OpenGL - Unable to write to frame buffer (or read it properly) - opengl

So I've been trying to get shadow mapping to work, but I was unsuccessful, and I am now trying to simply write anything to the frame buffer and then render it to a quad as a texture. I've been looking at this small piece of code for 10 hours, so I thought it might finally be time to ask for some help. Do let me know if you need any more information or if something is unclear.
I started by following this tutorial. After completing it two times, and straight copy pasting a third time I gave up, and started to look elsewhere for information. My current code is a bit of a mess, but I have tried to extract what is crucial
Here is how I set up my FBO with a TEXTURE2D (_shadowMap and _shadowMapFBO are private variables in the class acting as the main program):
glGenTextures(1, &_shadowMap);
glBindTexture(GL_TEXTURE_2D, _shadowMap);
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_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT32, SHADOW_WIDTH, SHADOW_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
glGenFramebuffers(1, &_shadowMapFBO);
glBindFramebuffer(GL_FRAMEBUFFER, _shadowMapFBO);
glDrawBuffer(GL_NONE);
glReadBuffer(GL_NONE);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, _shadowMap, 0);
GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
{
std::cout << "Frame buffer failed" << std::endl;
system("pause");
exit(1);
}
glBindFramebuffer(GL_FRAMEBUFFER, 0);
I then do the first render pass in the main loop:
glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
glBindFramebuffer(GL_FRAMEBUFFER, _shadowMapFBO);
glClear(GL_DEPTH_BUFFER_BIT);
_shadowShader.bind();
glBindVertexArray(_cubeVAO);
glDrawElements(GL_TRIANGLES, _numberOfIndicesCube, GL_UNSIGNED_SHORT, 0);
glBindVertexArray(_planeVAO);
glDrawElements(GL_TRIANGLES, _numberOfIndicesPlane, GL_UNSIGNED_SHORT, 0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glDrawBuffer(GL_BACK);
glReadBuffer(GL_BACK);
Initially I wanted to create a shadow map, but at this point I'm simply trying to write an explicit value to the entire texture attached to the frame buffer using the following shader pair (the one used by _shadowShader)
Vertex
#version 450
in layout(location=0) vec3 position;
uniform mat4 mvp;
void main()
{
gl_Position = mvp * vec4(position, 1.0f);
}
Fragment
#version 450
out float depth;
void main()
{
depth = 0.0f;
}
I then finish up by trying to display the texture on a quad:
glViewport(0, 0, _screenWidth, _screenHeight);
glClearColor(0.7f, 0.5f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
_testShader.bind();
glBindTexture(GL_TEXTURE_2D, _shadowMap);
glBindVertexArray(_quadVAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, 0);
Here is the fragment shader for the quad:
#version 450
in vec2 textureCoordinates;
uniform sampler2D _shadowMap;
out vec4 color;
void main()
{
float depth = texture2D(_shadowMap, textureCoordinates).r;
color = texture2D(_shadowMap, textureCoordinates);
}
But to my continuous frustration, the quad appears white although I output 0.0f (black) from the fragment shader...I know the quad is able to display a texture, as I've been able to render a normal texture displaying a .jpg onto it. So, this is where I'm at now; any ideas, pointers, thoughts, motivational words etc?
EDIT I: So after some more time I have at least figured out that the texture is loaded correctly and that I'm able to read from it. I did this by actually loading a image onto it during initialization and then not writing to it. The quad then displays the texture correctly. So there must be something wrong with how I'm writing to it.
EDIT II: So I got it working; I sat down with a TA and copy pasted the code (yeah, I know...doesn't get much better than that) and it now works. Thanks Bart :)

Your shadow pass fragment shader is just wrong:
#version 450
out float depth;
void main()
{
depth = 0.0f;
}
This does just declare a single channel color output, which will be written to the color attachment (which you don't have). Since you want to write to the depth attachment of your FBO, you have to use the builtin gl_FragDepth output variable. If you don't do it, the GL will write the lineariliy interpolated window space depth value to the depth buffer.
Note that typically, you clear the depth buffer to 1.0, and when using a typical perspective projection, your objects would appear very close to 1.0, say at 0.99something, as the depth value, so it is very likely that converting the result to just 8 bit grayscale will look all white.

