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GL1: work around lack of NPOT textures in Windows OpenGL renderer. 

OpenGL 1.1 permits implementations to reject non-power-of-2 sized
textures. In practice this only affects the default Windows OpenGL
implementation, i.e. with no vendor drivers installed. This is still
important in case the application runs in a VM.
pull/33/merge
whitequark 2016-10-09 20:24:49 +00:00
parent 7787923d05
commit 819c4c5742
1 changed files with 49 additions and 6 deletions
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51
src/render/rendergl1.cpp
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@ -201,6 +201,31 @@ Canvas::Fill *OpenGl1Renderer::SelectFill(hFill hcf) {
return fill;
}
static int RoundUpToPowerOfTwo(int v)
{
for(int i = 0; i < 31; i++) {
int vt = (1 << i);
if(vt >= v) {
return vt;
}
}
return 0;
}
static bool NeedsGl1V1Workaround()
{
static bool didGlVersionCheck, needsGl1V1Workaround;
if(!didGlVersionCheck) {
didGlVersionCheck = true;
if(!strcmp((const char*) glGetString(GL_VERSION), "1.1.0")) {
// The default Windows GL renderer really does implement GL 1.1,
// and cannot handle non-power-of-2 textures, which is legal.
needsGl1V1Workaround = true;
}
}
return needsGl1V1Workaround;
}
void OpenGl1Renderer::SelectTexture(std::shared_ptr<const Pixmap> pm) {
if(current.texture.lock() == pm) return;
@ -220,8 +245,19 @@ void OpenGl1Renderer::SelectTexture(std::shared_ptr<const Pixmap> pm) {
case Pixmap::Format::BGR:
ssassert(false, "Unexpected pixmap format");
}
if(!NeedsGl1V1Workaround()) {
glTexImage2D(GL_TEXTURE_2D, 0, format, pm->width, pm->height, 0,
format, GL_UNSIGNED_BYTE, &pm->data[0]);
} else {
GLsizei width = RoundUpToPowerOfTwo(pm->width);
GLsizei height = RoundUpToPowerOfTwo(pm->height);
glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0,
format, GL_UNSIGNED_BYTE, 0);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, pm->width, pm->height,
format, GL_UNSIGNED_BYTE, &pm->data[0]);
}
glEnable(GL_TEXTURE_2D);
current.texture = pm;
@ -603,17 +639,24 @@ void OpenGl1Renderer::DrawFaces(const SMesh &m, const std::vector<uint32_t> &fac
void OpenGl1Renderer::DrawPixmap(std::shared_ptr<const Pixmap> pm,
const Vector &o, const Vector &u, const Vector &v,
const Point2d &ta, const Point2d &tb, hFill hcf) {
double xfactor = 1.0,
yfactor = 1.0;
if(NeedsGl1V1Workaround()) {
xfactor = (double)pm->width / RoundUpToPowerOfTwo(pm->width);
yfactor = (double)pm->height / RoundUpToPowerOfTwo(pm->height);
}
UnSelectPrimitive();
SelectFill(hcf);
SelectTexture(pm);
SelectPrimitive(GL_QUADS);
glTexCoord2d(ta.x, ta.y);
glTexCoord2d(ta.x * xfactor, ta.y * yfactor);
ssglVertex3v(o);
glTexCoord2d(ta.x, tb.y);
glTexCoord2d(ta.x * xfactor, tb.y * yfactor);
ssglVertex3v(o.Plus(v));
glTexCoord2d(tb.x, tb.y);
glTexCoord2d(tb.x * xfactor, tb.y * yfactor);
ssglVertex3v(o.Plus(u).Plus(v));
glTexCoord2d(tb.x, ta.y);
glTexCoord2d(tb.x * xfactor, ta.y * yfactor);
ssglVertex3v(o.Plus(u));
}