OpenGL ES 3 Instance render fails, but works on desktop

Issue

I am able to use instance rendering on desktop with GLSL 330 core but I cannot run the same C++ code on Android (using SDL2 and the NDK build system and Android Studio).

The logcat error is shown below:

-18 15:49:57.264 20996-21026/package I/SDL/APP: shaders/mobile/sceneShader.frag.glsl compiled successfully
10-18 15:49:57.274 20996-21026/package I/SDL/APP: Program link failed: --From Vertex Shader:
10-18 15:49:57.274 20996-21026/packageI/SDL/APP: linker error: multiple attribute attempt to bind at same location 
10-18 15:49:57.274 20996-21026/packageI/SDL/APP: --From Fragment Shader:
10-18 15:49:57.274 20996-21026/package I/SDL/APP: linker error: multiple attribute attempt to bind at same location 

My desktop and mobile shader codes are identical except for the #version line at the top of the file (specifying es or desktop versions respectively).

My mobile shader code is shown here:

#version 300 es

precision mediump float;

// attribute data
layout (location = 0) in vec3 VertexPosition;
layout (location = 1) in vec2 VertexTexCoord;
layout (location = 2) in vec3 VertexNormal;
layout (location = 3) in mat4 InstanceTransform; // used for translating the positions of instance renders

// varying data
layout (location = 0) out vec3 vPosition;
layout (location = 1) out vec2 vTexCoord0;
layout (location = 2) out vec2 vTexCoord1;
layout (location = 3) out vec3 vTexSkyboxCoord;
layout (location = 4) out vec3 vNormal;
layout (location = 5) out vec3 vClampColor;

// uniform data
layout (location = 0) uniform bool uInstanceRendering;

layout (location = 1) uniform mat4 uModelViewMatrix;
layout (location = 2) uniform mat4 uProjectionMatrix;
layout (location = 3) uniform mat3 uNormalMatrix;

layout (location = 4) uniform vec2 uTexOffset0;
layout (location = 5) uniform vec2 uTexOffset1;

void main(void)
{
    vec4 mvPosition;

    if (uInstanceRendering)
    {
        mvPosition = uModelViewMatrix * InstanceTransform * vec4(VertexPosition, 1.0);
    }
    else
    {
        mvPosition = uModelViewMatrix * vec4(VertexPosition, 1.0);
    }

    vTexSkyboxCoord = VertexPosition; // for skybox rendering

    const float atlasRows = 6.0f;
    vTexCoord0 = (VertexTexCoord / atlasRows) + uTexOffset0;
    vTexCoord1 = (VertexTexCoord / atlasRows) + uTexOffset1;

    vPosition = mvPosition.xyz;

    vNormal = normalize(uNormalMatrix * VertexNormal);

    vClampColor = clamp(VertexPosition, 0.0, 1.0);

    gl_Position = uProjectionMatrix * mvPosition;

#ifdef GL_ES
    gl_PointSize = 10.0f;
#endif
}

After tediously using comments on both the C++ side and GLSL side I have pin-pointed the error to this line of code:

mvPosition = uModelViewMatrix * InstanceTransform * vec4(VertexPosition, 1.0);

If I comment it out the program will compile but it will not be able to perform a glDraw*Instaced call without tons of gpu related errors (shown below from logcat).

