OpenGL Texture Shader not Working

Question

I am developing a program in OpenGl. My curent setup includes just one quad and a texture I want to render on it. The problem is that the texture doesn't render on to the quad. If I change the fragment shader to render a color it renders correctly.

Here is the render code:

glfwSwapBuffers(window);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


glUseProgram(programID);

glBindVertexArray(vaoID);
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
GL13.glActiveTexture(GL13.GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textureID);
glDrawElements(GL_TRIANGLES, indicies.length, GL_UNSIGNED_INT, 0);
glDisableVertexAttribArray(0);
glDisableVertexAttribArray(1);
glBindVertexArray(0);

glUseProgram(0);

Vertex shader:

#version 400 core

layout(location = 0) in vec3 position;
layout(location = 1) in vec2 textureCoords;

out vec2 pass_TextureCoords;

void main() {
    gl_Position = vec4(position, 1.0);
    pass_TextureCoords = textureCoords;
}

Fragmen shader:

#version 400 core

in vec2 pass_textureCoords;

out vec4 out_Color;

uniform sampler2D textureSampler;

void main() {
    out_Color = texture(textureSampler, pass_textureCoords);
}

Where's the code for setting up the vertex buffer?

Robinson
– Robinson

2015-08-20 09:44:41 +00:00
Commented Aug 20, 2015 at 9:44 — Robinson
– Robinson, Commented Aug 20, 2015 at 9:44

reden · Accepted Answer · 2015-08-20 14:45:04Z

0

You need to specify the uniform for textureSampler. Ie,

glUniform1i(textureSamplerHandle, 0);

Which you have retrieved from

textureSamplerHandle = glGetUniformLocation(shaderProgram, "textureSampler");

edited Aug 20, 2015 at 14:45

answered Aug 20, 2015 at 13:46

reden

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2 Comments

Reto Koradi Over a year ago

While generally a good idea, this is not necessary for the simple example. Sampler uniforms have a default value of 0, and the texture is bound to texture unit 0. So the default value is correct.

reden Over a year ago

My answer is incorrect, even, as I state "1" should be used when the example is using TEXTURE0. Corrected.

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