Here is the function where I am calling all of my draw operations. I also compile the shaders inline in the function. It displays the quad correctly when I just use colors for each vertex but textures don't want to work at all. Also uniforms are all passing to the shaders as 0.
Here is the code:
void doGL2() {
glTranslatef(0.f, 0.f, 0.f);
const GLchar* vertShader[] = { R"glsl(
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
layout (location = 2) in vec2 aTexPos;
out vec3 col;
out vec2 texturePos;
void main()
{
gl_Position = vec4(aPos, 1.0);
col = aColor;
texturePos = aTexPos;
}
)glsl" };
const GLchar* fragShader[] = { R"glsl(
#version 330 core
out vec4 FragColor;
in vec3 col;
in vec2 texturePos;
uniform sampler2D t;
uniform vec2 iResolution;
void main()
{
vec2 uv = gl_FragCoord.xy / iResolution;
//FragColor = vec4(iResolution, 1., 1.);
FragColor = mix(vec4(col, 1.0f), texture(t, gl_FragCoord.xy / vec2(1200., 675.)), 1.);
}
)glsl" };
vShader2 = glCreateShader(GL_VERTEX_SHADER);
fShader2 = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(vShader2, 1, vertShader, NULL);
glCompileShader(vShader2);
GLint success;
GLchar infoLog[1024];
glGetShaderiv(vShader2, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(vShader2, 1024, NULL, infoLog);
throw std::runtime_error("\noh no vert\n");
}
glShaderSource(fShader2, 1, fragShader, NULL);
glCompileShader(fShader2);
glGetShaderiv(fShader2, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(fShader2, 1024, NULL, infoLog);
throw std::runtime_error("\noh no frag\n");
}
shaderProgram2 = glCreateProgram();
glAttachShader(shaderProgram2, vShader2);
glAttachShader(shaderProgram2, fShader2);
glLinkProgram(shaderProgram2);
GLfloat screen[2] = { 1200.0f, 675.0f };
glUseProgram(shaderProgram2);
glUniform2fv(glGetUniformLocation(shaderProgram2, "iResolution"), 2, screen);
glUniform1i(glGetUniformLocation(shaderProgram2, "t"), 0);
//not sure if I should do this on cleanup or now
glDeleteShader(vShader2);
glDeleteShader(fShader2);
//lets make a temporary test texture
int width, height, channels;
unsigned char* data = stbi_load("tex2.jpg", &width, &height, &channels, 4);
GLuint tempT = 1;
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &tempT);
glBindTexture(GL_TEXTURE_2D, tempT);
// set texture options
/*
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
*/
//glPixelStorei(GL_UNPACK_ALIGNMENT, 2);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
stbi_image_free(data);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, 1);
GLfloat vertices[] = {
// positions // colors // texture positions
0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, // bottom left
1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom right
1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f // top right
,
0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, // bottom left
0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, // top left
1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f // top right
};
glGenVertexArrays(1, &VAO2);
glGenBuffers(1, &VBO2);
glBindVertexArray(VAO2);
glBindBuffer(GL_ARRAY_BUFFER, VBO2);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
//positions
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
//colors
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
//texture positions
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);
float initTime = glutGet(GLUT_ELAPSED_TIME);
float prevTime = initTime;
float dt = 0.0f;
while (prevTime - initTime < 1000.0f) {
dt = (glutGet(GLUT_ELAPSED_TIME) - prevTime) / 1000.0f;
prevTime = glutGet(GLUT_ELAPSED_TIME);
glClearColor(1.f, 1.f, 1.f, 1.f);
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(VAO2);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, tempT);
glActiveTexture(GL_TEXTURE0);
glDrawArrays(GL_TRIANGLES, 0, 6);
SwapBuffers(GetDC(w));
glFlush();
}
}
For some reason, when I instead put the texture bound to GL_TEXTURE0 it displayed what looks like the average color of the texture.
Edit:
This is what the result is when I bind to GL_TEXTURE0 instead:
This is the input image:
Also I have changed the code to the code that outputs this result.
CodePudding user response：
If you are not generating mipmaps (with glGenerateMipmap) it is important to set GL_TEXTURE_MIN_FILTER. Since the default filter is GL_NEAREST_MIPMAP_LINEAR, the texture would be "Mipmap Incomplete" if you do not change the minimize function to GL_NEAREST or GL_LINEAR.
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
It is not guaranteed that stbi_load generates a texture with 4 color channels. Force the stbi_load to generate an image with 4 color channels, by explicitly pass 4 to the last parameter:
unsigned char* data = stbi_load("tex2.jpg", &width, &height, &channels, 0);
unsigned char* data = stbi_load("tex2.jpg", &width, &height, &channels, 4);
CodePudding user response：
I really should focus on debugging before I post on here, because again the solution to this was a very simple and silly error. In my line:
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
The parameters with values of 1 should actually be width and height. facepalm I was only loading the first pixel of the image.