Texture mapping using a 1d texture with OpenGL 4.x - opengl

Question

I want to use a 1d texture (color ramp) to texture a simple triangle.
My fragment shader looks like this:
#version 420
uniform sampler1D colorRamp;
in float height;
out vec4 FragColor;
void main()
{
FragColor = texture(colorRamp, height).rgba;
}
My vertex shader looks like this:
#version 420
layout(location = 0) in vec3 position;
out float height;
void main()
{
height = (position.y + 0.75f) / (2 * 0.75f);
gl_Position = vec4( position, 1.0);
}
When drawing the triangle I proceed this way (I removed error checking form code for better readability):
glUseProgram(program_);
GLuint samplerLocation = glGetUniformLocation(program_, name.toCString());
glUniform1i(samplerLocation, currentTextureUnit_);
glActiveTexture( GL_TEXTURE0 + currentTextureUnit_ );
glBindTexture(GL_TEXTURE_1D, textureId);
Unfortunately my triangle is only black. Any ideas how to solve this issue?
I am pretty sure that the assigned texture is filled with proper data since I read it back with glGetTexImage and checked it. Do I need to call other functions to bind and activited the texture? I have almost the same code for 2d textures which is working.
When I change the shader code this way:
#version 420
uniform sampler1D colorRamp;
in float height;
out vec4 FragColor;
void main()
{
FragColor = vec4(height, height, height, 1.0); // change!
}
I get this output:
I prepared some demo source code that reproduces the error. The source can be found here.
It generates the following output:
The 1d texture is created this way - with only red pixels:
static GLuint Create1DTexture()
{
GLuint textureId_;
// generate the specified number of texture objects
glGenTextures(1, &textureId_);
assert(glGetError() == GL_NO_ERROR);
// bind texture
glBindTexture(GL_TEXTURE_1D, textureId_);
assert(glGetError() == GL_NO_ERROR);
// tells OpenGL how the data that is going to be uploaded is aligned
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
assert(glGetError() == GL_NO_ERROR);
float data[] =
{
1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f
};
glTexImage1D(
GL_TEXTURE_1D, // Specifies the target texture. Must be GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.
0, // Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
GL_RGBA32F,
3*sizeof(float)*4,
0, // border: This value must be 0.
GL_RGBA,
GL_FLOAT,
data
);
assert(glGetError() == GL_NO_ERROR);
// texture sampling/filtering operation.
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT);
assert(glGetError() == GL_NO_ERROR);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_T, GL_REPEAT);
assert(glGetError() == GL_NO_ERROR);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
assert(glGetError() == GL_NO_ERROR);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
assert(glGetError() == GL_NO_ERROR);
glBindTexture(GL_TEXTURE_1D, 0);
assert(glGetError() == GL_NO_ERROR);
return textureId_;
}
Texture binding is done this way:
GLuint samplerLocation = glGetUniformLocation(rc.ToonHandle, "ColorRamp");
glUniform1i(samplerLocation, 0);
glActiveTexture(GL_TEXTURE0 + 0);
glBindTexture(GL_TEXTURE_1D, rc.texure1d);

Answer 1

Found the bug:
glTexImage1D(
GL_TEXTURE_1D, // Specifies the target texture. Must be GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.
0, // Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
GL_RGBA32F,
3/*3*sizeof(float)*4*/, // bug fix!!!!
0, // border: This value must be 0.
GL_RGBA,
GL_FLOAT,
data
);