Do not glReadPixels() with type GL_RED.

GLES can only read RGBA pixels. Downconvert ourselves when we need to.

diff --git a/init.cpp b/init.cpp
index 89998f40d64d81c957dfabc897ba61b6b63a7552..c5e81135dccb1de327883715f735a8e9506be41b 100644 (file)
--- a/init.cpp
+++ b/init.cpp
@@ -122,14 +122,14 @@ void measure_texel_subpixel_precision()
        // Now read the data back and see what the card did.
        // (We only look at the red channel; the others will surely be the same.)
        // We assume a linear ramp; anything else will give sort of odd results here.
-       float out_data[width];
-       glReadPixels(0, 0, width, 1, GL_RED, GL_FLOAT, out_data);
+       float out_data[width * 4];
+       glReadPixels(0, 0, width, 1, GL_RGBA, GL_FLOAT, out_data);
        check_error();
 
        float biggest_jump = 0.0f;
        for (unsigned i = 1; i < width; ++i) {
-               assert(out_data[i] >= out_data[i - 1]);
-               biggest_jump = max(biggest_jump, out_data[i] - out_data[i - 1]);
+               assert(out_data[i * 4] >= out_data[(i - 1) * 4]);
+               biggest_jump = max(biggest_jump, out_data[i * 4] - out_data[(i - 1) * 4]);
        }
 
        assert(biggest_jump > 0.0);
@@ -242,16 +242,16 @@ void measure_roundoff_problems()
 
        // Now read the data back and see what the card did. (Ignore the last value.)
        // (We only look at the red channel; the others will surely be the same.)
-       unsigned char out_data[512];
-       glReadPixels(0, 0, 512, 1, GL_RED, GL_UNSIGNED_BYTE, out_data);
+       unsigned char out_data[512 * 4];
+       glReadPixels(0, 0, 512, 1, GL_RGBA, GL_UNSIGNED_BYTE, out_data);
        check_error();
 
        int wrongly_rounded = 0;
        for (unsigned i = 0; i < 255; ++i) {
-               if (out_data[i * 2 + 0] != i) {
+               if (out_data[(i * 2 + 0) * 4] != i) {
                        ++wrongly_rounded;
                }
-               if (out_data[i * 2 + 1] != i + 1) {
+               if (out_data[(i * 2 + 1) * 4] != i + 1) {
                        ++wrongly_rounded;
                }
        }

diff --git a/test_util.cpp b/test_util.cpp
index f48ff7fffcc8bbd4cf6478b1aec5d12b22ae74f4..a5cd44cf251ed514697c79d567b15f037b620aa7 100644 (file)
--- a/test_util.cpp
+++ b/test_util.cpp
@@ -132,7 +132,20 @@ void EffectChainTester::run(float *out_data, GLenum format, Colorspace color_spa
        chain.render_to_fbo(fbo, width, height);
 
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
-       glReadPixels(0, 0, width, height, format, GL_FLOAT, out_data);
+       check_error();
+       if (!epoxy_is_desktop_gl() && format == GL_RED) {
+               // GLES will only read GL_RGBA.
+               float *temp = new float[width * height * 4];
+               glReadPixels(0, 0, width, height, GL_RGBA, GL_FLOAT, temp);
+               check_error();
+               for (int i = 0; i < width * height; ++i) {
+                       out_data[i] = temp[i * 4];
+               }
+               delete[] temp;
+       } else {
+               glReadPixels(0, 0, width, height, format, GL_FLOAT, out_data);
+               check_error();
+       }
 
        if (format == GL_RGBA) {
                width *= 4;
@@ -150,7 +163,20 @@ void EffectChainTester::run(unsigned char *out_data, GLenum format, Colorspace c
        chain.render_to_fbo(fbo, width, height);
 
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
-       glReadPixels(0, 0, width, height, format, GL_UNSIGNED_BYTE, out_data);
+       check_error();
+       if (!epoxy_is_desktop_gl() && format == GL_RED) {
+               // GLES will only read GL_RGBA.
+               unsigned char *temp = new unsigned char[width * height * 4];
+               glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, temp);
+               check_error();
+               for (int i = 0; i < width * height; ++i) {
+                       out_data[i] = temp[i * 4];
+               }
+               delete[] temp;
+       } else {
+               glReadPixels(0, 0, width, height, format, GL_UNSIGNED_BYTE, out_data);
+               check_error();
+       }
 
        if (format == GL_RGBA) {
                width *= 4;