Related

No alpha blending working for me in OpenGL 4.6

I am working on a particle system using OpenGL and version 460 shaders that are compiled to SPIR-V.
My particles are based on PNG textures with alpha and it's actually pretty straight forward, I have done it on earlier OpenGL versions before.
However, the particle in the output window remains to be a square, the corners are black - meaning, the alpha channel is drawn as black. I used different PNG files, one with the particle as grey on alpha or grey on black. I set in the fragment shader the forth component to 0.0 or 0.5 to see any change, but nothing changed. I tried to change the formats in the loadTexture function, but still the same.
I tried all different kinds of blending modes and changed the order of the lines. I noticed in RenderDoc, that the target blend is disabled. But no change of glEnable(GL_BLEND) to another position was helpful.
I would really appreciate your help!
// init stuff
glEnable(GL_POINT_SPRITE);
initbasicShaders(); // vertex, fragment
initTexture();
...
void application::initTexture()
{
m_ParticleTex = Texture(); // empty constructor
m_ParticleTex.loadTexture(TEXTURE_PATH);
GLint baseImageLoc = glGetUniformLocation(m_RenderProgramHandle, "u_Texture");
glUseProgram(m_RenderProgramHandle);
glUniform1i(baseImageLoc, 0);
glActiveTexture(GL_TEXTURE0 + 0);
glBindTexture(GL_TEXTURE_2D, m_ParticleTex.getTextureID());
}
// using the library stb_image
void Texture::loadTexture(const char* fileName)
{
int channels, width, height;
unsigned char * localBuffer;
m_FilePath = fileName;
localBuffer = stbi_load(fileName, &width, &height, &channels, 4);
glGenTextures(1, &m_TextureID);
glBindTexture(GL_TEXTURE_2D, m_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_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, localBuffer);
glBindTexture(GL_TEXTURE_2D, 0);
if (localBuffer) {
stbi_image_free(localBuffer);
}
}
...
...
...
// Now - the render loop:
void application::runOpenGLBuffer()
{
Log::logInfoRun(m_Name, "OpenGL buffer");
glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
glEnable(GL_POINT_SMOOTH);
glDisable(GL_DEPTH_TEST);
glEnable(GL_ALPHA_TEST);
glPointSize(PARTICLE_SIZE);
glHint(GL_POINT_SMOOTH_HINT, GL_NICEST);
glUseProgram(m_RenderProgramHandle);
this->updateTextures();
glDrawArrays(GL_POINTS, 0, NUM_PARTICLES);
}
...
// and the fragment shader
#version 460
#extension GL_ARB_separate_shader_objects : enable
layout(std430, binding = 3) buffer density_block
{
float density[];
};
void main()
{
// densitColor is just a variable color from density
vec4 particleColor = vec4(texture(u_Texture, gl_PointCoord) * densityColor);
color = particleColor;
}
And here the output in the render frame and information from RenderDoc:
The parameter to glEnable (like GL_BLEND or GL_POINT_SMOOTH) is a enumerator constant rather than a bits of a bit field. Different enumerator constants can't be concatenated by the | operator. Each state has to be enabled separately:
glEnable(GL_BLEND | GL_POINT_SMOOTH);
glEnable(GL_BLEND);
glEnable(GL_POINT_SMOOTH);
Note, the bitwise or operation calculates a new value by performing "or" to each bit of both values. The result may have not any meaning to glEnable. This causes that neither GL_BLEND nor GL_POINT_SMOOTH is enabled in your code.

