代码实现：
1、在
SandboxLayer.cpp
里增加函数
LoadTexture()
用来加载这两个logo
LoadTexture()
代码：
static GLuint LoadTexture(const std::string& path)
{
int w, h, bits;
stbi_set_flip_vertically_on_load(1);
auto* pixels = stbi_load(path.c_str(), &w, &h, &bits, STBI_rgb);
GLuint textureID;
glCreateTextures(GL_TEXTURE_2D, 1, &textureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, w, h, 0, GL_RGB, GL_UNSIGNED_BYTE, pixels);
stbi_image_free(pixels);
return textureID;
}
2、在
SandboxLayer.h
里增加2个私有成员
3、在
OnAttach()
里使用
LoadTexture()
，以及在
vertices
里增加texture coordinates,再增加它的属性设置。
SandboxLayer.cpp
的
OnAttach()
函数代码：
void SandboxLayer::OnAttach()
{
EnableGLDebugging();
// Init here
m_Shader = std::unique_ptr<Shader>(Shader::FromGLSLTextFiles(
"assets/vert.glsl",
"assets/frag.glsl"
));
glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
float vertices[] = {
// position. // RGBA color. // texture.
-1.5f, -0.5f, 0.0f, 0.18f, 0.6f, 0.96f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.0f, 0.18f, 0.6f, 0.96f, 1.0f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.0f, 0.18f, 0.6f, 0.96f, 1.0f, 1.0f, 1.0f,
-1.5f, 0.5f, 0.0f, 0.18f, 0.6f, 0.96f, 1.0f, 0.0f, 1.0f,
0.5f, -0.5f, 0.0f, 1.0f, 0.93f, 0.24f, 1.0f, 0.0f, 0.0f,
1.5f, -0.5f, 0.0f, 1.0f, 0.93f, 0.24f, 1.0f, 1.0f, 0.0f,
1.5f, 0.5f, 0.0f, 1.0f, 0.93f, 0.24f, 1.0f, 1.0f, 1.0f,
0.5f, 0.5f, 0.0f, 1.0f, 0.93f, 0.24f, 1.0f, 0.0f, 1.0f
};
glCreateVertexArrays(1, &m_QuadVA);
glBindVertexArray(m_QuadVA);
glCreateBuffers(1, &m_QuadVB);
glBindBuffer(GL_ARRAY_BUFFER, m_QuadVB);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
// Treating the first attribute 0 as the position coordinates.
glEnableVertexArrayAttrib(m_QuadVB, 0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 9* sizeof(float), 0);
// Add another attribute 1 as the color.
glEnableVertexArrayAttrib(m_QuadVB, 1);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 9* sizeof(float), (const void*)12);
// Add another attribute 2 as the texture coordinates.
glEnableVertexArrayAttrib(m_QuadVB, 2);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 9* sizeof(float), (const void*)28);
uint32_t indices[] = {
0, 1, 2, 2, 3, 0,
4, 5, 6, 6, 7, 4
};
glCreateBuffers(1, &m_QuadIB);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_QuadIB);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
m_ChernoTex = LoadTexture("assets/Cherno.png");
m_HazelTex = LoadTexture("assets/Hazel.png");
}
4、设置我们的shader
vert.glsl
代码：
#version 450 core
layout (location = 0) in vec3 a_Position;
layout (location = 1) in vec4 a_Color;
layout (location = 2) in vec2 a_TexCoord;
uniform mat4 u_ViewProj;
uniform mat4 u_Transform;
out vec4 v_Color;
out vec2 v_TexCoord;
void main()
{
v_Color = a_Color;
v_TexCoord = a_TexCoord;
gl_Position = u_ViewProj * u_Transform * vec4(a_Position, 1.0);
}
frag.glsl
代码：
#version 450 core
layout (location = 0) out vec4 o_Color;
in vec4 v_Color;
in vec2 v_TexCoord;
void main()
{
o_Color = vec4(v_TexCoord, 0.0, 1.0);
}
5、运行效果
彩色的两个方块，可以通过滚轮放大缩小。
6、在
vertices
里增加texture index，再增加它的属性设置。
7、设置我们的shader
vert.glsl
代码：
#version 450 core
layout (location = 0) in vec3 a_Position;
layout (location = 1) in vec4 a_Color;
layout (location = 2) in vec2 a_TexCoord;
layout (location = 3) in float a_TexIndex;
uniform mat4 u_ViewProj;
uniform mat4 u_Transform;
out vec4 v_Color;
out vec2 v_TexCoord;
out float v_TexIndex;
void main()
{
v_Color = a_Color;
v_TexCoord = a_TexCoord;
v_TexIndex = a_TexIndex;
gl_Position = u_ViewProj * u_Transform * vec4(a_Position, 1.0);
}
frag.glsl
代码：
#version 450 core
layout (location = 0) out vec4 o_Color;
in vec4 v_Color;
in vec2 v_TexCoord;
in float v_TexIndex;
void main()
{
o_Color = vec4(v_TexIndex, v_TexIndex, v_TexIndex, 1.0);
}
8、运行效果
左边的texture index为0，右边的texture index为1。
9、最后一步。
Bind these textures to the correct texture slots, and then set up some code inside our fragment shader to actually sample from these textures.
在
SandboxLayer.cpp
里的
OnUpdate()
函数里增加下面这两行代码
在
SandboxLayer.cpp
里的
OnAttach()
函数里增加下面这4行代码
frag.glsl
代码：
#version 450 core
layout (location = 0) out vec4 o_Color;
in vec4 v_Color;
in vec2 v_TexCoord;
in float v_TexIndex;
uniform sampler2D u_Textures[2];
void main()
{
int index = int(v_TexIndex);
o_Color = texture(u_Textures[index], v_TexCoord);
}
10、运行效果