10-18 15:58:42.504 29196-29238/package W/Adreno-GSL: <gsl_ldd_control:408>: ioctl fd 49 code 0xc02c093d (IOCTL_KGSL_SUBMIT_COMMANDS) failed: errno 35 Resource deadlock would occur
10-18 15:58:42.504 29196-29238/package W/Adreno-GSL: <log_gpu_snapshot:323>: panel.gpuSnapshotPath is not set.not generating user snapshot
10-18 15:58:42.504 29196-29238/packageW/Adreno-GSL: <gsl_ldd_control:408>: ioctl fd 49 code 0xc02c093d (IOCTL_KGSL_SUBMIT_COMMANDS) failed: errno 35 Resource deadlock would occur
10-18 15:58:42.504 29196-29238/packageW/Adreno-GSL: <log_gpu_snapshot:323>: panel.gpuSnapshotPath is not set.not generating user snapshot
10-18 15:58:42.504 29196-29238/packageW/Adreno-GSL: <gsl_ldd_control:408>: ioctl fd 49 code 0xc02c093d (IOCTL_KGSL_SUBMIT_COMMANDS) failed: errno 35 Resource deadlock would occur
10-18 15:58:42.504 29196-29238/packageW/Adreno-GSL: <log_gpu_snapshot:323>: panel.gpuSnapshotPath is not set.not generating user snapshot
10-18 15:58:42.504 29196-29238/packageW/Adreno-GSL: <gsl_ldd_control:408>: ioctl fd 49 code 0xc02c093d (IOCTL_KGSL_SUBMIT_COMMANDS) failed: errno 35 Resource deadlock would occur
10-18 15:58:42.504 29196-29238/packageW/Adreno-GSL: <log_gpu_snapshot:323>: panel.gpuSnapshotPath is not set.not generating user snapshot
10-18 15:58:42.504 29196-29238/packageW/Adreno-GSL: <gsl_ldd_control:408>: ioctl fd 49 code 0xc02c093d (IOCTL_KGSL_SUBMIT_COMMANDS) failed: errno 35 Resource deadlock would occur
10-18 15:58:42.504 29196-29238/packageW/Adreno-GSL: <log_gpu_snapshot:323>: panel.gpuSnapshotPath is not set.not generating user snapshot
10-18 15:58:42.504 29196-29238/packageW/Adreno-ES20: <finish_current_fbo_rendering:315>: GL_OUT_OF_MEMORY

I made a minimal example to simply test instance rendering and the same issue pops up with OpenGL ES 3 (also using SDL still).

#version 300 es
precision mediump float;

// attribute data
layout (location = 0) in vec3 aVertexPosition;
layout (location = 1) in vec2 aVertexTexCoord;
layout (location = 2) in vec3 aVertexNormal;
layout (location = 3) in mat4 aInstanceTransform;

// varying data
out vec3 vPosition;
out vec2 vTexCoord;
out vec3 vNormal;

// uniform data
uniform mat4 uModelViewMatrix;
uniform mat4 uProjectionMatrix;
uniform mat3 uNormalMatrix;

void main(void)
{
    vec4 mvTransform = uModelViewMatrix * aInstanceTransform * vec4(aVertexPosition, 1.0);

    vTexCoord = aVertexTexCoord;

    vPosition = mvTransform.xyz;

    vNormal = normalize(uNormalMatrix * aVertexNormal);

    gl_Position = uProjectionMatrix * mvTransform;
}

Here is where I set the vertex data:

glBindBuffer(GL_ARRAY_BUFFER, mVBO_InstanceData);
glBufferData(GL_ARRAY_BUFFER, instanceData.size() * sizeof(glm::mat4), instanceData.data(), GL_STATIC_DRAW);

glEnableVertexAttribArray(3);
glVertexAttribPointer(3, 4, GL_FLOAT, GL_FALSE, sizeof(glm::mat4), reinterpret_cast<GLvoid*>(0));
glVertexAttribDivisor(3, 1); // increment instance data by 1 each iteration

glEnableVertexAttribArray(4);
glVertexAttribPointer(4, 4, GL_FLOAT, GL_FALSE, sizeof(glm::mat4), reinterpret_cast<GLvoid*>(sizeof(glm::vec4)));
glVertexAttribDivisor(4, 1);

glEnableVertexAttribArray(5);
glVertexAttribPointer(5, 4, GL_FLOAT, GL_FALSE, sizeof(glm::mat4), reinterpret_cast<GLvoid*>(2 * sizeof(glm::vec4)));
glVertexAttribDivisor(5, 1);

glEnableVertexAttribArray(6);
glVertexAttribPointer(6, 4, GL_FLOAT, GL_FALSE, sizeof(glm::mat4), reinterpret_cast<GLvoid*>(3 * sizeof(glm::vec4)));
glVertexAttribDivisor(6, 1);

Solution

I figured out that just using 'glBindAttribLocation' instead of layout qualifiers in the vertex shader fixes the issue. I even used the same numbering scheme as the one I had with the layout qualifiers. I wonder if I could've just set the instance data with 4 vec4's? I guess the mat4 throws off the numbering scheme on my mobile device?

Answered By - BlazePascal