Making position buffer for deferred rendering - noise in the generated textures

I'm trying to implement deferred shading for the first time but I'm having trouble generating the buffers. I've started trying to make just the position buffer so here is the relative code:
glGenFramebuffers(1, &gBuffer);
glBindFramebuffer(GL_FRAMEBUFFER, gBuffer);
glGenTextures(1, &gPosition);
glBindTexture(GL_TEXTURE_2D, gPosition);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, 1024, 1024, 0, GL_RGB, GL_FLOAT,
NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, gPosition, 0);
unsigned int rbo;
glGenRenderbuffers(1, &rbo);
glBindRenderbuffer(GL_RENDERBUFFER, rbo);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 1024, 1024);
glBindRenderbuffer(GL_RENDERBUFFER, 0);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo);
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
std::cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!" << std::endl;
glBindFramebuffer(GL_FRAMEBUFFER, 0);
The framebuffer is successfully completed and we go to the main loop:
glBindFramebuffer(GL_FRAMEBUFFER, gBuffer);
glActiveTexture(gPosition);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glViewport(0, 0, 1024, 1024);
mat4 modelMatrix = mat4(1);
glUseProgram(gShader);
glUniformMatrix4fv(mgLoc, 1, GL_FALSE, &modelMatrix[0][0]);
glUniformMatrix4fv(pgLoc, 1, GL_FALSE, &projectionMatrix[0][0]);
glUniformMatrix4fv(vgLoc, 1, GL_FALSE, &viewMatrix[0][0]);
glBindVertexArray(objVAO);
glDrawArrays(GL_TRIANGLES, 0, objVertices.size());
glBindFramebuffer(GL_FRAMEBUFFER, 0);
And this is the fragment shader:
layout (location=0) out vec3 gPosition;
in vec3 vertex_world;
out vec4 FragColor;
void main()
{
FragColor=vec4(vertex_world,1.0);
}
The position buffer seems fine :
However, if you look at my shader I haven't given a value to gPosition. It seems like the buffer is just taking the output fragColor.
This is what I plan to do but it gives me wrong results:
layout (location=0) out vec3 gPosition;
in vec3 vertex_world;
void main()
{
gPosition=vertex_world;
}`
It does pass something to the position buffer but you will see that it's quite strange:
What could be wrong?
Edit/Solved
It turns out that I had to define gPosition as a vec4 in the fragment shader. It works perfectly now. So the new question is why did it work now?
glActiveTexture does not take a texture name, but selects the active texture unit (GL_TEXTURE0 + n) – yeah, the name is misleading.
Anyway, it seems like you want to bind the position buffer texture before rendering to it. Why? If you actually did that you might end up with a feedback loop – see https://www.khronos.org/opengl/wiki/Framebuffer_Object#Feedback_Loops. You're fine as long as you don't sample from it, but the mere possibility of having a feedback loop might throw you into a slower codepath. So try do not do that. You've bound the texture as an attachment to the FBO, that's enough.
As far as rendering an actual position buffer is concerned: Why do that in the first place? Just use a depth buffer texture (instead of renderbuffer) and reconstruct the position from the single depth value and un-projection.

Issue with using Sampler2D with a Shader

! I am aware that there are easier ways to draw to the screen than this, but i need to do it this specific way !
I am drawing to a texture through a fbo.
I am then using a shader to re-draw it onto the screen, doing so with a sampler2D (of the texture) and having the shader set gl_fragColor to the color of the sampler2D at the specific point the fragment shader is at.
The issue i am having is that the display buffer (which the shader is drawing the fbo to) is only a solid blue, even though i draw a white squares to the fbo with a blue background.
