, color2, mixtexture);
}
要測試代碼,可以使用以下循環,該循環創建從ourTexture1
到ourTexture2
的過渡:
GLint mix_loc = glGetUniformLocation( ourShader.Program, "mixtexture" );
GLfloat mix_value = 0.0; // in [0.0, 1.0]
while ( !glfwWindowShouldClose( window ) )
{
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glUniform1f(mix_loc, mix_value);
mix_value = mix_value >= 1.0f ? 0.0f : mix_value + 0.01f;
glBindVertexArray( VAO );
glDrawElements( GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0 );
glBindVertexArray( 0 );
glfwSwapBuffers( window );
glfwPollEvents( );
}
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