My Code:
Main Render Loop:
while(!Display.isCloseRequested()){
//Drawing on the fbo a blue background and white square
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fboID);
glColor3f(0,0,1);
drawQuad(0,0,WIDTH,HEIGHT);
glColor3f(1,1,1);
drawQuad(0,0,50,50);
//Trying to draw the texture from the previous fbo
//on to the display buffer with a fragment shader,
//however it only draws a blue background, no white square.
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
GL13.glActiveTexture(GL13.GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D,texID);
glUseProgram(shaderProgram);
glUniform1i(glGetUniformLocation(shaderProgram, "tex"), 0);
glUniform1f(glGetUniformLocation(shaderProgram, "width"), WIDTH);
glUniform1f(glGetUniformLocation(shaderProgram, "height"), HEIGHT);
glBegin(GL_QUADS); {
glVertex2f(0, 0);
glVertex2f(0, HEIGHT);
glVertex2f(WIDTH, HEIGHT);
glVertex2f(WIDTH, 0);
} glEnd();
glUseProgram(0);
Display.update();
}
My Shader:
uniform sampler2D tex;
uniform float width;
uniform float height;
void main() {
vec4 color = texture2D( tex, gl_FragCoord.xy / vec2(width, height));
gl_FragColor = color;
}
Init method for the fbo:
texID=glGenTextures();
fboID=glGenFramebuffersEXT();
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fboID);
glBindTexture(GL_TEXTURE_2D, texID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, WIDTH, HEIGHT, 0,GL_RGBA, GL_INT, (java.nio.ByteBuffer) null);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT,GL_COLOR_ATTACHMENT0_EXT,GL_TEXTURE_2D, texID, 0);
glBindTexture(GL_TEXTURE_2D, 0);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
I think one reason why this is happening could be becuase i am not correctly passing the Sampler2D to the shader but i not sure how to fix it.
If any could tell why this is happening or how to fix it (or even just a point in the right direction) it would be much appreciated!
(Sorry for any bad English!)
You have transposed your calls to glUniform1i (...) and glUseProgram (...).
At the time that glUniform1i(glGetUniformLocation(shaderProgram, "tex"), 0); is executed, the currently active program is 0 and that should in fact be generating the following error:
GL_INVALID_OPERATION is generated if there is no current program object.
If you swap the two lines mentioned above, that should fix your problem. In the future you should make a point of checking glGetError (...) when something does not work.
UPDATE: Now that the original problem is fixed, you are not setting the texture minification filter correctly.
To set enumerants, you must use glTexParameteri (...). glTexParameterf (...) is going to interpret the value passed as a floating-point number and GL_LINEAR (0x2601) has type GLenum (32-bit unsigned integer). Fortunately all core OpenGL enums only use the lower 16-bits so they can be expressed precisely as 32-bit floats (can express all integers up to 224), but you can see why you would not want to convert an integer constant to a float.
Therefore, the following line:
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
Needs to be:
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
UPDATE 2: You must use normalized texture coordinates when using texture2D (...).
gl_FragCoord.xy has the range [0, width] and [0, height], which is outside the normalized range for any framebuffer larger than 1x1. To fix that, you must divide by width and height.
texelFetch (...) allows you to use unnormalized coordinates, but it requires GLSL 1.30 and you would have to cast gl_FragCoord.xy to ivec2 to use it. It may also prove inconvenient if you ever draw into an FBO that has different dimensions than your window.

OpenGL 3.0: Cannot use framebuffer object in shader (black)

I want to draw a scene to a framebuffer object and later use the texture of that in another shader. For testing purposes I would just like to actually output the framebuffer object's textur. However, the corresponding part (a rectangle) is just completely black. So I'm wondering whether either the rendering to the fbo does not work or the access to that.
Here are the important code parts:
Called before rendering to the FBO:
void TextureRenderer::bind() {
glBindFramebuffer(GL_FRAMEBUFFER, mFramebufferName);
// glPushAttrib(GL_VIEWPORT_BIT);
glViewport(0, 0, mWidth, mHeight);
}
This is the plane on which the FBO should be displayed. The first texture "mTextureId" is another texture I've loaded from a TGA file and displaying that works just fine. However, the second "mReflectionTextureId" is the one from the VBO and this is the one which I cannot access (or it really is black because there was an error before).
void WaterPlane::render(const Transform& trans) {
mat4 projection = trans.projection;
mat4 view = trans.view;
mat4 model = mat4::identitiy();
glPushAttrib(GL_ALL_ATTRIB_BITS);
glPushClientAttrib(GL_CLIENT_ALL_ATTRIB_BITS);
mShader->bind();
// lets activate the textures now
glEnable(GL_TEXTURE_2D);
// bumpmap texture
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, mTextureId);
// set the texture
mShader->seti("waterBumpTextureSampler", 0);
// rendered reflection texture (has been rendered previously with the help of Framebuffer object for reflection)
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, mReflectionTextureId);
// set reflection texture
mShader->seti("renderedReflection", 1);
mShader->setMatrix("matProjection", projection, GL_TRUE);
mShader->setMatrix("matView", view, GL_TRUE);
mShader->setMatrix("matModel", model, GL_TRUE);
mShader->setf("vecTextureShift", mTextureShift);
mVboWaterPlane->render();
mShader->release();
glDisable(GL_TEXTURE_2D);
glPopClientAttrib();
glPopAttrib();
}
Finally, the water.fs shader:
#version 130
in vec4 VertPosition;
in vec4 VertNormal;
in vec4 VertColor;
in vec4 VertTexture;
uniform vec3 lightPos;
uniform sampler2D waterBumpTextureSampler;
uniform sampler2D renderedReflection; // reflection on the water
void main()
{
// completely black
gl_FragColor = texture( renderedReflection, VertTexture.xz);
// if this is actually commented in the bumpmap texture will be shown nicely
// gl_FragColor = texture( waterBumpTextureSampler, VertTexture.xz);
}
So in general displaying textures work, however displaying the texture from the framebuffer object does not (or the rendering to it previously to that did not work).
Screenshot:
EDIT:
The initialization code of the FBO:
void TextureRenderer::init() {
glGenFramebuffers(1, &mFramebufferName);
glBindFramebuffer(GL_FRAMEBUFFER, mFramebufferName);
// The texture we're going to render to
glGenTextures(1, &mRenderedTextureId);
// "Bind" the newly created texture : all future texture functions will modify this texture
glBindTexture(GL_TEXTURE_2D, mRenderedTextureId);
cout << "TextureRenderer: creating with id " << mFramebufferName << " and tex id " << mRenderedTextureId << endl;
// Give an empty image to OpenGL ( the last "0" )
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, mWidth, mHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);
// Poor filtering. Needed !
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
// The depth buffer
// TODO this is probably not needed?!?!?!
glGenRenderbuffers(1, &mDepthRenderBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, mDepthRenderBuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, mWidth, mHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, mDepthRenderBuffer);
// Set "renderedTexture" as our colour attachement #0
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mRenderedTextureId, 0);
// Set the list of draw buffers.
GLenum DrawBuffers[1] = {GL_COLOR_ATTACHMENT0};
glDrawBuffers(1, DrawBuffers); // "1" is the size of DrawBuffers
// Always check that our framebuffer is ok
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
cout << "Problem during creation of TextureRenderer" << endl;
throw std::runtime_error("Something Bad happened here");
}
unbind();
cout << "TextureRenderer: creating with id " << mFramebufferName << "...done" << endl;
}
The bind code (which is immediately called before rendering to the FBO):
void TextureRenderer::bind() {
glBindFramebuffer(GL_FRAMEBUFFER, mFramebufferName);
// glPushAttrib(GL_VIEWPORT_BIT); // http://wiki.delphigl.com/index.php/Tutorial_Framebufferobject
glViewport(0, 0, mWidth, mHeight);
}
This is now solved. The problem simply was, that I was using wrong texture coordinates in the water.fs (fragment) shader. Below the corrected variant of water.fs. Note the difference in calculation of the coordinates that are given then to the texture(...) function.
in vec4 VertPosition;
in vec4 VertNormal;
in vec4 VertColor;
in vec4 VertTexture;
in vec4 VertTexturePS;
uniform vec3 lightPos;
uniform sampler2D waterBumpTextureSampler;
uniform sampler2D texReflection; // reflection on the water
void main()
{
vec2 originalTexCoord = VertTexturePS.xy / VertTexturePS.w * 0.5 + vec2(0.5);
gl_FragColor = texture( texReflection, originalTexCoord.xy);
}
VertTexturePS is just calculated in the water.vs by this:
VertTexturePS = matProjection * matView * matModel * vec4(Position.xyz, 1);

OpenGL & GLSL: Greyscale texture not showing

I'm trying to show a greyscale texture on the screen. I create my texture via
glGenTextures(1, &heightMap);
glBindTexture(GL_TEXTURE_2D, heightMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_R32F, 512, 512, 0, GL_RED, GL_FLOAT, colorData);
colorData is a float[512*512] with values between 0.0 and 1.0.
When rendering, I use:
glBindTexture(GL_TEXTURE_2D, heightMap);
glUniform1i(shader.GetUniformLocation("textureSampler"), 0);
shader.GetUniformLocation is a function of a library we use at university. It is essentially the same as glGetUniformLocation(shader, "textureSampler"), so don't be confused by it.
I render two triangles via triangle strip. My fragment shader is:
#version 330
layout(location = 0) out vec4 frag_color;
in vec2 texCoords;
uniform sampler2D textureSampler;
void main()
{
frag_color = vec4(texture(textureSampler, texCoords).r, 0, 0, 1);
}
I know the triangles are rendered correctly (e.g. if I use vec4(1.0, 0, 0, 1) for frag_color, I get a completely red screen). However with the line above, I only get a completely black screen. Every texture value seems to be 0.0.
Does anyone have an idea, what I have done wrong? Are there mistakes in that few lines of code or are these completely correct and the error is somewhere else?
As one of the comments below says, setting glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); and glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); solves the problem. :)